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1. ------IND- 2012 0320 D-- EN- ------ 20120611 --- --- PROJET

DEUTSCHER AUSSCHUSS FÜR STAHLBETON (GERMAN COMMITTEE FOR REINFORCED CONCRETE)

DafStb Guideline On the reinforcement of concrete parts with adhesive bonding

Part 1: Design and construction

Draft March 2012

The requirements of Directive 98/34/EC of the European Parliament and of the Council of 22 June 1998 laying down a procedure for the provision of information in the field of technical standards and regulations and of rules on Information Society services (OJ L 204 of 21 July 1998, p. 37), recently amended by Directive 2006/96/EC (OJ L 363 of 20 December 2006, p. 81) have been taken into account.

Regarding the standards, other documents and technical specifications related to products or test procedures named in this Guideline, the rule is that other products and test procedures may be applied if they meet the standards and other provisions and/or technical specifications of other EU Member States, Turkey or other EFTA State, that is a Contract State of the European Economic Area (EEA), provided the specified level of protection with regard to safety, health and suitability of use is equally permanently achieved.

Published by:Deutscher Ausschuss für Stahlbeton e. V. – DAfStb.Budapester Straße 31D – 10787 Berlin-TiergartenPhone: 030 [email protected]

The Deutsche Ausschuss für Stahlbeton (DAfStb) retains all rights, including translation into foreign languages. This document or any part thereof may not be photocopied or otherwise reproduced without the explicit permission of DAfStb.

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DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding - Part 1: Design and construction

Foreword

(RV 1) This Guideline regulates the planning, design and execution of the reinforcement of reinforced concrete and prestressed concrete components with fibre composite materials which are bonded on or into indent cuts and bonded steel tabs.

(RV 2) The reinforcements to be bonded to the component surface to enhance shear strength include commercial carbon fibre plates, carbon fibre sheeting and flat steel sections. Commercial carbon fibre plates with special geometric requirements can also be glued into indent cuts in the component.

(RV 3) The structure of this Guideline is based on DIN EN 1992-1-1. Unless stated otherwise, the respective sections of DIN EN 1992-1-1 and its National Annex shall apply.

(RV 4) Requirements and information on product and system approvals are contained in Part 2 of this Guideline.

(RV 5) Part 3 of this Guideline includes information on execution.

(RV 6) Part 4 of this Guideline contains supplemental rules on the Repair Guideline with regard to planning of reinforcement measures.

(RV 7) The prefix RV in this Guideline indicates additional chapters, sections, paragraphs, figures, tables and equations to DIN EN 1992-1-1 and the National Annex.


Contents List Part 11General ...................................................................................................................9

1.1Scope...............................................................................................................................91.1.1 Scope of Eurocode 2..............................................................................................................91.1.2 Scope of Part 1-1 of Eurocode 2............................................................................................9RV 1.1.3 Scope of DAfStb Guideline Reinforcement of concrete parts with adhesive bonding......9

1.2 Normative references....................................................................................................91.2.1 General reference standards..................................................................................................91.2.2 Other reference standards......................................................................................................9

1.3 Assumptions................................................................................................................101.4 Distinctions between principles and application rules............................................101.5Definitions.....................................................................................................................10

1.5.1General.................................................................................................................................. 101.5.2 Additional terms and definitions used in this Standard.........................................................10

1.6 Symbols........................................................................................................................11

2 Basis of design......................................................................................................172.1 Requirements...............................................................................................................17

2.1.1 Basic requirements...............................................................................................................172.1.2 Reliability management........................................................................................................172.1.3 Design working life, durability and quality management.......................................................17

2.2 Principles of limit state design...................................................................................172.3 Basic variables.............................................................................................................17

2.3.1 Actions and environment influences.....................................................................................172.3.2 Material and product properties............................................................................................172.3.3 Deformations of concrete.....................................................................................................182.3.4 Geometric data..................................................................................................................... 18

2.4 Verification by the partial factor method...................................................................182.4.1 General................................................................................................................................. 182.4.2 Design values....................................................................................................................... 182.4.3 Combinations of actions.......................................................................................................192.4.4 Verification of static equilibrium............................................................................................19

2.5 Design assisted by testing.........................................................................................192.6 Supplementary requirements for foundations.........................................................192.7 Requirements of fixings..............................................................................................19NA.2.8 Documentation......................................................................................................19

NA.2.8.1 Scope............................................................................................................................. 19NA.2.8.2 Drawings........................................................................................................................ 19NA.2.8.3 Design analysis..............................................................................................................19NA.2.8.4 Specification of works.....................................................................................................19

3 Materials.................................................................................................................193.1 Concrete.......................................................................................................................19

3.1.1 General................................................................................................................................. 193.1.2 Strength................................................................................................................................ 203.1.3 Deformation characteristics..................................................................................................203.1.4 Creep and shrinkage............................................................................................................203.1.5 Stress-strain curve for non-linear methods of analysis and for strain calculations...............203.1.6 Design compressive and tensile strengths...........................................................................203.1.7 Stress-strain curve for section design...................................................................................20

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3.1.8 Flexural tensile strength.......................................................................................................203.1.9 Confined concrete................................................................................................................20

3.2 Reinforcing steel..........................................................................................................203.2.1General.................................................................................................................................. 203.2.2 Properties............................................................................................................................. 203.2.3 Strength................................................................................................................................ 203.2.5 Welding................................................................................................................................ 213.2.6 Fatigue................................................................................................................................. 213.2.7 Stress-strain curve for section design...................................................................................21

3.3 Prestressing steel........................................................................................................213.3.1General.................................................................................................................................. 213.3.2 Properties............................................................................................................................. 213.3.3 Strength................................................................................................................................ 213.3.4 Ductility characteristics.........................................................................................................213.3.5 Fatigue................................................................................................................................. 213.3.6 Stress-strain curve for section design...................................................................................213.3.7 Prestressing tendons in sheaths..........................................................................................21

3.4 Prestressing devices...................................................................................................223.4.1 Anchorages and couplers.....................................................................................................223.4.2 External non-bonded tendons..............................................................................................223.4.2.1 General.............................................................................................................................. 223.4.2.2 Anchorages....................................................................................................................... 22

RV 3.5 Materials for reinforcement using adhesive bonding........................................22RV 3.6 Component to be reinforced................................................................................22RV 3.7 Bonded CFRP plates.............................................................................................23RV 3.8 CFRP plates bonded in indent cuts.....................................................................23RV 3.9 Steel tabs................................................................................................................23RV 3.10 Bonded CF sheeting............................................................................................23

RV 3.10.1 Bending reinforcement.................................................................................................23RV 3.10.2 Shear reinforcement.....................................................................................................23RV 3.10.3 Column reinforcement..................................................................................................23

4. Durability and cover to reinforcement.................................................................244.1 General.........................................................................................................................244.2 Environmental conditions...........................................................................................244.3 Requirements for durability........................................................................................244.4 Analysis........................................................................................................................24

5. Structural analysis................................................................................................245.1 General.........................................................................................................................24

5.1.1 General requirements...........................................................................................................245.1.2 Special requirements for foundations...................................................................................255.1.3 Load cases and combinations..............................................................................................255.1.4 Second order effects............................................................................................................25

5.2 Geometric imperfections............................................................................................255.3 Idealizations and simplifications...............................................................................25

5.3.1 Structural models for overall analysis...................................................................................255.3.2 Geometric data..................................................................................................................... 25

5.4 Linear-elastic analysis................................................................................................255.5 Linear elastic analysis with limited redistribution...................................................25

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5.6 Plastic analysis............................................................................................................265.6.1 General................................................................................................................................. 265.6.2 Plastic analysis for beams, frames and slabs.......................................................................265.6.3 Rotation capacity.................................................................................................................. 265.6.4 Design with strut and tie models...........................................................................................26

5.7 Non-linear analysis......................................................................................................265.8 Analysis of second order effects with axial load.....................................................26

5.8.1 Definitions............................................................................................................................. 265.8.2 General................................................................................................................................. 265.8.3 Simplified criteria for second order effects............................................................................265.8.4 Creep.................................................................................................................................... 265.8.5 Methods of analysis..............................................................................................................265.8.6 General method.................................................................................................................... 265.8.7 Method based on nominal stiffness......................................................................................275.8.8 Method based on nominal curvature....................................................................................275.8.9 Compression members with biaxial eccentricity...................................................................27

5.9 Lateral shift of slender beams....................................................................................275.10 Prestressed members and structures.....................................................................27

5.10.1General................................................................................................................................ 275.10.2 Prestressing force during tensioning..................................................................................275.10.3 Prestress force................................................................................................................... 275.10.4 Immediate losses of prestress for pre-tensioning...............................................................285.10.5 Immediate losses of prestress for post-tensioning.............................................................285.10.6 Time dependent losses of prestress for pre- and post-tensioning......................................285.10.7 Consideration of prestress in analysis................................................................................285.10.8 Ultimate limit state..............................................................................................................285.10.9 Effects of prestressing at serviceability limit state and limit state of fatigue........................28

5.11 Analysis for some particular structural members..................................................28RV 5.12 Verification of shear tension at plate end.........................................................28

6 Ultimate limit states (ULS).....................................................................................296.1 Bending with or without axial force...........................................................................29

RV 6.1.1 Reinforcement using bonded CFRP plates and CF sheeting for components subjected primarily to bending stress.............................................................................................29

RV 6.1.2 Reinforcement with bonded steel tabs for components predominantly subject to bending stress............................................................................................................................. 43

RV 6.1.3 Bending reinforcement using CFRP plates bonded in indent cuts..................................47RV 6.1.4 Column reinforcement using confinement......................................................................51

6.2 Shear force...................................................................................................................566.2.1 Analysis................................................................................................................................ 566.2.2 Members not requiring design shear reinforcement.............................................................566.2.3 Members requiring design shear reinforcement...................................................................566.2.4 Shear between web and flange............................................................................................576.2.5 Shear transfer in joints..........................................................................................................57RV 6.2.6 Shear reinforcement.......................................................................................................58RV 6.2.7 End links to prevent breakage due to shift......................................................................61

6.3 Torsion..........................................................................................................................616.4 Punching shear............................................................................................................61

6.4.1 General................................................................................................................................. 616.4.2 Loaded areas and critical sections used in analyses............................................................616.4.3 Analysis................................................................................................................................ 616.4.4 Punching shear resistance of slabs and column bases without shear reinforcement...........616.4.5 Punching shear resistance of slabs and column bases with shear reinforcement................61

6.5 Design with strut and tie models...............................................................................61

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6.5.1 General................................................................................................................................. 616.5.2 Struts.................................................................................................................................... 626.5.3 Ties...................................................................................................................................... 626.5.4 Design of nodes................................................................................................................... 62

6.6 Anchorages and laps..................................................................................................626.7 Partial area loading......................................................................................................626.8 Fatigue analysis...........................................................................................................62

6.8.1 General................................................................................................................................. 626.8.2 Internal forces and stresses for fatigue verification..............................................................626.8.3 Combination of actions.........................................................................................................626.8.4 Verification procedure for reinforcing and prestressing steel................................................626.8.5 Verification using damage equivalent stress range..............................................................626.8.6 Other verifications................................................................................................................626.8.7 Verification of concrete under compression or shear...........................................................63RV 6.8.8 CFRP plates bonded to a surface..................................................................................63RV 6.8.9 Bonded steel tabs...........................................................................................................65RV 6.8.10 CFRP plates bonded in indent cuts..............................................................................65

7 Serviceability limit states (SLS).............................................................................667.1 General.........................................................................................................................667.2 Limitation of stresses..................................................................................................667.3 Crack control................................................................................................................67

7.3.1 General................................................................................................................................. 677.3.2 Minimum reinforcement for limitation of crack width.............................................................677.3.3 Control of cracking without detailed analysis........................................................................677.3.4 Calculation of crack width.....................................................................................................67RV 7.3.5 Crack width-limiting effect of bonded plates...................................................................67

7.4 Limitation of deformations.........................................................................................707.4.1 General................................................................................................................................. 707.4.2 Cases where calculations may be omitted...........................................................................707.4.3 Checking deflections by calculation......................................................................................70

8 Detailing of reinforcement and prestressing tendons — general........................708.1 General.........................................................................................................................708.2 Spacing of reinforcing steel bars...............................................................................70

RV 8.2.1 Spacing of plates............................................................................................................70

8.3 Bending of steel...........................................................................................................72RV 8.3.1 Bending of the bonded reinforcement.............................................................................72

8.4 Anchorage of longitudinal reinforcement.................................................................728.4.1 General................................................................................................................................. 728.4.2 Ultimate bond stress.............................................................................................................728.4.3 Basic anchorage length........................................................................................................728.4.4 Design anchorage length......................................................................................................73RV 8.4.5 Anchorage of the bonded reinforcement........................................................................73RV 8.4.6 Base dimension of the adhesive bond for reinforcement bonded to a surface...............73RV 8.4.7 Base dimension of the adhesive bond in indent cuts......................................................73

8.5 Anchorage of links and shear reinforcement...........................................................748.6 Anchorage by welded bars.........................................................................................748.7 Laps and mechanical couplers..................................................................................74

8.7.1 General................................................................................................................................. 748.7.2 Laps..................................................................................................................................... 748.7.3 Lap length............................................................................................................................. 74

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8.7.4 Transverse reinforcement in the lap zone............................................................................748.7.5 Laps for welded mesh fabrics made with ribbed wires.........................................................74RV 8.7.6 Plate lap joints................................................................................................................75

8.8 Additional rules for large diameter bars...................................................................758.9 Bundled bars................................................................................................................75

8.9.1 General................................................................................................................................. 758.9.2 Anchorage of bundles of bars...............................................................................................758.9.3 Lapping bundles of bars.......................................................................................................75

8.10 Prestressing tendons................................................................................................768.10.1 Arrangement of prestressing tendons and ducts................................................................768.10.2 Anchorage of pre-tensioned tendons..................................................................................768.10.3 Anchorage zones of post-tensioned or unbonded members..............................................768.10.4 Anchorages and couplers for prestressing tendons...........................................................768.10.5 Deviators............................................................................................................................ 76

9 Detailing arrangements for structural members...................................................769.1 General.........................................................................................................................769.2 Beams...........................................................................................................................76

9.2.1 Longitudinal reinforcement...................................................................................................769.2.2 Shear reinforcement.............................................................................................................779.2.3 Torsion reinforcement...........................................................................................................779.2.4 Surface reinforcement..........................................................................................................779.2.5 Indirect supports................................................................................................................... 77RV 9.2.6 Links of the bonded reinforcement.................................................................................77RV 9.2.7 Execution of bonded links...............................................................................................78

9.3 Solid slabs....................................................................................................................809.3.1 Flexural reinforcement..........................................................................................................809.3.2 Shear reinforcement.............................................................................................................80

9.4 Flat slabs......................................................................................................................809.4.1 Slab at internal columns.......................................................................................................809.4.2 Slab at edge columns...........................................................................................................809.4.3 Punching shear reinforcement..............................................................................................80

9.5 Columns.......................................................................................................................819.5.1 General................................................................................................................................. 819.5.2 Longitudinal reinforcement...................................................................................................819.5.3 Shear reinforcement.............................................................................................................81RV 9.5.4 Column reinforcement....................................................................................................81

9.6 Walls.............................................................................................................................819.6.1 General................................................................................................................................. 819.6.2 Vertical reinforcement...........................................................................................................819.6.3 Horizontal reinforcement......................................................................................................829.6.4 Shear reinforcement.............................................................................................................82

9.7 Deep beams..................................................................................................................829.8 Foundations.................................................................................................................82

9.8.1 Pile caps............................................................................................................................... 829.8.2 Column and wall footings.....................................................................................................829.8.3 Tie beams............................................................................................................................. 829.8.4 Column footing on rock.........................................................................................................829.8.5 Bored piles........................................................................................................................... 82

9.9 Regions with discontinuity in geometry or action (D regions)...............................829.10 Limitation of damage due to accidental actions....................................................82

9.10.1 General............................................................................................................................... 829.10.2 Proportioning of ties............................................................................................................82

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9.10.3 Continuity and anchorage of ties........................................................................................83

10 Additional rules for precast concrete elements and structures.........................8311 Lightweight aggregate concrete structures........................................................8312 Plain and lightly reinforced concrete structures................................................83Annex RV K: Recommended system coefficients (informative).............................84

RV K1 Values for reinforcements created by adhesive bonding:.................................84RV K2 System coefficient for columns:..........................................................................84

Annex RV L Determination of cross-section values (informative)..........................85RV L1 Ultimate limit state.................................................................................................85

RV L1.1 General............................................................................................................................ 85RV L1.2 Rectangular cross-sections.............................................................................................85RV L1.3 T-beams.......................................................................................................................... 85

RV L2 In the ultimate limit state.......................................................................................86RV L3 Approximation method for the ultimate limit state.............................................87

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1General

1.1Scope

1.1.1 Scope of Eurocode 2No additions or amendments

1.1.2 Scope of Part 1-1 of Eurocode 2No additions or amendments

RV 1.1.3 Scope of DAfStb Guideline Reinforcement of concrete parts with adhesive bonding(RV1) This part of the Guideline contains basic rules for the design, calculation and design of reinforcement measures with adhesive bonding for plain, reinforced and prestressed concrete structures.

(RV 2) This part of the Guideline does not apply to:

The reinforcement of lightweight aggregate concrete structures; The reinforcement of lightweight aggregate concrete structures using prestressed fibre

composite materials.(RV3) The requirements for products and systems for reinforcement of concrete components in accordance with general building inspectorate approvals shall apply (see also Part 2 of this Guideline).

(RV4) Bonded reinforcement may be used for components subject to predominantly static and non-static actions, in accordance with DIN EN 1990, Sections 1.5.3.11, 1.5.3.12 and Section 4.1.

(RV5) Application of this part of the Guideline requires component strength of at least C12/15 determined in accordance with DIN EN 13791.

1.2 Normative references

1.2.1 General reference standardsNo additions or amendments

1.2.2 Other reference standardsIn addition to the documents cited in DIN EN 1992-1-1 with DIN EN 1992-1-1/NA, the following documents are necessary for use of this document.

DIN EN 1504-2, Products and systems for the protection and repair of concrete structures - Definitions, requirements, quality control and evaluation of conformity - Part 2: Surface protection systems for concrete DIN EN 1993-1-1, Eurocode 3: Design of steel structures - Part 1-1: General rules and rules for buildings DIN EN 1993-1-9, Eurocode 3: Design of steel structures - Part 1-9: FatigueDIN EN 1993-1-8, Eurocode 3: Design of steel structures - Part 1-8: Design of joints DIN 18195, Waterproofing of buildingsDIN V 18026, Surface protection systems for concrete products according to DIN EN 1504-2:2005-01DAfStb Guideline “Protection and repair of concrete components” DBV-Merkblatt “Bauen im Bestand/Beton und Betonstahl” [DBV Code on building with existing parts/concrete and reinforcing steel]

1.3 Assumptions(RV2) The assumptions according to DIN EN 1990 and DIN EN 1992-1-1 shall also apply in this Guideline. This Guideline contains additional and deviating rules with regard to DIN EN 1992-1-1 on reinforcement of concrete parts with adhesive bonding.

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1.4 Distinctions between principles and application rulesNo additions or amendments

1.5Definitions

1.5.1GeneralNo additions or amendments

1.5.2 Additional terms and definitions used in this StandardRV 1.5.2.27 AdhesiveNon-metallic material that can join materials through surface adhesion for the joint to possess sufficient internal strength (cohesion).

RV 1.5.2.28 SheetingSpecial textile surface structure used for reinforcement in fibre composite materials. Sheeting consists of parallel fibre bundles.

RV 1.5.2.29 Bonded reinforcement Materials with tensile strength bonded to the concrete using an adhesive to make the bond shear-resistant.

RV 1.5.2.30 Plates bonded into indent cuts Here the plates are bonded by adhesive into indents that were cut into the concrete.

RV 1.5.2.31 PlateUnidirectional fibre composite materials premade at the factory and thermally hardened.

RV 1.5.2.32 Bonded linksSteel tabs or fibre composite material bonded to the component surface to enhance shear strength, enveloping the component in curtailed or non-curtailed form. RV 1.5.2.33 Breakage due to shiftSpecial type of breakage occurring at the plate end of bonded reinforcements, where a shift in tensile force may pull off the concrete cover and the entire bonded reinforcement.

RV 1.5.2. 34 Large-area defective spotFor individual areas of L ≥ 500 mm in the direction of the longitudinal axis of the reinforcement or, for levelling layers on a steel tab, bonded CFRP plate, sheeting or CFRP plates bonded in indent cuts with a total length L ≥ 20 % of individual plate length.

RV 1.5.2.35 Small-area defective spotA defective spot that is not a large-area defective spot.

RV 1.5.2.36 CFRP / CFCarbon fibre reinforced plastic (CFRP) is a fibre-plastic composite material in which carbon fibres are embedded in a plastic matrix for reinforcement. Carbon fibres (CF) are fibres that are industrially manufactured from carbon materials.

RV 1.5.2.37 Non-curtailed link Bonded link where only the tension zone is closed. In this link, tensile forces are lead through the composite into the compression zone.

1.6 SymbolsIn addition to the documents cited in DIN EN 1992-1-1 with DIN EN 1992-1-1/NA, the following symbols are necessary for use of this document

Latin upper case symbols

Ac,eff (sectional) area of zone of concrete section in which reinforcement is effectiveAi ideal sectional area

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AL sectional area of bonded reinforcementALw sectional area of shear reinforcement D cross-sectional diameter of the compression member Dc diameter of the core cross-section confined by reinforcing steel EIS,g total link rigidity Ejl confinement rigidity of the fibre composite material ELk characteristic modulus of elasticity of the bonded reinforcement ELm mean modulus of elasticity of the bonded reinforcementELW modulus of elasticity of the shear reinforcement FbLRd design composite material strength of the bonded reinforcement FbLRd,max design maximum composite material strength of the bonded reinforcement at the anchoring

pointFbsm mean bond strength of the reinforcement FCEd concrete compressive force FD

Lk,BL plate force at Point D at the crack edge subject to the lesser loadFLEd design concentrated force of the bonded reinforcement FLRd maximum tensile force of the bonded reinforcement FLuk characteristic plate breakage force Fs tensile force of reinforcing steel Fsd design tensile force of reinforcing steel Fsyd design tensile force of reinforcing steel at yield pointFu(b) self-induced contact pressure Fu,2 self-induced contact pressure for b = 0.4Fu,4 self-induced contact pressure for b = 0.8Füd,max tension force that can be transmitted at the lap joint of the bonded reinforcement FD

Lk,BL resistance of plate force difference in Point DFG

Lk,BL resistance of plate force difference in Point G FL,1 increase in bond strength due to curtailment of linkFLE,equ plate force difference under quasi-constant loadFLEd design place force changeFLEd

O plate force difference under top load FLEd

U plate force difference under bottom load FLk,BF bond strength resistance at the intermediate crack element due to frictionFLk,BL base bond strength at the intermediate crack element FLk,KF bond strength resistance at the intermediate crack element due to curvatureFLR,fat1 resistance to plate force difference that will not cause fatigue failure FLR,fat2 resistance stress amplitude of the plate force at the crack edge subject to the higher loadFLRd design resistance to change in plate forceIi theoretical sectional moment of inertia of the reinforced concrete support K factor to increase curvature due to creep Mcr cracking moment of the reinforced concrete cross-sectionMEqp first order bending moment due to quasi-permanent combination of actions taking into

account imperfections MRd design resistance moment NEqp axial force due to quasi-permanent combination of actions Tf temperature defining the glass transition zone Vccd contact component of concrete parts with shear reinforcement Vct shear resistance for components without shear reinforcement

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Vc,LE shear force at which breakage due to shift without curtailment of link does not yet occur VEd design concentrated shear forceVL shear resistance of the shear reinforcement VRd design resistance to effective shear VRd,c design shear resistance of components without shear reinforcement VRd,c,LE design resistance against breakage due to shift VRd,L design shear reinforcement component VRd,s design shear reinforcement component in parts with shear reinforcement VRd.cc design loadbearing capacity component of the concrete in parts with shear reinforcement Vs shear resistance of internal shear reinforcement Wc,0 resistance moment of the concrete cross-section in the uncracked state

Latin lower case symbols

a1 magnitude of shift of tension envelope aL distance between axes of bonded reinforcement aL distance of the bonded reinforcement from the support axis ar distance of the bonded reinforcement from the free component edge for CFRP plates

bonded in indent cutsas axis distance of reinforcement embedded in concretebc width of concrete component to be reinforced beff,i effective flange width bL width of the bonded reinforcement bL,eff effective plate width when using several plates for analysis of increase in bond strength due

to curtailment of linkbLw width of the shear reinforcement bs width of cut for CFRP plates bonded in indent cutsc concrete cover da effective static depth of the reinforcing steel reinforcement at the support da

L effective static depth of the bonded reinforcement at the support dL effective static depth of the reinforcement e0 planned first order biaxial eccentricity ei additional accidental biaxial eccentricity according to DIN EN 1992-1-1etot first order biaxial eccentricity fb bond strengthfbd design bond strengthfbk characteristic bond strengthfbLd design bond strength of the reinforcement fbLk characteristic bond strength of the reinforcement‚

fbLk,max characteristic maximum bond strength of the reinforcement at the end anchorage fbLwd design strength of shear reinforcement due to bond effect fbsm mean bond stress of the reinforcing steel reinforcementfcck characteristic compressive strength of confined concrete fck(tV0) characteristic unconfined concrete compressive strength at the time of reinforcement (to be

determined by measurements on the component) fck* characteristic value of a simple stress-strain curve for designfcm(tV0) mean unconfined concrete compressive strength at the time of load application (to be

determined by measurements on the component) fct,eff mean effective axial tensile strength of concrete

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fctk characteristic axial tensile strength of concretefctm mean axial tensile strength of concrete fctm,surf calculated mean axial tensile surface strength of concretefctm,surf,is mean axial tensile surface strength of concrete determined in-situ in accordance with DIN

EN 1542 fcti,surf,is individual axial tensile surface strength of concrete determined in-situ in accordance with

DIN EN 1542 fcufrpk characteristic resistance to concrete compressive stress resulting from the confinement

effect of fibre composite material in the event of its failure fGck compressive strength of the adhesive fGtk tensile strength of the adhesivefGud,Lw design strength of the lap jointfGuk,Lw characteristic strength of the lap joint fGuk,Lw,max maximum characteristic strength of the lap joint fLud design tensile strength of the plate fLuk characteristic material strength of the bonded reinforcement fLw strength of the shear reinforcement fLwd design strength of the shear reinforcement fLwd,G design strength of the shear reinforcement due to material strength of overlaps or curves fLwd,GF design strength of the shear reinforcement due to material strength in fibre composite

reinforcements fLwd,GS design strength of the shear reinforcement due to material strength in steel tabsfLyd design yield strength of steel tabs fywk characteristic yield strength of the reinforcing steel confinement by links or hoopinghc,ef height of zone of concrete section in which reinforcement is effectivehLw height of the shear reinforcement kL bond factor for CFRP plates bonded in indent cutskL,eff bond factor for CFRP plates bonded in indent cuts taking into account time effectsks bond factor for reinforcement embedded in concrete ks,eff bond factor for embedded reinforcements taking into account time effectskt bond creep factorlbL bond length of the bonded reinforcement lbL,lim bond length related to anchorage analysis lbL,max effective bond length lbs bond length of the reinforcing steel le,0 dispersion length of the reinforcing steel ls,A leg length of the curtailment angle ls,U leg length of the curtailment linklu,Lw lap length of the linklu,Lw,max effective lap length of the link lü,max effective lap length of the bonded reinforcement nsi number of reinforcing steels p reduction in shear compression due to deviating zones of influence of the confining

reinforcements rc curve radius s spacing of links along the longitudinal axis of the component or helix height sa

Lr slip of bonded reinforcement at the bending crack closest to the point of zero moment scr,max maximum crack spacing under working loadsL0k maximum slip according to bilinear bond approach

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sLr slip of the bonded reinforcement sLw axis distance of shear reinforcement sr spacing of bending cracks tG adhesive thicknesstL theoretical thickness of the bonded reinforcement tLW theoretical thickness of the shear reinforcement ts depth of cut for CFRP plates bonded in indent cutstw,eff thickness of loaded reinforcing steel confinement t residual life span in days xa compression zone height at the support za

L inner lever arm of the plate at the support za

s inner lever arm of the reinforcing steel at the support zj

s distance (+/-) of reinforcing steel longitudinal bar j from centre of gravity of the gross concrete cross-section

zL inner lever arm of the bonded reinforcement zm mean inner lever arm zs inner lever arm of the reinforcing steel

Greek lower case symbols

reduction factor for resistance stress amplitude1 completeness coefficient of the tension block 3 factor describing the influence of higher concrete strengths on moistureb ratio between bonded reinforcement width and web width E reduction factor for fatigue analysis F reduction factor taking into account the influence of moisture k increase factor taking into account creep distribution spread L bond factor for CFRP plates bonded in indent cutsN bond factor for anchorage analysis r reduction factor taking into account the deviation of CF sheeting s bond factor for reinforcement embedded in concretes ratio of the moduli of elasticity of the reinforcing steel longitudinal reinforcement and the non-

confined concrete T reduction factor to take into account the influence of temperature fluctuations on the

loadbearing capacity of the confinement Z reduction factor taking into account the creep behaviour Zeit continuous creep reduction factor for CF sheeting (shear reinforcement) factor taking into account the properties of the compression member (fcm) factor taking into account the effects of concrete compressive strength on the creep base

number 0,k factor taking into account the load level c(t) factor describing the creep development over time when loads are applied to the reinforced

component H factor describing the influence of moisture a

LRk strain of the reinforcement for anchorage analysis a

LRk,lim strain of the reinforcement for anchorage analysis as a function of maximum bond strength a

sRk strain of the reinforcing steel for anchorage analysis cc(t) creep deformation in longitudinal direction of the support during time t cm mean strains of the concrete

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cr1 concrete strain at the crack edge subject to the lesser loadcu ultimate strain of the confined concrete juak ultimate strain of the confined reinforcement at the component taking onto account time-

dependent deformation juk characteristic ultimate strain of the confined reinforcement at the componentL

II strain of the plate in the crack using Bernoulli’s theory on beams assumptionsLuk characteristic ultimate strain of the bonded reinforcement Lm mean strain of the bonded reinforcement Lr1 strain of the bonded reinforcement at the crack edge subject to the lesser loadLRd,max strain of the bonded reinforcement Lud design maximum strain of the bonded reinforcementLW strain of the shear reinforcement L strain of the bonded reinforcement s strain of the reinforcing steel y yield strain in the reinforcing steel yk strain in the reinforcing steel longitudinal reinforcement on reaching the characteristic yield

strainw bar diameter of helical reinforcement BA bond safety factor, bonded onBE bond safety factor, bonded in indent cuts BG safety factor for adhesive bonds of steel on steel or CFRP on CFRP LG safety factor for CF sheetingLL safety factor for CFRP plates L factor taking into account the different elastic stiffnesses and bond strengths ef effective creep Lb adjustment factor for effective bond lengthb1k bond coefficient for bonded reinforcement b2 bond coefficient for bonded reinforcement b3 bond coefficient for bonded reinforcementb4 bond coefficient for bonded reinforcement bsk bond coefficient for reinforcement embedded in concrete fl conversion factor between flexural tensile strength and centric tensile strength of the

concrete h factor for calculating the resistance to plate force change from component curvature at the

intermediate crack element (simplified analysis)K factor for calculating the resistance to plate force change from component curvature at the

intermediate crack element (detailed analysis) l factor taking into account several bonded CFRP plates/steel tabs for increase in bond

strength due to curtailment of link

L1 factor for calculating the resistance to plate force change from adhesive bond at the intermediate crack element (simplified analysis)

LF factor for calculating the resistance to plate force change from bond friction at the intermediate crack element (simplified analysis)

R reduction factor due to curve radiussys product-specific system coefficientt factor for determining the steel tab thickness vb factor for calculating the mean bond stress of the reinforcing steel as a function of the bond

conditionsvb1 factor for calculating the mean bond stress of the reinforcing steel as a function of the bond

conditions

15


vb2 factor for calculating the mean bond stress of the reinforcing steel as a function of the bond conditions

factor (plates bonded in indent cuts) referenced compressive stress of concrete reference angle describing the tension block in the cross-section c reference angle describing the stress distribution in the loaded reinforcing steel longitudinal

reinforcement subject to compression t reference angle describing the stress distribution in the loaded reinforcing steel longitudinal

reinforcement subject to tension L reinforcement level of bonded reinforcement Lw reinforcement level of shear reinforcement s1 level of tensile reinforcement of reinforced concrete wy shear reinforcement levelEqp longitudinal compressive stress of concrete under quasi-permanent combination of actions sr stress in the reinforcing steel on cracking b bond stressbck bond stress of concrete with plates bonded in indent cuts bGk bond stress of adhesive of plates bonded in indent cuts bLd design bond stressL1k maximum bond stress of bilinear approach LFk frictional bond stress Lm mean bond stress of the bonded reinforcement sm mean bond stresses of reinforcing steel 1 factor taking into account the reduction in curvature with an increase in compressive force Nu

2 factor taking into account the geometry of the compression member and strain of the confining reinforcement

L ratio of bond strength of the bonded reinforcement to embedded reinforcement

2 Basis of design

2.1 Requirements

2.1.1 Basic requirements(RV 4) Approval of the product combination of adhesive and reinforcement (system) used shall be furnished in the form of a general building inspectorate approval.

(RV 5) Proof of fire resistance of a component reinforced according to this Guideline that is required for the application shall be furnished in accordance with DIN EN 1992-1-2 and the National Annex without including the reinforcement effect of the adhesive bond. If it is protected from thermal and fire exposure by a fire barrier approved by a building inspectorate, this proof shall be furnished according to the rules of general building inspectorate approval.

2.1.2 Reliability managementNo additions or amendments

2.1.3 Design working life, durability and quality managementNo additions or amendments

2.2 Principles of limit state designNo additions or amendments

16


2.3 Basic variables

2.3.1 Actions and environment influences

2.3.1.1 GeneralNo additions or amendments

2.3.1.2 Thermal effects(RV 4) After approval, no forces may be allocated to the bonded reinforcement above temperature Tf.

Note: Fire protection systems approved by a general building inspectorate for bonded reinforcements shall be used for the fire protection of the bonded reinforcement.

2.3.1.3 Differential settlements/movementsNo additions or amendments

2.3.1.4 PrestressNo additions or amendments

2.3.2 Material and product properties

2.3.2.1 General(RV 3) Requirements of the component to be reinforced are listed in Section RV 3.6.

(RV 4) The requirements for the products and systems for reinforcement are included in Part 2 and in Sections RV 3.7 through RV 3.10.

2.3.2.2 Creep and shrinkage(RV 4) To prevent excessive creep, the continuous bond strength and maximum usage temperature, which are dependent on the construction kit, are specified in the general building inspectorate approvals.

(RV 5) Time-dependent deformations of column reinforcement shall be considered in accordance with Section 6.1.4.

2.3.3 Deformations of concreteNo additions or amendments

2.3.4 Geometric data


2.3.4.2 Supplementary requirements for cast in place pilesNo additions or amendments

2.4 Verification by the partial factor method

2.4.1 GeneralNo additions or amendments

2.4.2 Design values

2.4.2.1 Partial factor for shrinkage actionNo additions or amendments

17


2.4.2.2 Partial factor for prestress No additions or amendments

2.4.2.3 Partial factor for fatigue loads No additions or amendments

2.4.2.4 Partial factor for materials (RV 4) In addition to DIN EN 1992-1-1, the partial safety factors in Section 2.1 shall be used for bonded reinforcement. The safety factor in accordance with DIN EN 1993-1-1 and its National Annex shall be used for steel tabs.

Table RV 2.1: Partial safety factors for bonded reinforcement in the ultimate limit state

Column

1 2 3 4 5 6

Line Design situationFor

CFRP plates

For CF sheetin

g

Bond - reinforcem

ent bonded on

Bond - reinforcement bonded in indent

cuts

Bond - bonding of steel on steel or CFRP on CFRP

1 Designation LL LG BA BE BG

2Permanent and temporary

1.2 1.35 1.5 1.3 1.3

3 Extraordinary 1.05 1.1 1.2 1.05 1.05

2.4.2.5 Partial factors for materials for foundations No additions or amendments

2.4.3 Combinations of actionsNo additions or amendments

2.4.4 Verification of static equilibriumNo additions or amendments

2.5 Design assisted by testingNo additions or amendments

2.6 Supplementary requirements for foundationsNo additions or amendments

2.7 Requirements of fixingsNo additions or amendments

NA.2.8 Documentation

NA.2.8.1 Scope No additions or amendments

NA.2.8.2 Drawings(RV 4)P The components, the reinforcement to be bonded and all fastening elements shall be represented clearly on the drawings. All representations shall match the data in the static calculation and contain all dimensions necessary for the execution of the components and testing of the calculations.

18


(RV 5)P The execution plans shall contain in particular:

the required adhesive pull strengths; designations and components of the reinforcement system; number, dimensions and location of the bonded reinforcement; mutual distance; arrangement,

type and position of the mechanical joining devices; for CFRP plates bonded in indent cuts: depth and width of the cuts including tolerances; special measures for quality assurance, as applicable.

NA.2.8.3 Design analysisNo additions or amendments

NA.2.8.4 Specification of worksNo additions or amendments

3 Materials

3.1 Concrete

3.1.1 General(RV 3)P This Guideline shall only apply to components made of normal weight concrete.

3.1.2 Strength(RV 10)P The surface tensile strength of concrete fctm,surf shall be determined in accordance with Part 4 of this Guideline.

(RV 11) As the components to be reinforced are existing components, converting the concrete strength for predimensioning might be necessary in some cases, which can be done in accordance with DBV-Merkblatt “Bauen im Bestand/Beton und Betonstahl” [DBV Code on building with existing parts/concrete and reinforcing steel].

3.1.3 Deformation characteristicsNo additions or amendments

3.1.4 Creep and shrinkageNo additions or amendments

3.1.5 Stress-strain curve for non-linear methods of analysis and for strain calculationsNo additions or amendments

3.1.6 Design compressive and tensile strengthsNo additions or amendments

3.1.7 Stress-strain curve for section designNo additions or amendments

3.1.8 Flexural tensile strengthNo additions or amendments

3.1.9 Confined concreteNo additions or amendments

19


3.2 Reinforcing steel

3.2.1General(RV 6) This Guideline may be applied to components with reinforcing steels and reinforcement elements that do not meet the requirements of DIN EN 10080 or DIN 488.

3.2.2 Properties(RV 7) For reinforcement of existing components according to this Guideline, the existing reinforcing steels need not comply with DIN EN 1992-1-1 Section 3.2.2 (2); (3); (4); (5) and (6).

(RV 8) The properties of existing reinforcing steels according to DIN EN 1992-1-1 Section 3.2.2 (1) should be known.

(RV 9) For reinforcing steels from 1952 on, the yield points may be used as characteristic values. Approximate values for older reinforcing steels and reinforcement elements may be taken from DBV-Merkblatt “Bauen im Bestand/Beton und Betonstahl” [DBV Code on building with existing parts/concrete and reinforcing steel].

(RV 10) If reinforcing steel without ribbing is used, the bonding properties of smooth steel may be assumed.

3.2.3 StrengthNo additions or amendments

3.2.5 WeldingNo additions or amendments

3.2.6 Fatigue(RV 2) Wöhler curves according to DIN EN 1992-1-1 in combination with DIN EN 1992-1-1/NA may be used for ribbed reinforcing steels, unless different Wöhler curves have been specified in a general building inspectorate approval. For reinforced concrete components that are reinforced only with smooth reinforcing steel, Wöhler curves according to DIN EN 1992-1-1 in combination with DIN EN 1992-1-1/NA may also be used. Smooth reinforcing steel reinforcement may not be used for verification of fatigue in light-weight concrete parts.


3.3 Prestressing steel

3.3.1General(RV 12) For older prestressing steels, the danger potential from stress corrosion cracking shall be assessed. The following prestressing steels are more susceptible to stress corrosion cracking:

Heat-treated prestressing steel St 145/160, round or oval cross-section, manufacturer Felten & Guilleaume Carlswerke AG, trade name Neptun, production period to 1965 high danger potential;

heat-treated prestressing steel St 145/160, round or oval cross-section, manufacturer Hütten- und Bergwerke Rheinhausen AG, trade name Sigma, production period to 1965 high danger potential (round or oval), production period to 1978 danger potential (oval only);

heat-treated Hennigsdorf prestressing steel St 140/160, round or oval cross-section, manufacturer VEB Stahl- und Walzwerk Hennigsdorf (formerly GDR); Heat treatment process with oil end treatment or high temperature thermo-mechanical treatment (HTMT steels), production period to 1993 high danger potential.

3.3.2 PropertiesNo additions or amendments

20


3.3.3 StrengthNo additions or amendments

3.3.4 Ductility characteristicsNo additions or amendments

3.3.5 Fatigue(RV 2) Wöhler curves according to DIN EN 1992-1-1 in combination with DIN EN 1992-1-1/NA may be used for prestressing steels embedded in concrete, if the stress amplitude endured 2106 times and determined in free vibration reaches a minimum tensile strength of 185 N/mm² at a top stress of 65 %. Information on fatigue strength of prestressing steels not embedded in concrete and in free vibration can be found in general building inspectorate approvals for prestressing steel.


3.3.7 Prestressing tendons in sheathsNo additions or amendments

3.4 Prestressing devices

3.4.1 Anchorages and couplers


3.4.1.2 Mechanical propertiesNo additions or amendments

3.4.1.2.1 Anchored tendonsNo additions or amendments

3.4.1.2.2 Anchored devices and anchorage zonesNo additions or amendments

3.4.2 External non-bonded tendonsNo additions or amendments


3.4.2.2 AnchoragesNo additions or amendments

RV 3.5 Materials for reinforcement using adhesive bonding (RV 1) The rules in Part 2 of this Guideline shall apply.

(RV 2) The design equations are based on tests and theoretical considerations. Geometric and material application limits were defined in this context. The following equations thus only apply for the range given in Sections 3.6 to 3.9.

(RV 3) If, in a design case, limit values according to Section 3.6 are exceeded or fallen short of, limit values according to Sections 3.6 may be used for the equations if that results in a less favourable value.

21


(RV 4) For construction kits consisting of adhesive and plate, the rules of general building inspectorate approvals shall apply. Sections 3.7 to 3.9 list the material properties on which the design approaches of this Guideline were based. General building inspectorate approvals may contain deviating rules.

RV 3.6 Component to be reinforced(RV 1) For the components to be reinforced, compression strengths of C12/15 to C50/60 based on DIN EN 206-1, Table 7, was assumed.

(RV 2) For a bond in accordance with Annex RV K, a maximum concrete compression strength of 58 N/mm² and a maximum mean surface tensile strength of concrete of 4 N/mm² may be used in the design equations.

(RV 3) The design equations do not apply to component thicknesses of less than 100 mm. For component thickness less than 100 mm, to be on the safe side, 100 mm may be used for design in equations 6.11 and 6.17.

(RV 4) The design equations apply to components that are planned to be straight or level. The design equations may be applied accordingly to convex component surfaces. The bonding surfaces of CFRP plates must not have concave curvature.

RV 3.7 Bonded CFRP plates (RV 1) The CFRP plates shall be in accordance with Part 2.

(RV 2) If the design equations of this Guideline are applied, the CFRP plates may be bonded in no more than two layers, with the maximum thickness of the CFRP plate cross-section without the adhesive not to exceed 3 mm.

(RV 3) The design equations assume an adhesive layer thickness between 1 mm and 5 mm.

RV 3.8 CFRP plates bonded in indent cuts(RV 1) The CFRP plates shall be in accordance with the requirements in Part 2.

(RV 2) If the design equations of this Guideline are applied, the CFRP plates must not be bonded twice in one indent cut. This does not apply for double plates approved by a building inspectorate.

(RV 3) The design equations assume an insert width of bs according to Equation 3.1.

tL+1 mm≤bs≤tL+3 mm (RV 3.1)(RV 4) If this Guideline is applied, the plate width shall be between 10 mm and 30 mm.

RV 3.9 Steel tabs (RV 1) The design equations apply to steel tabs made of steels according to DIN EN 10025-2, which are 5 mm to 15 mm in thickness.

(RV 2) The strength values for steel tabs to be used in the design equations shall be equivalent to S 235, even if a higher-strength steel is used.

(RV 3) Additionally, the following requirements regarding tab thickness tL as a function of the strength class of the concrete foundation shall be met:

Concrete strength classes C12/15 and C16/20: 5 mm tL 10 mmConcrete strength class C20/25 und C50/60: 5 mm tL 15 mmThe width of the steel tabs bL shall fulfil condition 10 x tL bL 200 mm.

RV 3.10 Bonded CF sheeting

RV 3.10.1 Bending reinforcement (RV 1) In principle, the design equations for bending reinforcement of bonded CFRP plates can be applied to CF sheeting if the reinforcement meets the following conditions. To apply the design equations, the bond factors in accordance with Section 8.4.6 shall be determined or specified by means of approvals for the system used.

22


(RV 2) The elastic stiffness ELmAL per metre is limited to 20 kN/mm to 400 kN/mm.

(RV 3) CF sheeting may be bonded in a maximum of five layers.

(RV 4) The total fibre cross-section per 1 000 mm sheeting width in the total of all layers shall be between 100 mm²/m and 1 800 mm²/m.

RV 3.10.2 Shear reinforcement(RV 1) The bond factors according to Section 8.4.6 shall be determined or specified by means of approvals for the system used.

(RV 2) CF sheeting may be bonded in a maximum of five layers.

RV 3.10.3 Column reinforcement(RV 1) CF sheeting may be bonded in a maximum of ten layers.

4. Durability and cover to reinforcement

4.1 General(RV 7) The permissible ambient conditions, such as exposure classes and other environmental influences (such as temperature) as well as the resulting measures are regulated in the general building inspectorate approvals of the reinforcement kit.

4.2 Environmental conditions(RV 4) Without additional protective measures, the bonded reinforcements may only be used in exposure classes X0, XC1 (dry) or XC3 in accordance with DIN EN 1992-1-1, Table 4.1. In addition, components must not be exposed to direct UV radiation (direct sun radiation or indirect sun from snow or water reflection) or alternating or permanent penetration of moisture in the area of the reinforcements.

(RV 5) If the component is exposed to conditions deviating from that, protective measures in accordance with DAfStb Guideline “Schutz und Instandsetzung von Betonbauteilen” [“Protection and repair of concrete components”] using constructions products in accordance with DIN EN 1504-2 in combination with DIN V 18026 or DIN 18195 or other suitable protective layers shall be provided, which will ensure that the bonded reinforcement of the component is not subjected to alternating or permanent moisture or chemical or mechanical attacks that could damage the bond.

4.3 Requirements for durabilityNo additions or amendments

4.4 AnalysisNo additions or amendments

4.4.1.1GeneralNo additions or amendments

4.4.1.2 Minimum cover cmin

(RV 14) The endurance of the components should not be impaired by CFRP plates bonded in indent cuts, even if the cuts pass into the minimum cover.

4.4.1.3 Allowance in design for deviation No additions or amendments

23


5. Structural analysis

5.1 General

5.1.1 General requirements(RV 15) Structural analysis in accordance with DIN EN 1992-1-1, Sections 5.5 and 5.6 for bending stress is only permitted if no reduction in structural variables compared with linear elastic calculation results in the area to be reinforced.

(RV 16) According to plan, only tensile forces may be allotted to the bonded reinforcement.

(RV 17) In the bending strain zone, the bonded steel tabs, CFRP plates and CF sheeting may be subjected to compressive strain of Lc,max in accordance with Equation (RV 5.1). The strain shall be determined on the assumptions of the stress-strain relations in accordance with DIN EN 1992-1-1, Section 3.1.7.

ε Lc,max=2 000 mm/m⋅√ 1EL⋅tL

≤3 .5 mm/m(RV 5.2)

Where:tL thickness of steel tabs, CFRP plates or CF sheeting in mmEL modulus of elasticity of steel tabs, CFRP plates or CF sheeting in mm

(RV 18) In the bending strain zone, the bonded CFRP plates may be subjected to compressive strain of up to 3.5 mm/m in the compression zone.

(RV 19) The mean prestrain in the serviceability limit states in accordance with DIN EN 1992-1-1, Section 7 from the effects of reinforcement shall be taken into consideration.

5.1.2 Special requirements for foundationsNo additions or amendments

5.1.3 Load cases and combinationsNo additions or amendments

5.1.4 Second order effectsNo additions or amendments

5.2 Geometric imperfectionsNo additions or amendments

5.3 Idealizations and simplifications

5.3.1 Structural models for overall analysisNo additions or amendments

5.3.2 Geometric dataNo additions or amendments

5.3.2.1 Effective width of flanges (all limit states) No additions or amendments

5.3.2.2 Effective span of beams and slabs in buildings No additions or amendments

24


5.4 Linear-elastic analysisNo additions or amendments

5.5 Linear elastic analysis with limited redistribution(RV 7) Structural analysis in accordance with DIN EN 1992-1-1, Section 5.5 for bending stress is only permitted if no reduction in structure compared with linear elastic calculation results in the area to be reinforced.

5.6 Plastic analysis

5.6.1 General(RV 6) Structural analysis in accordance with DIN EN 1992-1-1, Section 5.6 for bending stress is only permitted if no reduction in structural variables compared with linear elastic calculation results in the area to be reinforced.

5.6.2 Plastic analysis for beams, frames and slabsNo additions or amendments

5.6.3 Rotation capacityNo additions or amendments

5.6.4 Design with strut and tie modelsNo additions or amendments

5.7 Non-linear analysis(RV 16) Structural analysis in accordance with DIN EN 1992-1-1, Section 5.7 is not permitted for reinforcement using adhesive bonding.

5.8 Analysis of second order effects with axial load

5.8.1 DefinitionsNo additions or amendments

5.8.2 General(RV 5) Second order effects have been taken into account in the reinforcement of supports whose top and bottom do not shift by determining the reference angle in Section RV 6.1.4.2, if they are subjected to a constant moment.

5.8.3 Simplified criteria for second order effectsNo additions or amendments

5.8.3.1 Slenderness criterion for isolated compression membersNo additions or amendments

5.8.3.2 Slenderness and effective length of isolated membersNo additions or amendments

5.8.3.3 Global second order effects in buildingsNo additions or amendments

5.8.4 CreepNo additions or amendments

25


5.8.5 Methods of analysisNo additions or amendments

5.8.6 General methodNo additions or amendments

5.8.7 Method based on nominal stiffnessNo additions or amendments


5.8.7.2 Nominal stiffnessNo additions or amendments

5.8.7.3 Moment magnification factorNo additions or amendments

5.8.8 Method based on nominal curvatureNo additions or amendments

5.8.8.1GeneralNo additions or amendments

5.8.8.2 Bending moments No additions or amendments

5.8.8.3 Curvature No additions or amendments

5.8.9 Compression members with biaxial eccentricityNo additions or amendments

5.9 Lateral shift of slender beamsNo additions or amendments

5.10 Prestressed members and structures

5.10.1GeneralNo additions or amendments

5.10.2 Prestressing force during tensioningNo additions or amendments

5.10.2.1 Maximum stressing forceNo additions or amendments

5.10.2.2 Limitation of compressive stress in concrete No additions or amendments

5.10.2.3 MeasurementsNo additions or amendments

26


5.10.3 Prestress forceNo additions or amendments

5.10.4 Immediate losses of prestress for pre-tensioningNo additions or amendments

5.10.5 Immediate losses of prestress for post-tensioningNo additions or amendments

5.10.5.1 Losses due to the instantaneous deformation of concrete No additions or amendments

5.10.5.2 Losses due to frictionNo additions or amendments

5.10.5.3 Losses at anchorageNo additions or amendments

5.10.6 Time dependent losses of prestress for pre- and post-tensioningNo additions or amendments

5.10.7 Consideration of prestress in analysisNo additions or amendments

5.10.8 Ultimate limit stateNo additions or amendments

5.10.9 Effects of prestressing at serviceability limit state and limit state of fatigueNo additions or amendments

5.11 Analysis for some particular structural membersNo additions or amendments

RV 5.12 Verification of shear tension at plate end(RV1) The tensile stresses perpendicular to the adhesion surface at the end of the bending reinforcement shall be taken into account, as this may result in so-called breakage due to shift, where the concrete cover at the plate end detaches from the reinforcing steel. Breakage due to shift is shown in 5.1.

Versatzbruch Breakage due to shift

Figure RV 5.1: Schematic presentation of breakage due to shift

27


(RV2) This pull-off force is considered sufficiently anchored when proof in accordance with 6.2.7 is furnished. If this proof is not furnished, outer links in accordance with Section 9.2.6 shall be affixed to the plate end.

6 Ultimate limit states (ULS)

6.1 Bending with or without axial force

RV 6.1.1 Reinforcement using bonded CFRP plates and CF sheeting for components subjected primarily to bending stress

RV 6.1.1.1 Assumptions(RV 1) A simplified analysis (Section Error: Reference source not found) and a more detailed analysis (Section Error: Reference source not found) are available for the analysis of bending reinforcement with bonded CFRP plates and CF sheeting. The simplified analysis is based on ultimate strain that was defined on the safe side. The simplified analysis in accordance with Section Error: Reference source not found is considered accomplished if the listed conditions and ultimate strain have been satisfied. In addition to these methods, there is assessment of localised reinforcement in accordance with Section Error: Reference source not found. The plates may only be subjected to a force that can be anchored to the individual crack and are thus less utilised than in the simplified analysis; however, no anchorage analysis or analysis to avoid breakage due to shift will have to be performed.

(RV 2) In addition to proof of flexural load-bearing capacity in accordance with Section Error: Reference source not found or Error: Reference source not found, an analysis of the shear resistance in accordance with Section Error: Reference source not found and prevention of breakage due to shift Error: Reference source not found shall be furnished. An analysis of prevention of breakage due to shift may be omitted if an end link in accordance with Section Error: Reference source not found was arranged in the construction.

(RV 3) If the bending reinforcement is to be designed for predominantly non-static loads, a fatigue analysis in accordance with Section Error: Reference source not found shall be conducted.

(RV 4) For all analyses except for assessment of localised reinforcement in accordance with Error: Reference source not found, the component shall be at the ultimate limit state of cracking.

NOTE: Here the cracking moment in accordance with Error: Reference source not found or Error: Reference source not found must be exceeded due to the action.

RV 6.1.1.2 Simplified analysis(RV 1) In the area of field moments for non-prestressed components, the analysis of bending reinforcement may be simplified as analysis of flexural load-bearing capacity using the strain of the plate in accordance with Equation Error: Reference source not found. An analysis of the bond strength transmission at the intermediate crack element is not necessary. The anchorage analysis in accordance with Error: Reference source not found shall be performed if one of the following conditions has not been satisfied:

the plate extends to at least 50 mm before the support front edge;

the embedded reinforcing steel is ribbed;

the embedded reinforcing steel is not stepped;

the total plate thickness does not exceed 1.4 mm.

εLd,max=max {0 . 5 mm/m+0 . 1 mm/m⋅l0

h−0 .04 mm/m⋅φs+0 .06 mm/m⋅f cm

{3 .0 mm/m⋅l0

9 700 mm⋅(2− l0

9 700 mm ) for l0≤9 700 mm

3.0 mm/m for l0>9 700 mm(RV 6.3)

Where:

28


fcm mean cylinder compressive strength of the concrete in N/mm²h total component height in mms greatest reinforcing steel diameter in mml0 effective span in mm

(RV 2) If conducting the analysis in (RV 1), the mean cylinder compressive strength of the concrete, which is to be substituted in Equation Error: Reference source not found, shall meet the condition in accordance with Equation Error: Reference source not found.

f ctm,surf≥0 . 26⋅fcm2/3 (RV 6.4)

(RV 3) Within the ultimate strain of the plate, full contribution of the existing reinforcement and the CFRP plates may be assumed in the ultimate limit state. The strain state of the existing reinforcement of reinforced concrete components at the time of reinforcement may be determined on the assumption of the cracked state. An analysis of longitudinal shear between tendon cross-sections shall be conducted in accordance with DIN EN 1992-1-1, Section 6.2.4.

(RV 4) The mean modulus of elasticity values may be used for the CFRP plates or CF sheeting. The design tensile strength of the plates fLud must not be exceeded.

RV 6.1.1.3 Detailed analysis

RV 6.1.1.3.1 Assumptions(RV 1) The more detailed analysis shall assess the following:

Assessment of flexural load-bearing capacity using the strength of the CFRP plates or CF sheeting in accordance with Section Error: Reference source not found. If a simplified analysis of bond strength transmission at the intermediate crack element is conducted in accordance with Section Error: Reference source not found, the strain of 10 mm/m shall be complied with. The design tensile strength of the plates fLud must not be exceeded.

Analysis of bond strength transmission at the intermediate crack element. The crack spacing in accordance with Section Error: Reference source not found or Error: Reference source not found shall be determined first. After that, both a simplified analysis of bond strength transmission at the intermediate crack element in accordance with Section Error: Reference source not found may be performed or a more detailed analysis in accordance with Section Error: Reference source notfound.

Analysis of anchorage of the CFRP plate in accordance with Section Error: Reference source notfound.

(RV 2) For CFRP plates or CF sheeting, the mean modulus of elasticity values may be used for the calculations.

RV 6.1.1.3.2 Analysis of flexural load-bearing capacity (RV 1) Within plate strength fLud, the full contribution of the existing reinforcement and the CFRP plates may be assumed in the ultimate limit state, provided the bond strength analysis was conducted in accordance with Section Error: Reference source not found and Section Error: Reference source not found or Error: Reference source not found. The strain state of the existing reinforcement of reinforced concrete components at the time of reinforcement may be determined on the assumption of the cracked state. An analysis of longitudinal shear between tendon cross-sections shall be conducted in accordance with DIN EN 1992-1-1, Section 6.2.4.

RV 6.1.1.3.3 Determining the crack spacing for reinforced concrete components (RV 1) Using the simplified method, the crack spacing may be determined from 1.5 times the dispersion length of the reinforcing steel in accordance with Equation Error: Reference source not found.

sr=1 . 5⋅le,0 (RV 6.5)(RV 2) The dispersion length may be obtained by Equation Error: Reference source not found. In Equation Error: Reference source not found, zs may be obtained by using 0.85 h (simplified).

29


le,0=M cr

zs⋅Fbsm (RV 6.6)(RV 3) The cracking moment of the cross-section may be obtained by Equation Error: Reference source not found (simplified).

M cr=κ fl⋅f ctm,surf⋅W c,0 (RV 6.7)Where:

fl = (1.6 – h/1 000) 1.0h total component height in mm

(RV 4) When determining the cracking moment for T-beams subject to tensile load, the effective flange width shall be taken into account. The effective flange width for 0.5 beff,i may be obtained in accordance with DIN EN 1992-1-1, Equation (5.7a).

(RV 5) The bond strength per length may be obtained by means of Equation Error: Reference source not found. The mean bond stress of the reinforcing steel may be obtained by means of Equation Error:Reference source not found. Only one bar with spare bar diameter shall be used for double bars. The

spare strut diameter shall be obtained in accordance with φn=√2⋅φ

Fbsm=∑i=1

n

ns,i⋅φi⋅π⋅f bsm(RV 6.8)

(RV 6) The mean bond stress of the reinforcing steel dependant on the reinforcement type may be obtained by means of Equation Error: Reference source not found. The following shall be used for good bond conditions vb1= vb2 =1 and for medium bond conditions vb1= 0.7 and vb2= 0.5.

f bSm={κ vb1⋅0 .43⋅fcm2 /3 for ribbed reinforcing steel

κ vb2⋅0 .28⋅√ f cm for smooth reinforcing steel(RV 6.9)

Where:fcm mean cylinder compressive strength in N/mm²

RV 6.1.1.3.4 Determining the crack distance for prestressed concrete components (RV 1) The crack spacing in prestressed concrete components can be obtained as for reinforced concrete components in accordance with RV 6.1.1.3.3, but for the cracking moment, the prestress force in accordance with Equation Error: Reference source not found shall be taken into account. The prestressing steel reinforcement may be taken into account for bond strength per length in Equation (RV 6.4), if they are in the tension zone where initial cracking occurs. Here the bond strengths of Equation Error: Reference source not found shall be mitigated by the values in Table 6.2 of DIN EN 1992-1-1.

M cr=(κ fl⋅f ctm,surf+σ p⋅A p

Ac)⋅W c,0+σ p⋅A p⋅z p

(RV 6.10)Where:

Ap sectional area of the prestressing steel reinforcement Ac sectional area of the component p prestess of the prestressing steel at the time or reinforcement zp elevation of the prestressing steel relative to the sectional centre of gravity

RV 6.1.1.3.5 Simplified analysis of plate force change at the interim crack element(RV 1) The prestrain of the reinforcement from the reinforcement load shall be taken into account in this analysis.

(RV 2) The strain of the plate must not exceed the maximum strain of LRd,max = 10 mm/m in any point and the design plate strength fLud shall not be exceeded.

30


(RV 3) In addition to arrangements of discrete intermediate crack elements, functions for plate force over the component length may be specified, thereby constricting place force increases (incline).

(RV 4) The intermediate crack elements should start at the maximum moment and be arranged up to the uncracked zone offset at the respective crack spacing. The last intermediate crack element should end in the uncracked zone, which starts after the bending crack which is closest to the point of zero moment.

(RV 5) The plate force change from the action at each intermediate crack element shall be smaller than the resistance plate force change of the bond. ΔF LEd≤ΔFLRd (RV 6.11)(RV 6) The plate force change at the intermediate crack element as a function of crack spacing sr is obtained by means of Equation Error: Reference source not found.ΔF LEd=FLEd( x+sr )−FLEd ( x ) (RV 6.12)(RV 7) The resistance plate force change of the bond per intermediate crack element can be obtained by means of Equation Error: Reference source not found. The resistance plate force change per intermediate crack element is constant for each intermediate crack element in a component to be designed.

ΔF LRd=τ L1 k⋅κL1⋅√sr+ τLFk⋅κLF⋅sr4 /3+

κh

h⋅s

r1/3

γ BA⋅bL

(RV 6.13)Where:

bL plate width in mmL)1 = 2.3LF = 0.1h = 2 000 for flat reinforced concrete components h = 0 for reinforced concrete components sr distance of bending cracks in mm; the value used shall be smaller than 400 mm h component height in mm; the value used shall be greater than 100 mm L1k maximum bond stress in accordance with Annex RV K in N/mm²LFk friction bond stress in accordance with Annex RV K in N/mm²

31


Zustand State Endv. End anchorageLamellenkraftänderung am ZRE Plate force change at the intermediate crack

element

Figure RV 6.2: Schematic of the analyses to be conducted on plate strain and plate force change at the intermediate crack element (RV 8) The plate force FLEd(x) may be obtained by means of Equation Error: Reference source not found in a simplified manner in accordance with Annex RV L 3.

(RV 9) If different crack spacing values for the component to be reinforced are obtained by Equation Error: Reference source not found, the greatest crack spacing may be used for simplified calculation.

RV 6.1.1.3.6 Detailed analysis of plate force change at the interim crack element(RV 1) The prestrain of the reinforcement from the reinforcement load shall be taken into account in this analysis.

(RV 2) The proof shall be furnished for any combination of actions. The superposition principle does not apply.

(RV 3) At each intermediate crack element, which is shown schematically in Error: Reference source not found, proof shall be furnished that the plate force change in accordance with Equation Error: Reference source not found is smaller than the resistance plate force change at the intermediate crack element in accordance with Equation Error: Reference source not found.

ΔF LEd≤ΔFLRd (RV 6.14)(RV 4) The intermediate crack elements should start at the maximum moment and be arranged up to the uncracked zone offset at the respective crack spacing. The last intermediate crack element should end in the uncracked zone, which starts after the bending crack which is closest to the point of zero moment.

32


Zustand StateEndverankerung End anchoringLamellenkraft aus der Einwirkung Place force from actionZwischenrisselement Intermediate crack element

Figure RV 6.3: Schematic presentation of the intermediate crack element (RV 5) The plate force change at the intermediate crack element as a function of crack spacing sr is obtained by means of Equation Error: Reference source not found.

ΔF LEd=FLEd( x+sr )−FLEd ( x ) (RV 6.15)(RV 6) The resistance plate force change of the bond at an intermediate crack element can be obtained by means of Equation Error: Reference source not found and is composed of three parts (see also Error: Reference source not found), one part from the base dimension of the reinforcement bond, one part from the bond friction and one part from the component curvature.

ΔF LRd=ΔF Lk,BL+ ΔFLk,BF+ΔFLk,KF

γ BA (RV 6.16)(RV 7) The part from the base dimension of the reinforcement bond shall be calculated as a function of plate force FLEd at the element’s crack edge subject to the lesser load by means of Equation Error: Reference source not found.

ΔF Lk,BL={ ΔFLk,BLG −

ΔFLk,BLG −ΔFLk,BL

D

FLk,BLD

FLEd für FLEd≤FLk,BLD

√bL2τ L1k sL0k ELmt L+F

LEd2−FLEd für FLk,BLD <FLEd≤FLud

(RV 6.17)Where:

ΔF Lk,BLG =f bLk( sr )⋅bL tL

FLk,BLD =

sL0k ELm bL tL

sr−τ L1k

sr bL

4

ΔF Lk,BLD =√b

L2 τL 1k sL0k ELm tL+FLk,BLD2

−FLk,BLD

33


FLud design plate breakage force (FLud= fLuk/LL · AL) or (FLud= fLuk/LG · AL)FLEd plate force at the intermediate crack element’s crack edge subject to the lesser

load fbLk (sr) characteristic bond strength as a function of crack spacing in accordance with

Equation (RV 8.9)(RV 8) The part from the bond friction is calculated as a function of the plate base force at the intermediate crack element and the crack spacing as well as the frictional bond stress in accordance with Equation Error: Reference source not found.

ΔF Lk,BF={ 0 für FLEd≤FLk,BLD

τLFk⋅bL⋅(sr−2⋅tL⋅ELm

τ L1k⋅(√ τL1k⋅sL0k

t L⋅ELm+

FLEd2

bL2⋅tL2⋅ELm2

−FLEd

bL⋅tL⋅ELm )) für FLk,BLD <FLEd≤FLud

(RV 6.18)(RV 9) The part from the component curvature is obtained by means of Equation Error: Reference source not found based on concrete compression and plate strain values.

ΔF Lk,KF=sr⋅κk⋅εLr 1−εcr 1

h⋅bL (RV 6.19)

Where:k 24.3 · 103 N/mmLr1 plate strain at the crack edge subject to the lesser loadcr1 concrete strain at the crack edge subject to the lesser load

Bilinear: Gleichung Bilinear: equation Bilinear mit Reibung: Gleichung Bilinear with friction: equationKrümmung: Gleichung Curvature: equation

Figure. RV 6.4 Resistance plate force change at the intermediate crack element

RV 6.1.1.4 Anchorage analysis

RV 6.1.1.4.1 General (RV 1) The anchorage analysis may be conducted at the bending crack closest to the point of zero moment, in accordance with Section Error: Reference source not found or at any intermediate crack element in accordance with Section Error: Reference source not found. A link may be arranged in the

34


anchorage zone and an analysis conducted in accordance with Section Error: Reference source not found.

RV 6.1.1.4.2 Anchorage at the bending crack closest to the point of zero moment (RV 1) The analysis shall be conducted at the bending crack closest to the point of zero moment, which is where the bending moment equals the cracking moment in accordance with Equation Error: Reference source not found (see also Error: Reference source not found). The location of the bending crack closest to the point of zero moment shall be obtained under design loads in the ultimate limit state and without taking the magnitude of shift of tension envelope into account.

35


Biegeriss, der dem Momentennullpunkt am nächsten Ist

Bending crack closest to the point of zero moment

versetzte Zugkraftlinie Offset resistance to tension curve

Widerstand Resistance

Zugkraftlinie Betonstahl Resistance to tension curve of reinforcing steel

Nachweis der Zugkraftdeckung für Betonstahl nach DIN EN 1992-1-1

Analysis of curtailment of longitudinal tension reinforcement for reinforcing steel in accordance with DIN EN 1992-1-1

Biegeriss, der dem Momentennullpunkt am nächsten ist


Nachweis der Zugkraftdeckung CFK-Lamelle Analysis of resistance to tension of CFRP plate

36


Zugkraftlinie Resistance to tension curve

Nachweis der Zugkraftdeckung Betonstahl Analysis of resistance to tension of reinforcing steel

Figure RV 6.5: Schematic presentation of anchorage analysis for CFRP plates (RV 2) The prestrain of the reinforcement from the reinforcement load must not be taken into account in this analysis.

(RV 3) At the bending crack closest to the point of zero moment, the acting moment shall be smaller than the resistance moment in accordance with Equation Error: Reference source not found, where the magnitude of shift of tension envelope in accordance with DIN EN 1992-1-1, Section 9.2.1.3 or DIN EN 1992-1-1, Section 9.3.1.1 shall be taken into account.

M Ed≤M Rd( lbL) (RV 6.20)(RV 4) The resistance moment shall be calculated as a function of the strains of the reinforcement strands by means of Equation Error: Reference source not found. The compression zone height and the internal lever arm may be determined at the bending crack closest to the point of zero moment, or approximated by means of the equations in Annex RV L 1.

M Rd (lbL )=ε LRka (lbL )⋅ELm⋅AL⋅zL

a⋅ 1γ BA

+ε sRka ( lbL )⋅E s⋅A s⋅zs

a⋅ 1γ S (RV 6.21)

(RV 5) The strains of the CFRP plate are calculated using Equation Error: Reference source not found.

ε LRka ( l bL)={sin( π

2⋅

lbL

l bL,lim)⋅εLRk,lim

a für 0<lbL<lbL,lim

εLRk,lima für lbL,lim≤lbL (RV 6.22)

With strain as a function of maximum bond strength in accordance with Section Error: Reference source not found.

ε LRk,lima =0 . 985⋅

f bLk,max

ELm (RV 6.23)and the corresponding anchorage length as a function of effective bond length in accordance with Section Error: Reference source not found.

lbL,lim=0 .86⋅l bL,max (RV 6.24)(RV 6) The strains of the reinforcing steel are calculated using Equation Error: Reference source not found with factor N = 0.25 for ribbed reinforcing steel and N = 0 for smooth steel. For good bond conditions, VB = 1 shall be used in Equation Error: Reference source not found, and for medium bond conditions, VB = 0.7.

ε sRka ( lbL )=κVB⋅κbsk⋅(sLr

a (lbL) )(α N+1)/2⋅( da−xa

d La−xa )(

α N+1)/2¿

f yk

Es (RV 6.25)Where:

sLra slippage of plate in mm in accordance with Equation Error: Reference source not

foundda effective static depth of inner reinforcement in mm dL

a effective static depth of bonded reinforcement in mm xa compression zone height in mm

(RV 7) The slippage of the plate shall be calculated in accordance with Equation Error: Reference source not found.

37


sLra ( lbL )={0 ,213 mm⋅(1−cos ( π2⋅ lbL

lbL,lim )) für 0<lbL≤lbL,lim

0 ,213 mm+(lbL−lbL,lim )⋅εLRk,lima für lbL,lim≤lbL (RV 6.26)

(RV 8) The bond coefficient for reinforcement embedded in concrete is obtained by means of Equation Error: Reference source not found with factors in accordance with Error: Reference source not found. Only one bar with spare bar diameter shall be used for double bars. The spare bar diameter is

obtained by φN=√2⋅φ .

κbsk=κ b1k⋅√ f cmκb2

Es ¿φκ b3¿ (ELm ¿t L)

κ b4(RV 6.27)

Where:fcm mean cylinder compressive strength of the concrete in N/mm² greatest reinforcing steel diameter in mm Es mean modulus of elasticity of the reinforcing steel (may be assumed to be 200 000

N/mm²) in N/mm²ELm mean modulus of elasticity of the plate in N/mm²

tL plate thickness in mm

Table RV 6.2: Bond coefficients for CFRP plates

Column 1 2 3

LineReinforcement embedded in concrete

Ribbed Smooth

1 b1k 2.545 1.2922 b2 1.0 1.33 b3 0.8 1.04 b4 0.2 0.3

RV 6.1.1.4.3 Anchorage at any intermediate crack element (RV 1) Alternatively, the anchorage analysis may be conducted at any intermediate crack element. Here, the magnitude of shift of tension envelope in accordance with DIN EN 1992-1-1, Section 9.2.1.3 or DIN EN 1992-1-1, Section 9.3.1.1 shall be taken into account.

(RV 2) At the location of the bending crack, the concentrated plate force taking into account the magnitude of shift of tension envelope shall be smaller than the resistance plate force in accordance with Equation Error: Reference source not found.

FLEd≤FbLRd (RV 6.28)(RV 3) The resistance plate force may be obtained by means of Equation Error: Reference source not found as a function of crack spacing in accordance with Equation Error: Reference source not found. The bond strength fbLd shall be obtained by means of Equation Error: Reference source not found, with lbL to be substituted with crack spacing sr.

FbLRd=bL⋅tL⋅f bLd (sr ) (RV 6.29)(RV 4) In calculating the concentrated plate force, the prestrain of the reinforcement from the reinforcement action may only be taken into account if — prior to reinforcement — the component is already in the cracked state at the anchorage analysis point.

RV 6.1.1.4.4 Anchorage with curtailment of link

RV 6.1.1.4.4.1 General (RV 1) If the plate is curtailed by one or more bonded links, it only needs to be demonstrated that the plate force at the last bonded link is smaller than the resistance force in accordance with Equation

38


Error: Reference source not found. Here, the magnitude of shift of tension envelope in accordance with DIN EN 1992-1-1, Section 9.2.1.3 or DIN EN 1992-1-1, Section 9.3.1.1 shall be taken into account.

FbLRd=bL⋅tL⋅f bLd ( lbL)+ΔFL, 1

γ BA (RV 6.30)(RV 2) The bond length in Equation Error: Reference source not found shall be obtained in accordance with Error: Reference source not found. The potential increase in plate force FL,1 due to curtailment of link may be calculated in accordance with Section Error: Reference source not found.

Figure RV 6.6: Bond length of curtailed CFRP plates

RV 6.1.1.4.4.2 Bond strength increase due to curtailment of link Calculation of ΔFL,1 for CFRP plates or steel tabs with steel link curtailment

(RV 1) The prerequisite for application of bond strength increase due to curtailment of link is steel tab links that were executed in accordance with Section Error: Reference source not found Curtailments made of CF sheeting require rules in the respective approval. If using the bond strength increase, the flexural tension steel tabs/CFRP plates shall be arranged symmetrically to the web axis.

(RV 2) For two or more CFRP plates or steel tabs, the bond strength increase FL,1 refers to the sum of the plate forces.

(RV 3) The increase in resistance plate tensile strength FL,1 — taking into account the crack opening curtailment by link — shall be obtained by means of Equation Error: Reference source not found.

ΔF L,1=tL⋅bL⋅bLw

120⋅√ f ctm,surf

1.33⋅[230⋅κl⋅

Fu( αb )bL⋅bLw

−23⋅(κl⋅Fu( αb )bL⋅bLw

)2 ]

(RV 6.31)Where:

tL plate thickness [mm]bL plate width [mm]bLw width of the curtailment link [mm]l = 1 for steel or CFRP cross-sections of a tab or plate l = 0.48 for two or more CFRP plate cross-sections bonded side-by-side l = 0.52 for two or more steel tab cross-sections bonded side-by-side Fu(b) in accordance with Equation Error: Reference source not found [N]

(RV 4) Bond strength increase due to curtailment of link may be calculated for all values of 0.4 ≤ αb = bL / bw ≤ 0.8. For all values of αb ≤ 0.4 Δ FL,1 cannot be calculated. For all values of αb > 0.8 limit value calculation of αb = 0.8 shall apply.

(RV 5) If bonding several flexural strength steel tabs/CFRP plates with centre distance sL, αb may be calculated using equivalent plate/tab width bL,eff. The equivalent width is obtained from the maximum edge distance of the flexural tensile reinforcement in accordance with Error: Reference source not found. When using this effective plate/tab width, the resistance increase FL,1,eff shall be reduced as the

39


result from Equation Error: Reference source not found using the ratio of actual plate width to effective plate width in accordance with Equation Error: Reference source not found.

ΔF L,1=ΔFL,1,eff⋅∑ bL

bL,eff (RV 6.32)

Figure RV 6.7: Bridging joist with several bonded CFRP plates or steel tabs

(RV 6) After determining the total link stiffness EIS,g by means of Equations Error: Reference source notfound and Error: Reference source not found possibly taking into account the curtailment angle and an adhesive layer thickness tG ≥ 1 mm between the steel tab curtailments, the crack opening curtailment Fu(αb) shall be obtained for all αb- values from 0.4 ≤ αb ≤ 0.8 by means of Equation Error: Reference source not found. The force needed for crack opening curtailment shall be taken into account in the actions on the link.

Fu(αb )=Fu,2⋅( 0 . 8−αb

0 .4 )+Fu,4⋅(αb−0. 40 .4 ) [N] (RV 6.33)

Where:b =bL/bw bw joist width [mm]Fu,2 Equation Error: Reference source not found [N]Fu,4 Equation Error: Reference source not found [N]

(RV 7) The crack opening curtailment Fu,2 shall be obtained by means of Equation Error: Reference source not found.

Fu,2=2⋅24⋅EI s,g,αb=0,4

(3⋅α−4⋅α 3)⋅l23

¿w1+26 400⋅EIs,g, αb=0,4

11 000⋅l13+2,4⋅EI s,g,αb=0,4 [N] α=

0 .3⋅bw−20bw−40 (RV 6.34)

w1=w−(1− EI s,g, α b=0 . 4

4 583⋅l13+EIs,g, αb=0 . 4 )¿0 .1 [mm] (RV 6.35)

Where:l1 = 0.3 ∙ bw – 20 [mm]l2 = bw - 40 [mm]w = 0.35 for CFRP plates w = 0.25 for steel tabs EIs,g,αb=0.4 for a curtailment angle in accordance with (RV 12)

without curtailment angle in accordance with (RV 13)

40


Detail Detail

Figure RV 6.8: Bridging joist with bonded CFRP plate or steel tab for b = 0.4(RV 8) The crack opening curtailment Fu,4 shall be obtained by means of Equation Error: Reference source not found.

Fu,4=48⋅EI s,g,α b=0 . 8

l 43

¿w2+26 400⋅EI s,g, αb=0 .8

11 000⋅l33+2 .4⋅EIs,g, αb=0 . 8 [N] (RV 6.36)

w2=w−(1− EIs,g,α b=0 . 8

4 583⋅l33+EI s,g,αb=0 . 8 )¿0 .1 [mm] (RV 6.37)

Where:l3 =20 + tLW [mm]l4 =2 ∙ l3 [mm]w = 0.35 for CFRP platesw = 0.25 for steel tabsEIs,g,αb=0.8 for a curtailment angle in accordance with (RV 12)

without curtailment angle in accordance with (RV 13)

Figure RV 6.9: Bridging joist with bonded CFRP plate or steel tab for b = 0.8

Total flexural stiffness EIS,g

(RV 9) Flexural stiffness EIS,j is composed of the link stiffness EIS and the adhesive stiffness EIG per bond zone. As the flexural stiffness of the adhesive is very low, it will be neglected in further calculations. The flexural stiffness EIS of a bond zone (detail A or detail B) shall be obtained by means of Equation Error: Reference source not found.

EI S=∑ ES⋅(I S+AS⋅zS2) (RV 6.38)Where:

41


IS sectional moment of inertia of a steel link [mm4]AS sectional area of a steel link [mm2]ES modulus of elasticity of the steel link [N/mm2]zS distance of the centroidal axis of the sectional area of the steel to the total sectional

area [mm](RV 10) Calculation of flexural stiffness in zone A using two sectional areas of steel by means of Equation Error: Reference source not found will yield stiffness EIS,A:

Detail Detail

Figure RV 6.10: Detail A for calculating flexural stiffness in zone A

EI S,A=2⋅ES⋅( I S+AS⋅z S2) (RV 6.39)Where:

zs=1

2⋅tLW+0 .5

[mm](RV 11) For zone B with 3 sectional areas of steel and 2 bonded joints, EIS,B shall be obtained by means of Equation Error: Reference source not found.

Detail Detail

Figure RV 6.11: Detail B for calculating flexural stiffness in zone B

EI S,B=2⋅ES⋅( I S+AS⋅zS2)+ES I S (RV 6.40)Where:

zs=tLW+1 [mm](RV 12) The flexural stiffness EIS,g of the link for different stiffness values of individual link sections shall be calculated for b = 0.4 in accordance with Equation Error: Reference source not found and for b = 0.8 in accordance with Equation Error: Reference source not found.

EI s,g,αb=0. 4=2⋅EI S,A¿EI S,B

EI S,A+EI S,B [N/mm2] (RV 6.41)

EI s,g,αb=0. 8=2⋅EI S,A¿ES I S

EI S,A+ES I S [N/mm2] (RV 6.42)(RV 13) If link sections A and B have the same stiffness, thus not requiring a curtailment angle, the stiffness EIS,g,αb=0.4 shall be obtained by means of Equation Error: Reference source not found and for stiffness EIS,g,αb=0.8, the same link stiffness shall be used.

42


RV 6.1.1.4.5 Mechanical anchorage (RV 1) To increase anchorage force, mechanical anchorage systems may be used for bonded CFRP plates, assuming the respective approvals.

(RV 2) If a mechanical anchorage is used, the anchorage analysis may be conducted in accordance with Section Error: Reference source not found of this Guideline. This analysis shall use the anchorage system force that can be anchored for FbLRd.

(RV 3) The mechanical anchorage forces that can be anchored can also be assumed as the maximum plate force in flexural load-bearing capacity analysis in accordance with Section Error: Reference source not found. Here, the strains of the plate in the ultimate limit state in accordance with Section Error: Reference source not found (RV10) shall be analysed. Alternatively, an analysis of the bond subject to infrequent combination of actions may be conducted in accordance with Section Error: Reference source not found (RV11).

RV 6.1.1.5 Localised reinforcements(RV 1) For localised reinforcements, the bond length on both sides of the required reinforcement zones shall be equivalent to at least the component thickness plus anchorage length lbL,max in accordance with Equation Error: Reference source not found. Only tensile forces equivalent to the maximum resistance bond breakage force FbLRd,max at the individual crack in accordance with Equation Error: Reference source not found may be allocated to the adhesive bond reinforcement.

FbLRd,max=f bLk,max⋅bL⋅tL

γBA (RV 6.43)(RV 2) If the bonded reinforcement is enclosed by links, tensile forces equivalent to the resistance bond breakage force at the individual crack may be allocated to the adhesive bond reinforcement, taking into account the bond strength increase due to curtailment of link in accordance with Equation Error: Reference source not found.

RV 6.1.2 Reinforcement with bonded steel tabs for components predominantly subject to bending stress

RV 6.1.2.1 Assumptions (RV 1) In addition to flexural load-bearing capacity analysis in accordance with Section Error: Reference source not found and the bond analysis in accordance with Section Error: Reference source not found, a shear resistance analysis in accordance with Section Error: Reference source not found and an analysis to prevent breakage due to shift in accordance with Section Error: Reference source not found shall be conducted.

(RV 2) As an alternative to the bond analysis in accordance with Section Error: Reference source not found, an analysis similar to Section RV 6.1.1.4.4 may be conducted if the resistance force according to Equation Error: Reference source not found is greater than the maximum tensile force in the total system.

FbLRd≥FLd,max≥ f Lyd⋅A L (RV 6.44)

RV 6.1.2.2 Analysis of flexural load-bearing capacity(RV 1) Within the yield point of the steel tabs, the full contribution of the existing reinforcement and the steel tabs may be assumed in the ultimate limit state, provided a bond strength analysis was conducted. The strain state of the existing reinforcement of reinforced concrete components at the time of adhesive bonding may be determined on the assumption of the cracked state. An analysis of longitudinal shear between tendon cross-sections shall be conducted in accordance with DIN EN 1992-1-1, Section 6.2.4.

(RV 2) For steel tabs, a modulus of elasticity of 200 000 N/mm² may be used for calculation.

(RV 3) The strain of the steel tabs must not exceed 3 mm/m.

RV 6.1.2.3 Bond analysis (RV 1) The analysis shall be conducted at the bending crack closest to the point of zero moment, which is where the bending moment equals the cracking moment in accordance with Equation Error:

43


Reference source not found (see also Error: Reference source not found). The location of the bending crack closest to the point of zero moment shall be obtained under design loads in the ultimate limit state and without taking the magnitude of shift of tension envelope into account.

44


Biegeriss, der dem Momentennullpunkt am nächsten Ist


versetzte Zugkraftlinie Offset resistance to tension curve

Widerstand Resistance

Zugkraftlinie Betonstahl Resistance to tension curve of reinforcing steel

Nachweis der Zugkraftdeckung für Betonstahl nach DIN EN 1992-1-1

Analysis of curtailment of longitudinal tension reinforcement for reinforcing steel in accordance with DIN EN 1992-1-1

Biegeriss, der dem Momentennullpunkt am nächsten ist


Nachweis der Zugkraftdeckung CFK-Lamelle Analysis of curtailment of longitudinal tension reinforcement for CFRP plate

45


Zugkraftlinie Resistance to tension curve

Nachweis der Zugkraftdeckung Betonstahl Analysis of curtailment of longitudinal tension reinforcement for reinforcing steel

Figure RV 6.12: Schematic presentation of anchorage analysis for steel tabs

(RV 2) The prestrain of the reinforcement from the reinforcement load must not be taken into account in this analysis.

(RV 3) At the bending crack closest to the point of zero moment, the acting moment shall be smaller than the resistance moment in accordance with Equation Error: Reference source not found, where the magnitude of shift of tension envelope in accordance with DIN EN 1992-1-1, Section 9.2.1.3 or DIN EN 1992-1-1, Section 9.3.1.1 shall be taken into account.

M Ed≤M Rd( lbL) (RV 6.45)(RV 4) The resistance moment shall be calculated as a function of the strains of the reinforcement strands. The compression zone height and the internal lever arm may be determined at the bending crack closest to the point of zero moment, or approximated by means of the equations in Annex RV L 1.

MRd (lbL )=ε LRka (lbL )⋅ELm⋅AL⋅zL

a⋅ 1γBA

+ε sRka ( lbL )⋅E s⋅A s⋅zs

a⋅ 1γ S (RV 6.46)

(RV 6) The strains of the steel tabs are obtained by means of Equation Error: Reference source not found.

ε LRka ( l bL)={sin( π

2⋅

lbL

lbL,lim)⋅εLRk,lim

a für 0<lbL<lbL,lim

εLRk,lima für lbL,lim≤lbL

≤f Lyk

EL

(RV 6.47)With strain as a function of maximum bond strength in accordance with Section Error: Reference source not found

ε LRk,lima =0 .906⋅

f bLk,max

ELm (RV 6.48) and the corresponding anchorage length as a function of effective bond length in accordance with Section Error: Reference source not found.

lbL,lim=0 ,79⋅lbL,max (RV 6.49)(RV 7) The strains of the reinforcing steel are calculated using Equation Error: Reference source not found with factor N = 0.25 for ribbed reinforcing steel and N = 0 for smooth steel. For good bond conditions, vb = 1 shall be used in Equation Error: Reference source not found and for medium bond conditions, vb = 0.7.

ε sRka ( lbL )=κVB⋅κbsk⋅(sLr

a (l bL) )(α N+1)/2⋅( da−xa

dLa−xa )(

αN+1)/2¿

f yk

Es (RV 6.50)Where:

sLra slippage of plate in mm in accordance with Equation Error: Reference source not

foundda effective static depth of inner reinforcement in mm dL

a effective static depth of bonded reinforcement in mm xa compression zone height in mm

46


(RV 8) The slippage of the plate shall be calculated in accordance with Equation Error: Reference source not found.

sLra ( lbL )={0. 195 mm⋅(1−0 .82⋅cos( π

2⋅

lbL

lbL,lim )) for 0<lbL≤lbL,lim

0 . 195 mm+( lbL−l bL,lim )⋅εLRk,lima for l bL,lim≤lbL (RV 6.51)

(RV 9) The bond coefficient for reinforcement embedded in concrete is obtained by means of Equation Error: Reference source not found with factors in accordance with Error: Reference source not found. Only one bar with spare bar diameter shall be used for double bars. The spare bar diameter is

obtained by φN=√2⋅φ .

κbsk=κ b1k⋅√ f cmκb2

Es ¿φκ b3¿ (ELm ¿t L)

κ b4(RV 6.52)

Where:fcm mean cylinder compressive strength of the concrete in N/mm² greatest reinforcing steel diameter in mmEs mean modulus of elasticity of the reinforcing steel (may be assumed to be 200,000

N/mm²) in N/mm²

ELm mean modulus of elasticity of the plate in N/mm²

tL plate thickness in mm

Table RV 6.3: Bond coefficients for steel tabs

Column 1 2 3Line Reinforcement embedded

in concreteRibbed Smooth

1 b1k 11.9 7.72 b2 1.2 1.83 b3 0.7 1.04 b4 0.5 0.7

RV 6.1.2.4 Localised reinforcements (RV 1) For localised reinforcements, the bond length on both sides of the required reinforcement zones shall be equivalent to at least the component thickness plus anchorage length lbL,max in accordance with Equation Error: Reference source not found. Only tensile forces equivalent to the maximum resistance bond breakage force FbLRd,max at the individual crack in accordance with Equation Error: Reference source not found may be allocated to the adhesive bond reinforcement.

FbLRd,max=f bLk,max⋅bL⋅tL

γBA (RV 6.53)(RV 2) If the bonded reinforcement is enclosed by links, tensile forces equivalent to the resistance bond breakage force at the individual crack may be allocated to the adhesive bond reinforcement, taking into account the bond strength increase due to curtailment of link in accordance with Equation Error: Reference source not found.

RV 6.1.3 Bending reinforcement using CFRP plates bonded in indent cuts

RV 6.1.3.1 Assumptions (RV 1) In addition to a bending analysis in accordance with Section Error: Reference source not found and an anchorage analysis in accordance with Section Error: Reference source not found, a shear resistance analysis in accordance with Section Error: Reference source not found and an analysis to

47


prevent breakage due to shift in accordance with Section Error: Reference source not found shall be conducted.

(RV 2) If the bending reinforcement is to be designed for not predominantly static loads, a fatigue analysis in accordance with Section Error: Reference source not found shall be conducted.

RV 6.1.3.2 Analysis of flexural load-bearing capacity (RV 1) The strain of the CFRP plate must not exceed value LRd,max according to Equation Error: Reference source not found.

εLRd,max≤κ ε⋅εLud (RV 6.54)Where:

ε = 0.8(RV 2) The effective static depth dL of the CFRP plates shall be assumed in accordance with Equation Error: Reference source not found.

d L=h−( t s−bL

2 ) (RV 6.55)(RV 3) The maximum tensile force with consideration of factor ε shall be obtained by means of Equation Error: Reference source not found.

FLRd=κ ε⋅f Luk

γ LL⋅A L

(RV 6.56)(RV 4) Within the strains in accordance with DIN EN 1992-1-1, 6.1 and Section Error: Reference source not found (RV1) of this Guideline, the full contribution of the existing reinforcement and the CFRP plates may be assumed in the ultimate limit state. The strain state of the existing reinforcement of reinforced concrete components at the time of adhesive bonding may be determined on the assumption of the cracked state.

RV 6.1.3.3 Analysis of bond load capacity, resistance to tension(RV 1) Resistance to tension in the ultimate limit state over the entire component length shall be assessed (Error: Reference source not found). The resistance to tension curve taking into account the magnitude of shift of tension envelope shall be obtained in accordance with DIN EN 1992-1-1, Section 9.2.1.3(2) or 9.3.1.1(4). Different strains of the individual reinforcement layers and grading of reinforcing steel cross-sections shall be taken into account. The plate tensile force that can be anchored by means of the bond between CFRP plate and concrete part shall be obtained by means of Equation Error: Reference source not found for bond lengths lb up to 115 mm, and for longer bond lengths by means of Equation Error: Reference source not found.

Für l bL≤115 mm : FbLRd=bL⋅τbLd⋅4√ar⋅lbL⋅(0 . 4−0 .0015⋅lbL )⋅0.95 (RV 6.57)

Für lbL>115 mm : F bLRd=bL⋅τ bLd⋅4√ar⋅(26 .2+0 .065⋅tanh ( ar

70 )⋅(lbL−115))⋅0 .95(RV 6

.58)Where:

FbLRd design bond load capacity per plate in NlbL anchorage lengths of the plate in accordance with Error: Reference source not

found in mmbLd design shear load capacity of the adhesive according to Equation Error: Reference

source not found

bL CFRP plate width in mm

ar distance from the longitudinal axis of the plate to the free component edge in mm, ar may be max. 150 mm in the calculation

(RV 2) In each cross-section of the reinforced component, it shall be ensured that the design resistance of the component is greater than the design structural action in the reinforced state. The

48


partial tensile forces of the reinforcement strands shall be determined under the assumption of even distribution of strain. Analysis of curtailment of longitudinal tension reinforcement in accordance with Error: Reference source not found may be conducted taking into account the relevant provisions of EN 1992-1-1, Section 9.2.1.3(2) or 9.3.1.1(4). In particular, the analysis of resistance to tension of existing reinforcing steel in the areas where the CFRP plates cannot be included (according to Error: Reference source not found by simplified approach to Point A) shall be conducted in accordance with EN 1992-1-1.

49


Ermittlung der Zugkraftanteile (exemplarisch) Determining the tensile force components (example)

versetzte Zugkraftlinie Offset resistance to tension curveNachweis der Zugkraftdeckung Betonstahl Analysis of resistance to tension of reinforcing

steel Zugkraftlinie Betonstahl Resistance to tension curve of reinforcing steelNachweis der Zugkraftdeckung für Betonstahl nach DIN EN 1992-1-1

Analysis of resistance to tension of reinforcing steel in accordance with DIN EN 1992-1-1

Nachweis der Zugkraftdeckung CFK-Lamelle Analysis of resistance to tension of CFRP plate Zugkraftdeckungslinie der CFK-Lamellen nach Gin. (6.36) und (6.37)

Resistance to tension curve of CFRP plates according to (6.36) and (6.37)

Figure RV 6.13: Anchorage analysis for CFRP plates bonded in indent cuts

50


RV 6.1.4 Column reinforcement using confinement

RV 6.1.4.1 General (RV 1) Confinement may be used to add to shear reinforcement that is structurally required and to allow calculation in accordance with DIN EN 1992-1-1 (see Section 9.5).

(RV 2) Confinement can be used for round columns and also to activate the multiaxial strength of the column concrete. The corresponding calculation method is described in the following Section Error: Reference source not found.

(RV 3) Due to the higher loads, confined compression members will shorten more than link-reinforced compression members. The effects of these greater deformations on adjacent components may have to be taken into account.

RV 6.1.4.2 Round supports with activation of multiaxial strength(RV 1) To ensure the activation of multiaxial strength of the concrete, the calculated thickness tL, which is the sheeting thickness multiplied with the number of layers shall not be less than the value obtained by means of Equation Error: Reference source not found.

tL≥[ k0 ]⋅D⋅f cm2

EL (RV 6.59)(RV 2) The design loadbearing capacity NRd of reinforced concrete supports with a round cross-section, rotationally symmetrical reinforcing steel longitudinal reinforcement and full-area confinement with carbon fibre sheeting in accordance with Section Error: Reference source not found, and which are subjected to eccentric design forces, may be obtained by means of Equations Error: Reference source not found and Error: Reference source not found for Parameters Error: Reference source not found, Error: Reference source not found and Error: Reference source not found.

D≥120 mm (RV 6.60)λ≤40 (RV 6.61)e0

D≤0 . 25

(RV 6.62)

f cm≤58 N /mm2(RV 6.63)

(RV 3) Factors [k0] to [k9] are construction kit-specific values that can be found in the general building inspectorate approval. Guideline values for pre-dimensioning can be found in Annex RV K.

(RV 4) The geometric variables of the confined support cross-section may be obtained according to Error: Reference source not found.

51


verschmierte Betonstahlbügel- bzw. wendelbewehrung

loaded reinforcing steel link or hoop

Umschnürung mit CFK-Gelegen confinement using CFP sheeting

Figure RV 6.14 Cross-section of the confined reinforced concrete column

(RV 5) The loadbearing capacity of the column may be obtained by means of Equation Error: Reference source not found. The referenced angle shall be obtained according to Error: Reference source not found, which describes the tension block in the confined cross-section taking into account time-dependent and second order effects. It shall be obtained from the combined actions of design axial force NEd and the bending moment MEd according to first order by means of Equations Error: Reference source not found and Error: Reference source not found as well as by iteration.

NRd=1

γLG⋅θ⋅α 1⋅f cck⋅Ac⋅(1−sin (2⋅π⋅θ )

2⋅π⋅θ )+ 1γ s⋅(θc−θ t )⋅f syk⋅A s

(RV 6.64)

NRd⋅(e tot+l2

π2⋅ξ1⋅ξ2⋅φbal⋅K ϕ)=1γLG⋅23⋅α1⋅f cck⋅Ac⋅

D2⋅(sin3 (π⋅θ )

π )+1γ s⋅f syk⋅As⋅

D2⋅sin (π⋅θc )+sin (π⋅θt )π (RV 6.65)

Where:l length of the compression member 1 factor taking into account the reduction in curvature with an increase in

compressive force Nu 2 factor taking into account the geometry of the compression member and strain of

the confining reinforcement

52


Figure RV 6.15: Schematic presentation of simplified design of sections (RV 6) Stress-strain relations for the design of sections of the reinforced concrete support confined with CF sheeting, links or hoops, the completeness factor 1 of the tension block may be obtained by means of the following equation.

α 1=1.17−0. 2⋅f cck

f ck¿ (RV 6.66)(RV 7) The characteristic compressive strength of confined concrete may be determined as a function of the properties of the CF sheeting and the link or hoop.

f cck=f ck+[k1 ]⋅[E jl⋅ε juk+( ρwy⋅f wyk−Δp )⋅( D c−sw

2D )

2](RV 6.67)

(RV 8) The stiffness of the CF sheet confinement relative to column diameter D may be obtained by means of Equation Error: Reference source not found. This will yield a calculated thickness tL of the confinement from the number of layers multiplied with the calculated sheeting thickness.

E jl=2⋅EL⋅tL

D (RV 6.68)(RV 9) To determine the characteristic strain of the confined reinforcement, the restraints of the component r, the ambient conditions temperature and humidity T and F, the type action E and the duration of the action in the ultimate limit state Z will be taken into account in the minuend of the following equation. Furthermore, the subtrahend will take into account the time-dependent influences from the previous actions that will reduce the loadbearing capacity. The longitudinal deformation of the reinforced concrete column cc(t) from creep resulting in strain of the CF sheeting, which can be determined in a simplified approach for shear strain = 0.2, is deemed a state of internal stress reducing loadbearing capacity. Factor k = 1.5 takes into account the greater spread of the creep deformation of confined members.

ε juk=α r⋅α T⋅αF⋅αE⋅aZ⋅ε Lk−αk⋅ν⋅εcc (Δt ) (RV 6.69)α r=[k 2] (RV 6.70)αT=[ k3 ] (RV 6.71)αF=[k 4 ] (RV 6.72)α E=[k5 ] (RV 6.73)αZ=[ k6 ] (RV 6.74)k = 1.5 (RV 6.75)

53


(RV 10) The approaches to creep in confined concrete are based on the creep approach in accordance with DIN EN 1992-1-1:2005-10, which was modified for concrete confined with CF sheeting.

ε cc (Δt )=[k7 ]⋅βc (Δt )⋅β ( f cm )⋅β0,k⋅σcp

Ecm (RV 6.76)(RV 11) The approach of using the factor to describe development over time c(t) allows taking into account short residual life spans from the time of reinforcement. βc (Δt )=1 for common reinforcement purposes (RV 6.77)

βc (Δt )=[ Δt /1,7β H+Δt /1,7 ]

0,3

for reinforcement on components for short residual life spans (RV 6.78)

(RV 12) Due to full area confinement using CF sheeting, value H to describe the effect of humidity may be selected independent of the air humidity.

βH=250 for f cm≤35 N/mm2(RV 6.79)

βH=250⋅α 3 for f cm>35 N/mm2(RV 6.80)

α 3=[35f cm ]

0,5

(RV 6.81)(RV 13) Factor (fcm) describes the influence of concrete compressive strength at the time of reinforcement. The concrete compressive strength at the time of load application may differ from the 28-day strength fcm due to post-setting.

β ( f cm)=16 ,8√ f cm (RV 6.82)

(RV 14) If the creep compressive stress cp exceeds 45 % of concrete compressive strength fcm(tV0) at the time of reinforcement tV0, non-linear effects shall be taken into account.

β0,k=e (2,7⋅(k σ−0, 45 ))

for k σ>0 . 45 (RV 6.83)

β0,k=1 for k σ≤0 . 45 (RV 6.84)

k σ=σcp

f cm (RV 6.85)(RV 15) The creep compressive stress is obtained from the quasi-permanent actions in the serviceability limit state, the axial force NEqp first order moment MEqp taking into account planned and accidental eccentricity e0 and ei, using theoretical section variables Ai and Ii.

σ cp=|NEqp

A i|+|

M Eqp

Ii⋅2D

|

(RV 6.86)Ai=Ac+(α s−1 )⋅As (RV 6.87)

α s=E s

Ecm (RV 6.88)

I i=I c+(α s−1)⋅∑ jzs

j2⋅A s

j(RV 6.89)

(RV 16) To determine the linear elastic deformation reference value, secant modulus of elasticity Ecm of the concrete subject to axial compressive action at the time of reinforcement tV0 in accordance with DIN EN 1992 1-1 may be used. (RV 17) To determine the confining effect of the reinforcing steel reinforcement, the reinforcement

54


degree wy is required, which shall be obtained using calculated thickness tw,eff of the loaded link or hoop reinforcement:

ρwy=2⋅tw,eff

Dc (RV 6.90)

tw,eff=Asw

2⋅sw (RV 6.91)(RV 18) Due to the different effective areas of the confined reinforcement made of reinforcing steel and CF sheeting, the uneven distribution of shear compression across the cross-section shall be taken into account.

p1=E jl⋅ε juk (RV 6.92)

p2=2⋅(EL⋅tL⋅ε juk+t w,eff⋅f wyk)−p1⋅c

Dc+c (RV 6.93)

Δp=p1−2⋅EL⋅tL⋅ε juk− ( p1+ p2 )⋅c

D c (RV 6.94)(RV 19) Indicator f *ck of the simplified stress-strain relations for the design of sections may be obtained using shear compression difference p. The second parenthesis in the following equation takes into account that the different legs of the link or hoop reinforcement arranged at spacing s form compression curves that will reduce the effective area of this confining reinforcement.

f ck¿=f ck+[k1 ]⋅[ ρwy⋅f wyk−Δp ]⋅(Dc−sw

2D )

2

(RV 6.95)(RV 20) The referenced angles c and t describe the distribution of stress in the loaded reinforcing steel longitudinal reinforcement in rotationally symmetrical arrangement.

0≤θc=1.25⋅θ−0 .125≤1 (RV 6.96)

0≤θt=1 .125−1 .5⋅θ≤1 (RV 6.97)(RV 21) First order eccentricity etot consists of planned eccentricity e0 and additional accidental eccentricity ei in accordance with DIN EN 1992-1-1.e tot=e0+ei (RV 6.98)(RV 22) Factor 1 approximates the reduction in component curvature if longitudinal compressive force increases.

ξ1=N balk

N Rk=

0 . 8⋅f cck⋅Ac

N Rd⋅γ c≤1

(RV 6.99)(RV 23) Factor 2 takes into account the geometry of the compression member and strain due to confinement.

ξ2=1. 15+0 . 06⋅ρ ε−(0 . 01+0 . 012⋅ρs )⋅lD≤1

(RV 6.100)

ρ ε=ε juk

εc2 (RV 6.101)(RV 24) The following equation for maximum curvature of the confined cross-section applies to sections in rotationally symmetrical arrangement.

φbal=2⋅εcu+ε yk

D+Dc−(2⋅φw+φs ) (RV 6.102)

55


ε cu=εc2⋅(1 .75+19⋅E jl⋅ε juk

f cm)

(RV 6.103)

ε yk=f syk

Es (RV 6.104)Where:

c2 linear strain of concrete subject to unconfined compression upon reaching of compressive strength: c2 = 0.002

(RV 25) Factor K according to DIN EN 1992-1-1, Equation (5.37) takes into account the increase in curvature due to time-dependent creep through linear increase using effective creep ef. Effective creep ef in Equation (5.37) shall be obtained by means of Equation Error: Reference source not found.

ϕef= [k7 ]⋅16 , 8

√ f cm [N/mm2]⋅β0,k

M Eqp

M Ed (RV 6.105)

6.2 Shear force

6.2.1 Analysis(RV 10) In principle, shear resistance shall be in accordance with DIN EN 1992-1-1, Section 6.2. For components with bonded bending reinforcement in accordance with RV 6.1.1 and RV 6.1, additional requirements in accordance with Sections 6.2.3 (RV 10) through (RV 12) shall apply.

(RV 11) If a shear resistance analysis according to this section cannot be conducted, shear reinforcement in accordance with Section Error: Reference source not found may be executed.

6.2.2 Members not requiring design shear reinforcement(RV 7) When determining the design shear reinforcement VRd,C in accordance with DIN EN 1992-1-1, Section 6.2.2, the bonded reinforcement must not be allocated to the tension reinforcement area AsL.

6.2.3 Members requiring design shear reinforcement(RV 9) For old components, care should be taken that according to DIN EN 1992-1-1, Section 9.2.2 (4), the 3-fold area is covered by links. If this requirement has not been satisfied, the difference shall be covered using bonded links in accordance with Section Error: Reference source not found.

(RV 10) For components with bonded bending reinforcement in accordance with Sections RV 6.1.1 and RV 6.1.2, if the limit according to Equation Error: Reference source not found is exceeded, links in accordance with (RV 11) shall be executed.

V Ed⋅σsw

V Rd,max≤{75 N/mm² for ribbed links

25 N/mm² for smooth links (RV 6.106)Where:

VEd design shear forceVRd,max design shear resistance in accordance with DIN EN 1992-1-1, Equation (6.9) or

(6.14)sw link tension analogous to DIN EN 1992-1-1, Equation (6.8) or (6.13)

(RV 11) If the limit in accordance with (RV 10) is exceeded, the resistance to tension of the CFRP plate shall be ensured using bonded links. The shear force of the bonded links shall be designed according to Equation Error: Reference source not found and executed according to Error: Reference source not found. If the bonded links are not needed for the shear resistance of the component, they may be designed in accordance with RV 9.2.7.1, Case 2 according to Error: Reference source not found. If the bonded links are also needed for the shear resistance of the component, they shall be designed in accordance with RV 9.2.7.1, Case 1 according to Error: Reference source not found.

56


V LEd=max {EA L

EA L+EA s⋅V Ed

V Ed−V Rds (RV 6.107)Where:

EAL elastic stiffness of the bonded bending reinforcementEAs elastic stiffness of the embedded bending reinforcement

(RV 12) For all components with bending reinforcement in accordance with Error: Reference source not found, Error: Reference source not found and Error: Reference source not found where the limit value according to Equation Error: Reference source not found is exceeded, links in accordance with (RV 11) shall be executed.V Ed ≤0 . 33⋅f

ck2/3⋅bw⋅d(RV 6.108)

6.2.4 Shear between web and flange(RV 8) Shear reinforcement in accordance with 6.2.4(4) of DIN EN 1992-1-1 may be augmented by bonded reinforcement. For bonded reinforcement, only the force that can be anchored may be used as the resistance to tension.

6.2.5 Shear transfer in joints

RV 6.2.5.1 Design of the reprofiled joint(RV 1) For interfaces between concretes cast at different times in the bonded reinforcement area, an analysis of the shear transfer in the joint between concretes cast at different times, depending on location and size of the levelling area Error: Reference source not found, shall be conducted for the following areas.

(RV 2) The shear stress of the joint shall be obtained from the change in tensile force of the bonded reinforcement. The design longitudinal force component to be transferred by the joint shall be obtained under the assumption of even strain distribution and taking into account the magnitude of shift of tension envelope and prestrains of the reinforcing steel at the time of reinforcement.

(RV 3) The rules of DIN EN 1992-1-1, Section 6.2.5 shall apply to the analysis of shear at the interface between concretes cast at different times.

(RV 4) For bonded steel tabs, bonded CFRP plates and CF sheeting, an analysis of the reprofiled joint may be omitted if the value from the bond strength test in the adhesive pull test is used for bond stress L1. Adhesive pull tests shall be conducted in accordance with Part 4 of this Guideline.

Table RV 6.4: Analysis for levelling between or additions to concretes cast at different times

Column

1 2

Line Interface areas Analysis 1

Large-area Theoretical analysis of the bond between concretes cast at different times and adhesive pull test

2

Small-area

in the anchorage area of the plate to a distance of up to 1 500 mm from the plate end

3 Other areas Adhesive pull test for bond strength

RV 6.2.6 Shear reinforcement(RV 1) Curtailed or non-curtailed links (Error: Reference source not found), which are applied to the outside of the component by adhesive bonding, may be used for shear reinforcement.

57


nicht geschlossener Bügel non-curtailed link geschlossener Bügel curtailed link vollflächige Verklebung full-area bond verklebung in Streifen bond using strips

Figure RV 6.16: Schematic presentation of possible shear reinforcement types (RV 2) Non-curtailed links may only be used for shear reinforcement in rectangular cross-sections. For T-beams, links shall always be anchored in the compression zone.

(RV 3) If end links are necessary due to breakage in accordance with Section Error: Reference sourcenot found, they may be counted towards shear reinforcement.

(RV 4) In departure from DIN EN 1992-1-1 6.2.1, the shear resistance of the component with shear reinforcement may be obtained by means of Equation Error: Reference source not found.

V Rd=V Rd,s+V Rd,Lw+V ccd+V td (RV 6.109)(RV 5) For all loadbearing components, the strut angle shall be determined in accordance with DIN EN 1992-1-1 Section 6.2.3 in combination with the National Annex.

(RV 6) An analysis of the loadbearing capacity of struts in accordance with DIN EN 1992-1-1 Equation (6.9) shall also be furnished for shear reinforcement with the selected angle between struts.

(RV 7) For inclined links, the loadbearing capacity of the tension and compression struts may be calculated according to DIN EN 1992-1-1, Section 6.2.3(4).

(RV 8) Additional shear resistance may be obtained by means of Equation Error: Reference source not found. The compression strut angle may be determined in accordance with (RV5).

V Rd,Lw=ALw

sLw⋅z⋅f Lwd⋅cot θ

(RV 6.110)(RV 9) Depending on the application type, the sectional area of the shear reinforcement is calculated according to EquationError: Reference source not found. (Definitions see Error: Reference source not found)

ALw

sLw={2⋅tLw bLw

sLwVerklebung in Streifen

2⋅tLw Vollflächige Verklebung (RV 6.111)

58


(RV 10) The loadbearing capacity of the shear reinforcement fLwd shall be obtained by means of the following equations, depending on the material and reinforcement type:

- Curtailed link made of steel: Equation Error: Reference source not found- Curtailed link made of fibre composite material: Equation Error: Reference source not found- Non-curtailed link made of steel: Equation Error: Reference source not found- Non-curtailed link made of fibre composite material: Equation Error: Reference source not

found

Curtailed link made of steel (RV 11) The loadbearing capacity of a curtailed link made of steel is determined from the minimum of the yield point and the stress that can be transferred by lap joints.

f Lwd,GS=min {f yd ; f Gud,Lw } (RV 6.112)(RV 12) The stress that can be transferred by lap joints shall be obtained by means of Equations Error:Reference source not found through Error: Reference source not found as a function of plate thickness tL, modulus of elasticity EL and lap length l.

f Gud,LW=f Guk,Lw

γBG (RV 6.113)

f Guk,Lw={f Guk,Lw,max⋅lu,Lw

lu,Lw,max (2−lu,Lw

lu,Lw,max ) lu,Lw<l u,Lw,max

f Guk,Lw,ma x lu,Lw≥l u,Lw,max (RV 6.114)

f Guk,Lw,max=1 .004⋅√ ELw

tLw (RV 6.115)

lu,Lw,max=0. 121⋅√ELw⋅tLw (RV 6.116)Where:

ELw modulus of elasticity of the steel tab link in N/mm²tLw thickness of the steel tab link in mm

Curtailed link made of fibre composite material(RV 13) The loadbearing capacity of a curtailed link made of fibre composite material shall be obtained by means of Equation Error: Reference source not found.

f Lwd,GF=kR⋅αZeit⋅f Ld (RV 6.117)(RV 14) Here the reduction factor kR shall be obtained as a function of curve radius rc by means of Equation Error: Reference source not found.

k R={0 .5⋅rc

60 mm (2− rc

60 mm ) rc<60 mm

0,5 rc≥60 mm(RV 6.118)

(RV 15) The creep factor time is 0.75.

(RV 16) The construction rules in accordance with Section Error: Reference source not found on lap length and curves shall be taken into account.

Non-curtailed links(RV 17) The loadbearing capacity is determined by the minimum strength of the curtailed confinement and the bond strength, which is obtained as a function of the geometric relations Error: Reference source not found obtained by means of Equations Error: Reference source not found through Error: Reference source not found.

59


f Lwd=min { f bLwd ; f Lwd,G } (RV 6.119)

Anzahl Bügel: Number of links

Figure RV 6.17: Schematic presentation of the geometric situation of non-curtailed links

For d≥ lbL,max and lbL,max≤sLw≤d => f bLwd=

f bLk,max

γBA (RV 6.120)

For d≥ lbL,max and sLw≤lbL,max => f bLwd=

f bLk,max

γBA⋅((1− (m Lw−1 )

(n Lw−1 ) )+m Lw⋅(m Lw−1)⋅sLw

2⋅(n Lw−1 )⋅l bL,max ) (RV 6.121)

For d≤ lbL,max and sLw≤d => f bLwd=

f bLk,max

γBA⋅

nLw⋅sLw

2⋅lbL,max (RV 6.122)Where:

nLw integer quotient d /sLw

mLw integer quotient lbLmax/sLw

d effective static depth sLw spacing of bonded linksfbLk,max bond strength in accordance with Section Error: Reference source not foundlbL,max effective bond length in accordance with Section Error: Reference source not found

(RV 18) For sLW ≥ d, the location of the inner links shall be determined and the outer links placed so that exactly one bonded link will be placed between two inner links. The loadbearing capacity shall be obtained by means of equation as a function of component height by means of Equations Error: Reference source not found to Error: Reference source not found.

(RV 19) Bond strengths fbLk,max and effective bond lengths lbL,max may be determined in accordance with Error: Reference source not found.

(RV 20) The construction rules in accordance with Section Error: Reference source not found on lap length and curves shall be taken into account.

RV 6.2.7 End links to prevent breakage due to shift (RV 1) If the concentrated shear force at the end support or deep beam end is greater than the resistance shear force in accordance with Equation Error: Reference source not found, links at the plate end on the end support or deep beam end shall be provided in accordance with Section Error: Reference source not found.

60


V Rd,c,LE=0 . 75⋅(1+19.6⋅(100 ρ s1)0 ,15

aL0 ,36 )⋅V Rd,c

(RV 6.123)Where:

VRd,c in accordance with DIN EN 1992-1-1, Section 6.2.2 in combination with the National Annex and Section 6.2.2 of this Guideline

s1 longitudinal bond of internal reinforcing steel reinforcement (in accordance with DIN EN 1992-1-1, Section 6.2.2)

aL distance of plate from end support or deep beam end in mm

6.3 Torsion


6.3.2 AnalysisNo additions or amendments

6.3.3 Warping torsionNo additions or amendments

6.4 Punching shear


6.4.2 Loaded areas and critical sections used in analysesNo additions or amendments

6.4.3 AnalysisNo additions or amendments

6.4.4 Punching shear resistance of slabs and column bases without shear reinforcement (RV 3) When determining the punching shear resistance vRd,C in accordance with DIN EN 1992-1-1, Section 6.4.4, the bonded reinforcement must not be allocated to the tension reinforcement area Asl.

6.4.5 Punching shear resistance of slabs and column bases with shear reinforcementNo additions or amendments

6.5 Design with strut and tie models


6.5.2 StrutsNo additions or amendments

6.5.3 Ties(RV 4) Only the force to be anchored may be used as the tie force in bonded reinforcement.

6.5.4 Design of nodesNo additions or amendments

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6.6 Anchorages and laps(RV 4) The bonded reinforcement is considered sufficiently anchored if an analysis in accordance with Section RV 6.1.1 for bonded CFRP plates or CF sheeting, an analysis in accordance with Section RV 6.1.2 for bonded steel tabs and in accordance with Section RV 6.1.3 for CFRP plates bonded in indent cuts has been conducted to satisfaction.

(RV 5) The laps of bonded reinforcement shall be treated in accordance with RV 8.7.6.

6.7 Partial area loadingNo additions or amendments

6.8 Fatigue analysis

6.8.1 General(RV 3) A fatigue analysis under predominately non-static action shall be conducted for the adhesive bond. For bonded CFRP plates, this analysis shall be conducted in accordance with Section Error: Reference source not found, for bonded steel tabs in accordance with Section Error: Reference sourcenot found and for CFRP plates bonded in indent cuts in accordance with Section Error: Reference source not found. Steel tabs may be used for shear reinforcement, provided they are mechanically anchored in the compression zone. An analysis in accordance with the respective rules and regulations shall be conducted for the mechanical anchorage and the steel parts.

(RV 4) In addition to the fatigue analysis for the bonded reinforcement, a fatigue analysis in accordance with DIN EN 1992-1-1, Section 6.8 shall be conducted for the concrete, reinforcing steel and the prestressing steel. Fatigue analysis for reinforcing steel and prestressing steel in accordance with DIN EN 1992-1-1, Section 6.8 only applies to reinforcing steels and prestressing steels in accordance with DIN EN 1992-1-1, Sections 3.2 and 3.3. Additional tests will be required for other/older reinforcing steels and prestressing steels that already exist in the component to be reinforced.

6.8.2 Internal forces and stresses for fatigue verificationNo additions or amendments

6.8.3 Combination of actionsNo additions or amendments

6.8.4 Verification procedure for reinforcing and prestressing steelNo additions or amendments

6.8.5 Verification using damage equivalent stress range No additions or amendments

6.8.6 Other verificationsNo additions or amendments

6.8.7 Verification of concrete under compression or shearNo additions or amendments

RV 6.8.8 CFRP plates bonded to a surface(RV 1) The CFRP plate forces under predominately non-static action shall be determined at each intermediate crack element and at the anchorage. A fatigue analysis shall be conducted at the respective intermediate crack element and at the anchorage. An analysis of the plate force difference to be anchored shall be conducted in accordance with Section Error: Reference source not found. If this analysis cannot be conducted, the stress amplitude of the plate force to be anchored shall be furnished in accordance with Section Error: Reference source not found. The plate forces may be obtained assuming a uniform strain state.

62


RV 6.8.8.1 Analysis of plate force difference(RV 1) An analysis of stress amplitude observance may be omitted if it can be demonstrated that the elastic zone according to the law of bond stress-shift will not be exceeded under a combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3. For this, the following condition shall be satisfied:

FLRd,fat1 = 0.348 fctm,surf1/4 FLRd [kN] ≥ FLE,equ [kN] (RV 6.124)

Where:fctm,surf tensile strength of surface in N/mm²FLRd design resistance to change in plate force in kNFLE,equ plate force difference FL in accordance with Equation Error: Reference source not

found at the respective intermediate crack element under a combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3(3) in kN, or plate force under a combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3 (3) at the anchorage at the bending crack closest to the point of zero moment, taking the magnitude of shift of tension envelope in kN into account

(RV 2) The design resistance to change in plate force FLRd shall be obtained by means of Equation Error: Reference source not found.

ΔF LRd=ΔF Lk,BL

γBA (RV 6.125)Where:

FLk,BL base bond strength at the intermediate crack element in accordance with Equation Error: Reference source not found

BA bond safety factor, bonded on a surface

RV 6.8.8.2 Stress amplitude analysis at the crack edge subject to the higher load(RV 1) If the condition in accordance with Error: Reference source not found cannot be satisfied, the following analysis under combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3 shall be conducted:

ΔF LRd,fat2≥ΔF LEd,fat (RV 6.126)(RV 2) The stress amplitude resistance analysis at the crack edge FLRd,fat2 subject to the higher load shall be obtained as follows.

ΔF LRd,fat2=α⋅ΔF LRd (RV 6.127)

Where:

FLRd design resistance to change in plate force in accordance with Equation Error: Reference source not found, where for the plate force at the crack edge subject to the lesser load, the top load FLEd

O shall be used.

Reduction to determine FLRd,fat2: = -c · FLEd

U / FLRd + c (see Error: Reference source not found)

c

factor taking into account the stress cycles

c=0 ,342⋅NN¿−

1k

N stress cycles of the action

N* reference value of stress cycles N* = 2 · 106

k exponent for determining factor ck = k1 = 23.2 for N < N*k = k2 = 45.4 for N ≥ N*

63


(RV 3) The design stress amplitude from plate forces at the crack edge FLEd,fat subject to the higher load shall be obtained as follows:

ΔF LEd,fat=ΔFLEdO−ΔF

LEdU (RV 6.128)

Where:FLEd

O plate force difference FL under top load and cyclic action in accordance with DIN EN 1992-1-1, Section 6.8.3(3) at the relevant intermediate crack element or plate force under cyclic action in accordance with DIN EN 1992-1-1, Section 6.8.3(3) at the anchorage at the bending crack closest to the point of zero moment, taking the magnitude of shift of tension envelope in kN into account

FLEdU plate force difference FL under bottom load and non-cyclic action in accordance

with DIN EN 1992-1-1, Section 6.8.3(2) at the relevant intermediate crack element or plate force under non-cyclic action in accordance with DIN EN 1992-1-1, Section 6.8.3(2) at the anchorage at the bending crack closest to the point of zero moment, taking the magnitude of shift of tension envelope in kN into account

bezogene Unterlast Referenced bottom loadBeiwert Factor

Figure RV 6.18: Diagram for determining the reduction factor

64


Grenzlinie der Ünterlast Bottom load limit bezogene Schwingbreite Reference stress amplitudeGrenze des elastischen Bereichs Elastic zone limit

Figure RV 6.19: Goodman-Smith diagram to show fatigue analysis

RV 6.8.9 Bonded steel tabs (RV 1) In addition to a bond analysis, Error: Reference source not found a fatigue analysis for the steel tab shall be conducted in accordance with DIN EN 1993-1-9.

(RV 2) Forces in the steel tab under predominately non-static action shall be obtained at the bending crack closest to the point of zero moment, taking into account the magnitude of shift of tension envelope. At this point, the elastic zone in the law of bond stress-shift must not be exceeded under a combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3(3). For this, the following condition shall be satisfied:

FbLRd,fat1 = 0.348 fctm,surf1/4 fLbRd (lLb) bL tL ≥ FLE,equ (RV 6.129)

Where:fctm,surf tensile strength of surface in N/mm²fLbRd(lLb) design bond strength in accordance with Section Error: Reference source not

found in N/mm²FLE,equ plate force at the bending crack closest to the point of zero moment, taking into

account the magnitude of shift of tension envelope in kN under a combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.3(3)

RV 6.8.10 CFRP plates bonded in indent cuts (RV 1) With up to 2·106 stress cycles, sufficient resistance to fatigue of CFRP plates bonded in indent cuts may be assumed if, under frequent cyclical action in accordance with DIN EN 1992-1-1, Section 6.8.3(3), the anchorage force taking into account the magnitude of shift of tension envelope does not exceed value 0.6 FbLRd (FbLRd obtained by means of Equations Error: Reference source not found and Error: Reference source not found) and the plate stress amplitude does not exceed a value obtained by means of Equation Error: Reference source not found.

Δσ L≤500 N/mm²

tL [N/mm²]

(RV 6.130)

65


Where:tL plate thickness in mm

(RV 2) In a simplified approach to Paragraph (1), the analysis may be conducted using a frequent combination of actions in accordance with DIN EN 1992-1-1, Section 6.8.6. If this analysis can be conducted, no further tests will be necessary.

(RV 3) Design methods for stress cycles greater than 2·106 are not covered in this Guideline.

7 Serviceability limit states (SLS)

7.1 General(RV 4) For the purpose of serviceability limit state analysis, the stress-strain relations of the CFRP plates may be assumed to be linear. The analysis shall be conducted on the basis of the mean modulus of elasticity.

7.2 Limitation of stressesConcrete, reinforcing steel and prestressing steel (RV 8) The stress limits in accordance with DIN EN 1992-1-1 in combination with DIN EN 1992-1-1/NA shall apply.

(RV 9) Under infrequent combination of actions in the reinforced cross-section, the strain in the reinforcing steel may be limited to

ε s≤f yk

E s (RV 7.131).

Bonded CFRP plates and CFRP sheeting(RV 10) Under infrequent combination of actions in the reinforced cross-section, strain in the CFRP plate shall be limited to

ε L≤0 .2 % (RV 7.132).

(RV 11) If these strains are exceeded, an analysis of the component deformation, limitation of crack width and a detailed analysis of the bond serviceability limit state shall be conducted. Zone-wise decoupling of the plate shall be avoided for the analysis of bond serviceability limit state.

CFRP plates bonded in indent cuts (RV 12) Under infrequent combination of actions in the reinforced cross-section, strain in the CFRP plate shall be limited to

ε L≤0 .2 % (RV 7.133).

(RV 13) If these strains are exceeded, an analysis of the component deformation and limitation of crack width shall be conducted.

Bonded steel tabs (RV 14) Under infrequent combination of actions, strain in the reinforced cross-section of the steel tab shall be limited to

σ s≤0 . 8 f yk (RV 7.134). Column reinforcement by confinement(RV 15) To prevent damage to the concrete structure in the serviceability limit state, the theoretically required thickness of the confinement reinforcement tL, which is obtained from the sheeting thickness multiplied with the number of layers, shall satisfy the following condition:

66


tL≤D

2⋅EL⋅ε juk⋅ 1[k1 ]⋅[γ LG⋅[γ F⋅( [k 8]−[k9 ]⋅f ck)⋅(α cc⋅f ck+

A s

Ac⋅|εc2|⋅E s)− f syk

γs⋅

A s

Ac ]−f ck ](RV 7

.135)Where:

tL plate thickness in mmD cross-sectional diameter of the compression member in mmEL modulus of elasticity of the bonded reinforcement in N/mm²juk characteristic strain of the confining reinforcement in accordance with Error:

Reference source not foundLG safety factor for CF sheetingF weighted safety factor for actions according to contribution of constant and variable

action on the relevant structures in the ultimate limit state [k8] system coefficient (Annex K)[k9] system coefficient (Annex K)fck characteristic compressive strength of the concrete cc reduction factor for confined concrete compressive strength in the structure

cc = 0.85As cross-section of the reinforcing steel longitudinal reinforcement Ac concrete cross-section I*

c2I permissible concrete compression, to be determined for *c2 in accordance with DIN

EN 1992-1-1, Table 3.1. Taking into account the favourable effect of concrete creep at low eccentricities in accordance with DIN EN 1992-1-1/NA (NCI) re 6.1 (3)P is permissible.

Es modulus of elasticity of the reinforcing steel longitudinal reinforcement fsyk characteristic yield strain in the reinforcing steel longitudinal reinforcement

7.3 Crack control

7.3.1 General(RV 11) An analysis of crack width limitation can usually be omitted. If the crack width-limiting effect of bonded plates is to be used, the crack width may be obtained by means of Equation Error: Reference source not found if the crack pattern is complete.

7.3.2 Minimum reinforcement for limitation of crack widthNo additions or amendments

7.3.3 Control of cracking without detailed analysisNo additions or amendments

7.3.4 Calculation of crack width

RV 7.3.5 Crack width-limiting effect of bonded plates

RV 7.3.5.1 General(RV 1) Crack width limitation in existing structures requires that existing cracks are pressed or closed through seasonal forced loads. wk=scr,max⋅( εLm−εcm) (RV 7.136)(RV 2) The crack width is determined by twice the slip of the reinforcement. wk=2⋅ssr=2⋅sLr (RV 7.137)

67


(RV 3) Means plate strain shall be obtained by means of Equation Error: Reference source not found and the mean concrete strain may be obtained by means of Equation Error: Reference source not found or, in a simplified approach, it can be assumed to be zero.

ε Lm=ε LII⋅ηL−0,5⋅f ct,eff⋅Act,eff⋅( ξL

2

E s A s+EL AL⋅ξL2 )

(RV 7.138)

ε cm=0,4⋅f ct,eff

Ec (RV 7.139)Where:

Act,eff (sectional) area of zone of concrete section in which reinforcement is effective Act,eff is the concrete area around the tension reinforcement with height hc,ef, where hc,ef is the minimum of [2.5(h – ds); (h – x)/3; h/2] (see DIN EN 1992-1-1, Figure 7.1)

L ratio of bond strength of the bonded reinforcement to embedded reinforcement in accordance with Equation Error: Reference source not found

fct,eff mean effective tensile strength of the concrete that can be expected when cracking occurs (see also DIN EN 1992-1-1, Section 7.3.2)

LII strain of the plate in the crack using Bernoulli’s theory on beams assumptions L factor taking into account the different elastic stiffness values and bond strengths in

accordance with Equation Error: Reference source not found; without reinforcing steel reinforcement, this factor is 1.0.

(RV 4) The maximum crack spacing scr,max may be obtained by means of Equation Error: Reference source not found. The mean bond stress Lm of the bonded reinforcement may be determined in accordance with Section RV 7.3.5.2 or RV 7.3.5.3, depending on the reinforcement type.

scr,max=Ac,eff⋅f ct,eff

2⋅τLm⋅

kLb⋅EL⋅tL⋅ξ L2

Es As+EL AL⋅ξL2

(RV 7.140)(RV 5) The ratio of bond strength of the bonded reinforcement to embedded reinforcement may be obtained by means of Equation Error: Reference source not found as a function of mean bond stresses according to Equation Error: Reference source not found and Section RV 7.3.5.2 or RV 7.3.5.3. Factor L for taking into account the different elastic stiffnesses and bond strengths may be obtained by means of Equation Error: Reference source not found using factor L obtained by Equation Error: Reference source not found.

ξ L=√ τLm

τ sm⋅

Es⋅ds

kLb⋅EL⋅t L (RV 7.141)

δL=εLr

εsr=

2⋅ξL2

ξL2+1 (RV 7.142)

ηL=(1+EL AL/ (Es A s ))⋅δL

1+EL AL/ (Es A s )⋅δL (RV 7.143)(RV 6) The mean bond stresses of reinforcement embedded in concrete may be obtained by means of Equations Error: Reference source not found. In Equation Error: Reference source not found factor s shall be obtained from Error: Reference source not found. Factor kseff in Equation Error: Reference source not found shall be obtained by means of value ks from Error: Reference source not found and factor kt according to Equation Error: Reference source not found taking into account bond creep obtained by means of Equation Error: Reference source not found.

τ sm=ks,eff√ f cm

α s+1⋅ssr

αs

[N/mm²] (RV 7.144)

68


k s,eff=1

(1+k t )αs

ks

(RV 7.145)

k t=(1+10⋅t )0 . 08−1 (RV 7.146)Where:

t residual life span in hours

fcm mean cylinder compressive strength in N/mm²

ssr slip of reinforcing steel in accordance with Equation Error: Reference source not found

Table RV 7.5: Bond factors of embedded reinforcement for calculation of crack width

Column

1 2 3

Line Ribbed bars Smooth bars 1 Bond conditions Good Medium Good Medium2 s 0.25 0.25 0 03 ks 2 1 0.25 0.13

RV 7.3.5.2 CFRP plates bonded in indent cuts (RV 1) The mean bond stresses of CFRP plates bonded in indent cuts may be obtained by means of Equation Error: Reference source not found. In Equation Error: Reference source not found the factor L shall be obtained by means of Equation Error: Reference source not found from one-sided adhesive thickness tG. Factor kLeff in Equation Error: Reference source not found shall be obtained by means of Equations Error: Reference source not found to Error: Reference source not found

τ Lm=kL,eff

α L+1⋅sLr

α L⋅(1−α L)(RV 7.147)

α L=0 .38⋅tG−0 .11≤0 . 31 (RV 7.148)

k L,eff=1

(1+kt )α L

k L

(RV 7.149)

k L=5α L⋅τbGk (RV 7.150)

k t=(1+10⋅t )0 . 14−1 (RV 7.151)k Lb=2 (RV 7.152)Where:

t residual life span in hoursbGk characteristic bond strength at adhesive failure according to Equation Error:

Reference source not found in N/mm²tG adhesive thickness in mmsLr plate slip obtained by means of Equation Error: Reference source not found

(RV 2) For the crack width-limiting effect of plates bonded in indent cuts, the plate spacing must not exceed 200 mm.

RV 7.3.5.3 Adhesive bonding (RV 1) The mean bond stresses are assumed to be constant for adhesive bonding and shall be obtained by means of Equation Error: Reference source not found. The marginal values sL0k andL1k

were taken from Annex RV K or are regulated by general building inspectorate approvals.

69


τ Lm={τL1k

2⋅sL1k⋅sLr für 0≤sLr≤sL1k

τL1k⋅(sLr2−2⋅sLr⋅sL0k+sL1k⋅sL0k )2⋅sLr⋅(sL1k−sL0k )

für sL1k≤sLr≤sL0k

(RV 7.153)

sL1k=2,5⋅50 mmEcm

⋅τ L1k(RV 7.154)

k Lb=4 (RV 7.155)Where:

sLr plate slip obtained by means of Equation Error: Reference source not found(RV 2) For the crack width-limiting effect of the bonded CFRP plates, centre distance aL shall not exceed the specifications in RV 8.2.1.1. Likewise, centre distance aL 3∙bL shall be observed.

(RV 3) To apply the crack width-limiting effect of adhesive bonding, the condition of Equation (RV 7.26) must be satisfied.

Es⋅φs

EL⋅tL≤32

(RV 7.156)

7.4 Limitation of deformations

7.4.1 General(RV 7) The limit values for deformations in accordance with DIN EN 1992-1-1, Section 7.4.1 shall be observed even after the reinforcement measures.

(RV 8) The deformations may be calculated in accordance with DIN EN 1992-1-1, Section 7.4.3. As a rule, deformation analysis without direct calculation in accordance with DIN EN 1992-1-1, Section 7.4.2 must not be used for reinforced components.

7.4.2 Cases where calculations may be omitted(RV 8) As a rule, deformation analysis without direct calculation in accordance with DIN EN 1992-1-1, Section 7.4.2 must not be used for reinforced components.

7.4.3 Checking deflections by calculation(RV 9) In calculating the deflections in accordance with DIN EN 1992-1-1, Section 7.4.3, the effect of the plate may be taken into account in the deflection parameters .

(RV 10) Deflections at the time of reinforcement shall also be taken into account.

8 Detailing of reinforcement and prestressing tendons — general

8.1 General(RV 5) The general reinforcement rules in accordance with DIN EN 1992-1-1 in combination with DIN EN 1992-1-1/NA shall apply, unless stipulated otherwise.

8.2 Spacing of reinforcing steel bars

RV 8.2.1 Spacing of plates

RV 8.2.1.1 Bending reinforcement using steel tabs, CFRP plates and CF sheeting bonded to a surface (RV 1) The following applies to the centre distance aL of tension plates:

70


max aL 0.2 times effective span 5 x T-beam thickness 0.4 x cantilever length

(RV 2) The edge distance of the plate’s longitudinal edge shall be at least equivalent to the nominal concrete cover cnom of the embedded reinforcement.

RV 8.2.1.2 Bending reinforcement using CFRP plates bonded in indent cuts

RV 8.2.1.2.1 Edge distances (RV 1) A minimum distance ar to the free component shall be maintained, which shall be equivalent to the greater of Equations Error: Reference source not found and Error: Reference source not found.

ar 2∙bL

(RV 8.157)ar dg

(RV 8.158)Where:

bL CFRP plate width dg maximum particle size

(RV 2) To arrange CFRP plates on both sides of a free edge in accordance with Error: Reference source not found, a minimum distance from one of the plates in accordance with Equation Error: Reference source not found shall be maintained.

ar 4∙bL

(RV 8.159)

Figure RV 8.20: Edge distances in arrangement of plate on both sides of an edge (RV 3) For plates and beams that are not equipped with tab links for absorbing deflection forces in the curvature zone of the CFRP plates, a minimum edge distance of 150 mm in the direction of centre of curvature shall be maintained. For other cases, Sections (RV1) and (RV2) shall apply. The curvature radius of bonded plates shall be at least 2 m.

RV 8.2.1.2.2 Centre distance(RV 1) To following applies to the minimum centre distance aL of tension plates:

aL dg

(RV 8.160)for as > 2∙ the following applies: aL bL

(RV 8.161)Where:

diameter of the reinforcing steel bond running parallel to the CFRP plates as clear space between two bars of the reinforcement that is parallel to the CFRP

71


plates dg maximum particle size

(RV 2) For clear spaces in the reinforcing steel bond of less than 2ds, the minimum centre distance for tension plates according to Error: Reference source not found shall be maintained.

Achsabstand der CFK-Lamellen Centre distance of CFRP plates lichter Abstand der parallel zu den CFK-Lamellen verlaufenden Bewehrung

Clear space of that reinforcement that is parallel to the CFRP plates

Durchmesser der parallel zu den CFK-Lamellen verlaufenden Bewehrung

Diameter of reinforcement that is parallel to the CFRP plates

Figure RV 8.21: Minimum centre distance of tension plates (RV 3) The following applies to the maximum centre distance aL of tension plates:

aL 0.2 l0

(RV 8.162)aL 4 h

(RV 8.163)Where:

l0 effective span in mm, for cantilever arms: l0 = 2 lk

h component thickness in mm

8.3 Bending of steel

RV 8.3.1 Bending of the bonded reinforcement (RV 1) Steel tabs for link reinforcement may be pre-bent at the factory.

(RV 2) Recently manufactured CFRP plates may not planned to be arranged at a radius that is less than 1 000 times their thickness.

(RV 3) CF sheeting may be arranged bent, provided the curve radius of the concrete cover is at least 25 mm.

8.4 Anchorage of longitudinal reinforcement


8.4.2 Ultimate bond stressNo additions or amendments

72


8.4.3 Basic anchorage lengthNo additions or amendments

8.4.4 Design anchorage lengthNo additions or amendments

RV 8.4.5 Anchorage of the bonded reinforcement (RV 1) For anchorage of CFRP plates bonded in indent cuts, the analysis in accordance with Section Error: Reference source not found shall be conducted.

(RV 2) For anchorage of bonded CFRP plates and CF sheeting, bending reinforcement analysis in accordance with Section Error: Reference source not found shall be observed. For bonded links, Section Error: Reference source not found and Error: Reference source not found should be observed.

(RV 3) For anchorage of bonded steel tabs, bending reinforcement analysis in accordance with Section Error: Reference source not found shall be observed. For bonded links, Sections Error: Reference source not found and Error: Reference source not found should be observed.

RV 8.4.6 Base dimension of the adhesive bond for reinforcement bonded to a surface (RV 1) The bond of adhesive reinforcement is described by the differential equation of the shifting bond. For the bond stress-slip relations, a bilinear bond method is used for flat elements, described by three parameters sL0k, L1k and LRk. The parameters can be found in Annex RV K or may be regulated by general building inspectorate approvals.

(RV 2) The maximum resistance to plate tension at the individual crack shall be obtained by means of Equation Error: Reference source not found.

f bLk,max=√ ELm⋅sL0k⋅τL1k

tL (RV 8.164)

f bLk ( lbL )={f bLk,max⋅lbL

lbL,max (2−l bL

lbL,max ) lbL<lbL,max

f bLk,max l bL≥lbL,max (RV 8.165)

f bLd ( lbL)=f bLk( lbL)

γBA (RV 8.166)(RV 3) The corresponding maximum effective bond length of the adhesive bond can be obtained by means of Equation Error: Reference source not found where Lb = 1.128.

lbL,max=2

κLb⋅√ ELm⋅t L⋅sL0k

τL1k (RV 8.167)

RV 8.4.7 Base dimension of the adhesive bond in indent cuts (RV 1) The bond strength of adhesive bond in indent cuts can be obtained by means of Equation Error: Reference source not found from the minimum bond strength of concrete and adhesive.

τ bLd=1

γ BE⋅min {τbGk⋅αbG

τ bck⋅αbc (RV 8.168)Bond stress of the adhesive according to Equation Error: Reference source not found

τ bGk=ksys⋅√(2⋅f Gtk−2⋅√( f Gtk2 + f Gck⋅f Gtk )+ f Gck )⋅f Gtk (RV 8.169)

and bond stress of the concrete according to Equation Error: Reference source not found.

73


τ bck=kbck⋅√ f cm (RV 8.170)Where:

fcm mean cylinder compressive strength of the concrete in N/mm² ksys product-specific system factor for adhesive bond failure in accordance with general

building inspectorate approvals [-]ksys = 0.6 may be used for predimensioning

kbck product-specific system factor for concrete bond failure in accordance with general building inspectorate approvals [-] kbck = 4.5 may be used for predimensioning

bG product-specific system factor for endurance behaviour of adhesive bond in accordance with general building inspectorate approvals [-]bG = 0.5 may be used for predimensioning.

bC product-specific system factor for endurance behaviour of concrete in accordance with general building inspectorate approvals [-]bc = 0.9 may be used for predimensioning.

8.5 Anchorage of links and shear reinforcementNo additions or amendments

8.6 Anchorage by welded barsNo additions or amendments

8.7 Laps and mechanical couplers


8.7.2 Laps No additions or amendments

8.7.3 Lap lengthNo additions or amendments

8.7.4 Transverse reinforcement in the lap zoneNo additions or amendments

8.7.4.1 Transverse reinforcement for bars in tension No additions or amendments

8.7.4.2 Transverse reinforcement for bars permanently in compression No additions or amendments

8.7.5 Laps for welded mesh fabrics made with ribbed wiresNo additions or amendments

8.7.5.1 Laps of the main reinforcement No additions or amendments

8.7.5.2 Laps of secondary or distribution reinforcement No additions or amendments

74


RV 8.7.6 Plate lap joints

RV 8.7.6.1 Bonded CFRP plates (RV 1) Bonded plates may be joined by lapping if the lap joint is in an area where the existing plate tensile strength does not exceed the maximum force transferable in the lap joint in accordance with Equation Error: Reference source not found. The joint between plates may be executed as a lap joint bonded by adhesive. The lap length may be obtained by means of Equation Error: Reference source not found.

Füd,max=0 , 753

γ BG⋅bL⋅√ELm⋅tL

(RV 8.171)

lü,max=0 ,161⋅√ELm⋅tL (RV 8.172)

(RV 2) Bonded plate joints are not permissible for predominately non-static action.

RV 8.7.6.2 CF sheeting bonded to a surface (RV 1) Bonded CF sheeting may only be joined by lap under the following conditions: The lap joint shall be in an area where the existing sheeting tensile strength does not exceed 60 % of the limit tensile strength of the sheeting.

(RV 2) The sheeting layers of joined sections shall overlap each other at 250 mm.

(RV 3) Bonded sheeting joints are not permissible for predominately non-static action.

RV 8.7.6.3 Bonded steel tabs (RV 1) Bonded steel tabs may be joined by lapping if the lap joint is in an area where the existing plate tensile strength does not exceed the maximum force transferable in the lap joint in accordance with Equation Error: Reference source not found. The connection between the tab and the overlap panel of the same thickness tL shall be executed by fillet welds designed in accordance with DIN EN 1993-1-8 prior to adhesive bonding of the tab and arranged on the side of increasing tensile force. On the side of decreasing tensile force, the lap panel may be bonded onto the tab. The lap length may be obtained by means of Equation Error: Reference source not found.

Füd,max=1. 004

γBG⋅bL⋅√ELm⋅tL

(RV 8.173)

lü,max=0. 121⋅√ELm⋅tL (RV 8.174)(RV 2) Bonded plate joints are not permissible for predominately non-static action.

8.8 Additional rules for large diameter barsNo additions or amendments

8.9 Bundled bars


8.9.2 Anchorage of bundles of barsNo additions or amendments

8.9.3 Lapping bundles of barsNo additions or amendments

75


8.10 Prestressing tendons

8.10.1 Arrangement of prestressing tendons and ductsNo additions or amendments


8.10.1.2 Pre-tensioned membersNo additions or amendments

8.10.1.3 Post-tension ducts No additions or amendments

8.10.2 Anchorage of pre-tensioned tendonsNo additions or amendments


8.10.2.2 Transfer of prestressNo additions or amendments

8.10.2.3 Anchorage of tendons for the ultimate limit statesNo additions or amendments

8.10.3 Anchorage zones of post-tensioned or unbonded membersNo additions or amendments

8.10.4 Anchorages and couplers for prestressing tendonsNo additions or amendments

8.10.5 DeviatorsNo additions or amendments

9 Detailing arrangements for structural members

9.1 GeneralNo additions or amendments

9.2 Beams

9.2.1 Longitudinal reinforcementNo additions or amendments

9.2.1.1 Maximum and minimum reinforcement areas No additions or amendments

9.2.1.2 Other detailing arrangementsNo additions or amendments

9.2.1.3 Curtailment of longitudinal tension reinforcement (RV 5) The offset tensile force and resistance to tension curves for the ultimate limit state shall be shown for each component. Cutting into the offset tensile strength curve is not permissible.

76


9.2.1.4 Anchorage of bottom reinforcement at an end supportNo additions or amendments

9.2.1.5 Anchorage of bottom reinforcement at intermediate supports No additions or amendments

9.2.2 Shear reinforcement(RV 9) Bonding by adhesive as shear reinforcement is not permissible.

9.2.3 Torsion reinforcementNo additions or amendments

9.2.4 Surface reinforcementNo additions or amendments

9.2.5 Indirect supportsNo additions or amendments

RV 9.2.6 Links of the bonded reinforcement (RV 1) The anchorage zone of the bending reinforcement shall be curtailed with a tab link made of steel or bonded sheeting if an analysis in accordance with Section Error: Reference source not found cannot be carried out. The link must not be located more than 50 mm from the plate end (Error: Reference source not found).

Endverbügelung End link Biegeverstärkung Bending reinforcement

Figure RV 9.22: Arrangement of the tab link or CF sheeting at the plate end (RV 2) The tab link in accordance with Section (RV1) shall be designed for the design concentrated tensile force in accordance with Equation Error: Reference source not found.

FLwEd=FLEd¿ ⋅tan θ (RV 9.175)

(RV 3) For bonded CFRP plates, CF sheeting and steel tabs, FLd* is equivalent to the maximum bond

force in accordance with Equation Error: Reference source not found.

FLEd¿ = f bLk,max⋅bL⋅t L (RV 9.176)

(RV 4) In CFRP plates bonded in indent cuts, FLd* is equivalent to the design tensile strength of the

anchored CFRP plates at their end, which is to be calculated under the assumption of even strain distribution and a rigid bond as well as taking into account of the magnitude of shift of tension envelope.

(RV 5) In Equation Error: Reference source not found, corresponds to the angle underlying the shear force analysis in accordance with Section Error: Reference source not foundor Error: Reference source not found.

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(RV 6) The link anchorage may be executed by adhesive bonding or anchorage in the compressive zone. The tab link to be arranged in the anchorage zone may be attributed to the steel tabs absorbing the shear force, provided it is in accordance with Section Error: Reference source not found.

(RV 7) Anchorage of links in the compression zone may be foregone if the tensile force allocated to the link can be transmitted to the concrete component via adhesive bond. Analysis in accordance with Equation Error: Reference source not found.

FLwEd≤2⋅FbLwRd (RV 9.177)

(RV 8) The bond break-off force per link leg FbLwRd shall be calculated by means of Equation Error: Reference source not found. The links shall be bonded by adhesive over the entire web height. Only half of the existing adhesive bonding length may be used as bond length lbL. Bond strength fbLd(lbL) shall be determined in accordance with Section RV 8.4.6.

FbLwRd=bLw⋅tLw⋅f bLd ( lbL ) (RV 9.178)(RV 9) If links in accordance with Section 6.2.3 (RV 10), (RV 11) and (RV 12) are required that are not needed for the shear resistance of the component, anchorage in the compression zone can be foregone. Links shall be designed in accordance with Equation Error: Reference source not found.

V LEd≤2⋅FbLwRd

sLw⋅z⋅cotθ

(RV 9.179)Where:

FbLwRd in accordance with Section (RV 8) and Equation Error: Reference source not foundcot compression strut incline of shear force design sLw spacing of bonded links z inner lever arm of component, may be assumed to be 0.9 · d

RV 9.2.7 Execution of bonded links

RV 9.2.7.1 General(RV 1) In general, one distinguishes between three cases of bonded links:

Case 1: The bonded link is needed for shear force design. The bonded link shall be designed in accordance with Section Error: Reference source not found. If tab links are executed as curtailed links in accordance with Section Error: Reference source not found, the centre distance of adjacent tab links must not be greater than the beam height. If tab links are executed as non-curtailed links in accordance with Section Error: Reference source not found, the centre distance of adjacent tab links must not be greater than half the beam height. Links according to case 1 may be used as end links in accordance with Section Error: Reference source not found. Additionally, with this link, an increase in bond strength in accordance with Section Error: Reference source not found may be assumed. Here, the effects from shear force according to Section Error: Reference source not found, the effects from linkage according to Section Error: Reference source not found and the effects from crack opening force Fu (b) according to Equation Error: Reference source not found shall be superposed.

Case 2: The bonded link is used as end link or is necessary due to linking in accordance with Section 6.2.3 (RV 10), (RV 11) and (RV 12). This link shall be designed and arranged in accordance with Section Error: Reference source not found. It is not necessary to anchor this link in the compression zone. Additionally, with this link, an increase in bond strength in accordance with Section Error: Reference source not found may be assumed. Here, the effects from shear force according to Section Error: Reference source not found shall be superposed with the effects from crack opening force Fu (b) according to Equation Error: Reference source not found.

Case 3: Due to an increase in bond strength, the bonded link is arranged in accordance with Section Error: Reference source not found. This link may be arranged free and shall be designed for crack opening force Fu (b) in accordance with Equation Error: Reference source not found. Anchorage may be executed in accordance with Section Error: Reference source not found (RV8) or additional anchorage elements in the compression zone.

78


RV 9.2.7.2 Steel tab links (RV 1) The tab links shall be arranged perpendicular to the component axis and bonded by adhesive over the entire web height. Here the centre distance must not exceed component height h.

(RV 2) If they are anchored in the compression zone, the tensile force to be anchored may be reduced to 2/3 of its calculated value for predominantly static actions.

(RV 3) For components that are not accessible from above, anchorage of the tab links in the compression zone may be executed using approved adhesive anchors.

(RV 4) With anchorage by adhesive bond, the tab links shall be protected against falling (e.g. by means of dowels) in case of fire.

(RV 5) Bonded tabs may be joined by lapping in accordance with Error: Reference source not found, if the existing tab force does not exceed the maximum force according to Equation Error: Reference source not found that can be transmitted in the lap joint. The lap length may be obtained by means of Equation Error: Reference source not found.

Füd,max=1. 004

γBG⋅bL⋅√ELm⋅tL

(RV 9.180)

lü,max=0.121⋅√ELm⋅tL (RV 9.181)(RV 6) In a lap joint in accordance with (RV5) or Error: Reference source not found, the leg length of the curtailment links ls,U shall be bw – 20 [mm]. The leg length of the curtailment angle ls,A shall equal (bw – bL)/2 + 20 [mm] if bond strength increase due to the link according to Section Error: Reference source not found is assumed. Otherwise the leg length of the curtailment angle shall equal ls,A = 0.5 lü,max.

(RV 7) Bonded tab joints are not permissible for predominately non-static action.

Figure RV 9.23: Construction of a bonded link lap joint

RV 9.2.7.3 CF sheeting(RV 1) The CF sheeting shall be laminated over the entire web with the fibres perpendicular to the component axis.

(RV 2) The layers may be joined individually using a lap length of 250 mm.

(RV 3) The centre distance of the shear CF sheeting must not exceed the component height h.

(RV 4) The corners of the webs shall be curved at a minimum r ≥ 25 mm.

9.3 Solid slabs

9.3.1 Flexural reinforcement

9.3.1.1 General(RV 6) The offset tensile force and resistance to tension curves for the ultimate limit state shall be shown for each component. Cutting into the offset tensile strength curve is not permissible.

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(RV 7) For slabs, shear reinforcement in accordance with DIN EN 1992-1-1, Section 9.3.1.1 must be in place. Missing shear reinforcement may be added using adhesive bonding reinforcement. For design purposes, the bond break force in accordance with Section Error: Reference source not found or Error:Reference source not found shall be used as the maximum plate force.

(RV 8) For one-way spanning slabs, 20 % of the existing steel reinforcement is also sufficient for the shear reinforcement of reinforced components.

(RV 9) For slabs with flexible support, at least half of the required field reinforcement should be routed through the support and anchored there in accordance with DIN EN 1992-1-1, Section 8.4.4. The magnitude of shift of tension envelope aL of the T-beams without shear reinforcement is assumed to be 1.0d. If less than 50 % of the required field reinforcement of reinforcement slabs is anchored in the support, the magnitude of shift of tension envelope shall be increased by factor 0.5(erf As,field/vorh As,support) ≥ 1.0. Regardless of this, in reinforced components, at least 25 % of As,field shall be routed through the support.

(RV 10) For the analysis of plate or steel tab anchorage in accordance with RV 6.1.1.4 and RV 6.1.2.3, magnitude of shift of tension envelope may be determined for 0.5 h in departure from DIN EN 1992-1-1, Section 9.3.1.1 (4). For anchorage of the longitudinal reinforcement, the magnitude of shift of tension envelope shall be selected in accordance with DIN EN 1992-1-1, Section 9.3.1.1 (4).

9.3.1.2 Reinforcement in slabs near supports No additions or amendments

9.3.1.3 Corner reinforcementNo additions or amendments

9.3.1.4 Reinforcement at the free edges No additions or amendments

9.3.2 Shear reinforcementNo additions or amendments

9.4 Flat slabs

9.4.1 Slab at internal columnsNo additions or amendments

9.4.2 Slab at edge columnsNo additions or amendments

9.4.3 Punching shear reinforcementNo additions or amendments

9.5 Columns

9.5.1 General

9.5.2 Longitudinal reinforcement

9.5.3 Shear reinforcement(RV 7) In non-reinforced columns with insufficient shear reinforcement in accordance with DIN EN 1992-1-1, Section 9.5.3, missing shear reinforcement may be added in the form of CF sheeting bonded by adhesive. It shall be bonded as a minimum of two wrapped layers. The necessary sheeting cross-section may be obtained by means of Equation Error: Reference source not found. Construction notes according to RV 9.5.4 shall be taken into consideration.

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AL,erf=A s,erf⋅f yd

0,9⋅f Lwd,GF (RV 9.182)Where:

As,erf required shear reinforcement in accordance with DIN EN 1992-1-1, Section 9.5.3 fyd design yield strength of the longitudinal reinforcement fLwd,GF design strength of the sheeting according to Equation Error: Reference source not

found

RV 9.5.4 Column reinforcement(RV 1) For column reinforcement in accordance with Section Error: Reference source not found, the columns shall be wrapped completely and over the entire column height in CF sheeting bonded by adhesive according to Error: Reference source not found.

Vollflächige Umschnürung über die gesamte Stützenhöhe

Complete confinement over the entire column height

Figure RV 9.24Arrangement of CF sheeting (RV2) The minimum lap length of CF sheeting is 250 mm.

(RV 3) The corners of rectangular columns shall be curved at a minimum r ≥ 25 mm.

9.6 Walls


9.6.2 Vertical reinforcementNo additions or amendments

9.6.3 Horizontal reinforcementNo additions or amendments

9.6.4 Shear reinforcementNo additions or amendments

9.7 Deep beamsNo additions or amendments

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9.8 Foundations

9.8.1 Pile capsNo additions or amendments

9.8.2 Column and wall footingsNo additions or amendments


9.8.2.2 Anchorage of barsNo additions or amendments

9.8.3 Tie beamsNo additions or amendments

9.8.4 Column footing on rockNo additions or amendments

9.8.5 Bored pilesNo additions or amendments

9.9 Regions with discontinuity in geometry or action (D regions) No additions or amendments

9.10 Limitation of damage due to accidental actions

9.10.1 General(RV 7) Steel tabs and links shall be protected against falling (e.g. by means of dowels) in case of fire.

9.10.2 Proportioning of tiesNo additions or amendments


9.10.2.2 Peripheral tiesNo additions or amendments

9.10.2.3 Internal tiesNo additions or amendments

9.10.2.4 Horizontal ties to columns and/or walls No additions or amendments

9.10.2.5 Vertical tiesNo additions or amendments

9.10.3 Continuity and anchorage of tiesNo additions or amendments

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10 Additional rules for precast concrete elements and structures

No additions or amendments

11 Lightweight aggregate concrete structuresNo additions or amendments

12 Plain and lightly reinforced concrete structuresNo additions or amendments

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DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding – Part 1: Design and construction

Annex RV K: Recommended system coefficients (informative)

RV K1 Values for reinforcements created by adhesive bonding:

L1k sL0k LFk

Steel tabs 0 .300⋅√α cc⋅f cm⋅α ct⋅f ctm,surf 0 . 185 mm 0

CFRP plates 0 . 366⋅√α cc⋅f cm⋅α ct⋅f ctm,surf 0 . 201 mm 10 . 8⋅α cc⋅f cm−0 ,89

Where:fctm,surf mean tensile strength of surface in N/mm² (according to Part 4) fcm mean cylinder compressive strength in N/mm² (according to Part 4) cc factor taking into account the long-term effects on compressive strength of

concrete. cc in accordance with DIN EN 1992-1-1 in combination with the National Annex

ct factor taking into account the long-term effects on axial tensile strength of concrete.ct in accordance with DIN EN 1992-1-1 in combination with the National Annex

RV K2 System coefficient for columns:

Recommendations for pre-design:

[k0] = 0.2 · 1/(N/mm²)[k1] = 2.0[k2] = 0.25[k3] = 0.7[k4] = 1.0 (building)[k5] = 1.0 (building)[k6] = 0.75[k7] = 0.39[k8] = 0.89[k9] = 0.44 · 10-2

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Annex RV L Determination of cross-section values (informative)

RV L1 Ultimate limit state

RV L1.1 General(RV 1) In the area of linear-elastic concrete behaviour and pure bending stress (NEd = 0), the line of zero strain is equivalent to the mechanical centroid of the cracked cross-section. For these conditions, the special cases of rectangular cross-section and T-beam cross-section have been solved in the following sections.

RV L1.2 Rectangular cross-sections(RV 1) For rectangular cross-sections, the compression zone may be obtained by means of Equation Error: Reference source not found. Without compression reinforcement, s2 can be set to zero.

x=[−(α L⋅ρL+αS⋅(ρS1+ ρS2))+√(αL⋅ρL+α S⋅( ρS1+ρS2 ))2+2⋅(αL⋅ρL⋅d L

h+αS⋅(ρS1⋅

dh+ρS2⋅

d2

h )) ]⋅h(RV L.183)

Where:

ρS1=AS1

b⋅hρS2=

AS2

b⋅hρL=

AL

b⋅h

α S=ES

ECα L=

EL

EC

(RV 2) By way of simplification, the inner lever arms may be obtained by means of Equation Error: Reference source not found or Error: Reference source not found

zs=d−ka⋅x≈d−0,4⋅x (RV L.184)

z L=h−ka⋅x≈h−0,4⋅x (RV L.185)

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RV L1.3 T-beams(RV 1) For T-beams where the compression zone is located in the beam only, Equation Error: Reference source not found where b = beff may be applied.

(RV 2) For T-beams where the compression zone is also located in the web, the compression zone may be obtained by means of Equation Error: Reference source not found and the corresponding values in accordance with Equations Error: Reference source not found and Error: Reference source not found.

x=(−A+√A2+B )⋅h (RV L.186)

A=h t

h⋅( beff

bw−1)+αS⋅(ρS1+ ρS2)+α L⋅ρL

(RV L.187)

B=2⋅( ht

h )2

⋅( beff

bw−1)+2⋅(α L⋅ρL⋅

dL

h+α S⋅( ρS1⋅

dh+ ρS2⋅

d2

h )) (RV L.188)(RV 3) By way of simplification, the inner lever arms may be obtained by means of Equation Error: Reference source not found orError: Reference source not found.

zs=d−ka⋅x≈d−0,4⋅x (RV L.189)

z L=h−ka⋅x≈h−0,4⋅x (RV L.190)

RV L2 In the ultimate limit state (RV 1) Using the equilibrium of internal and external forces according to Equations Error: Reference source not found and Error: Reference source not found, the strains and thus the forces and lever arms may be determined by iteration on the cracked cross-section. The necessary equations are given below.

(RV 2) The equilibrium of internal and external forces is obtained when action-effect equals resistance.

M Rd=MEd(RV L

.191)

(RV 3) The resistance of the cross-section to bending is calculated using reinforcement and its lever arm according to Equation Error: Reference source not found.M Rd=A s1⋅Es⋅εs1⋅( d−ka⋅x )+AL⋅EL⋅ε L⋅(d L−ka⋅x )+As2⋅Es⋅εs2⋅(ka⋅x−d2 )

(RV L.192)

(RV 4) The equilibrium of inner forces is described by Equation Error: Reference source not found. αR⋅f cd⋅b⋅x+A s2⋅E s⋅εs2=A s1⋅E s⋅εs 1+AL⋅EL⋅ε L

(RV L.193)

(RV 5) The strains of the reinforcements may be obtained using concrete compression on the

assumption of even distribution of strains.

ε s2=εc⋅d2−x

x≤

f yd

E s (RV L.194)

ε s1=εc⋅d−x

x−ε0≤

f yd

E s (RV L.195)

ε L=εc⋅dL−x

x−ε0≤ε Lud

(RV L.196)

86


(RV 6) The completeness coefficient and the factor for inner lever arm on the basis of the parabola rectangle diagram for concrete are determined as a function of concrete compression obtained by means of Equations Error: Reference source not found and Error: Reference source not found. Simplified determination of concrete compressive forces using a tension block in accordance with DIN EN 1992-1-1 is permissible.

α R=(1 000 εc⋅(0. 5−1 000

12⋅εc) for εc≤0 .002

1− 23 000⋅εc

for 0. 002≤εc≤0 .0035(RV L.197)

k a=(

8−1 000⋅ε c

4⋅(6−1 000⋅εc )for ε c≤0 . 002

1 000⋅ε c⋅(3 000⋅ε c−4 )+22 000⋅ε c⋅(3 000⋅ε c−2 )

for 0 . 002≤ε c≤0 . 0035(RV L.198)

RV L3 Approximation method for the ultimate limit state (RV 1) By way of simplification, the reinforcing steel tension can be obtained from the prestrain by means of Equation Error: Reference source not found from the moment during reinforcement to serviceability level.

σ s,0( x )=MEqp,0( x )

zs⋅A s=

M Eqp,0( x )0 .85⋅d⋅As

≤f yd

(RV L.199)

(RV 2) The effective moment after reinforcement may be obtained by means of Equation Error: Reference source not found.

ΔM Ed( x )=M Ed,V( x )−M Eqp,0( x )(RV L.200)

(RV 3) By way of simplification, the reinforcing steel tension in the reinforced state can be obtained by means of Equation Error: Reference source not found.

σ s( x )=σs,0 ( x )+ΔMEd( x )

zm⋅

d⋅E s

d L⋅ELm⋅A L+d⋅ES⋅AS≤f yd

(RV L.201)

Where

zm≈0. 75⋅d L⋅ELm⋅A L+d⋅ES⋅AS

ELm⋅AL+ES⋅AS (RV L.202)(RV 4) By way of simplification, the plate force as a function of reinforcing steel tension in the reinforced state can be obtained by means of Equation Error: Reference source not found.

FLEd (x )=(

ΔM Ed( x )zm

⋅dL⋅ELm⋅AL

dL⋅ELm⋅AL+d⋅ES⋅ASfor σ s( x )< f yd

M Ed,V ( x )zm

−A s⋅f yd for σ s( x )≥f yd(RV L.203)

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DafStb Guideline onon the reinforcement of concrete parts with adhesive bonding

Part 2: Products and systems for reinforcement

Draft March 2012



Published by:Deutscher Ausschuss für Stahlbeton e. V. – (DAfStb) Budapester Straße 31D – 10787 Berlin-TiergartenPhone: 030 [email protected]


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Contents List Part 21 Scope of application.............................................................................................902 Normative references............................................................................................903 Reinforcement system..........................................................................................90

3.1 General........................................................................................................................903.2 Adhesive.....................................................................................................................903.3 CFRP plates................................................................................................................913.4 CF sheeting................................................................................................................913.5 Products for levelling layers.....................................................................................923.6 Primer for corrosion protection................................................................................923.7 Steel sections and fastening systems.....................................................................93

DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding – Part 2: Products and systems for reinforcement

1 Scope of application(1) This part of the Guideline contains a general description of products and systems for reinforcement of concrete parts with adhesive bonding.

(2) Application of this Guideline in areas subject to building inspectorate approval shall require a general building inspectorate approval as usability verification of the reinforcement systems.

(3) The requirements for products and systems for reinforcement of concrete parts in accordance with general building inspectorate approvals shall be satisfied.

2 Normative referencesDIN 1045-2, Plain, reinforced and prestressed concrete structures – Part 2: Concrete – Specification, properties, production and conformity – Application rules for DIN EN 206-1DIN 18551, Shotcrete - National rules for series DIN EN 14487 and rules for design of shotcrete constructions DIN EN 206-1, Concrete - Part 1: Specification, performance, production and conformityDIN EN 1993-1-1, Eurocode 3: Design of steel structures - Part 1-1: General rules and rules for buildings DIN EN 2561, Aerospace series - Carbon fibre reinforced plastics - Unidirectional laminates - Tensile test parallel to the fibre direction DIN EN 10025-2, Hot rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steelsDIN EN 14487-1, Sprayed concrete - Part 1: Definitions, specifications and conformity

3 Reinforcement system

3.1 General(1) A reinforcement system consists of different construction products matched to each other. Proof of their suitability as part of the reinforcement system shall be furnished within a general building inspectorate approval of the reinforcement system (e.g. general building inspectorate approval or permit in individual cases). The Guideline wording will generally use the term ‘general building inspectorate approval’ for this purpose.

(2) The products of the reinforcement system shall bear a mark of conformity [German designation: Ü-Zeichen] from the manufacturer in accordance with the regulations on marks of conformity of the respective states.

(3) A reinforcement system consists of:

Reinforcement elements made of carbon fibre materials (CFRP plates or CF sheeting) or flat steel sections (steel tabs or angle steel);

the adhesive; a primer on epoxy resin basis as part of the corrosion protection system for steel parts; reprofiling mortar on an epoxy resin basis including screed.

3.2 Adhesive(1) Only adhesives approved for the application shall be used in the adhesive bonding of reinforcement sections. The requirements of adhesives are regulated in the general building inspectorate approvals.

(2) The following information shall be available on the adhesive:

product designation and manufacturer; batch number; date of minimum durability; minimum and maximum application temperatures: mixture ratio of epoxy resin and curing agent;

90


reference to occupational regulations (Code) and hygiene; information on storage; mixing instructions; pot life within the application temperature; danger warnings; disposal instructions. (3) The Guideline shall only be applied if the characteristic tensile strength of an adhesive on epoxy resin basis for the surface bonding of reinforcement sections ≥ 14 N/mm2 is verified within in-house production control in accordance with general building inspectorate approvals.

NOTE: Establishing a minimum value for the characteristic tensile strength will ensure that the basic assumption of design, namely that the concrete layer close to the surface will fail, has been satisfied.

(4) For plates bonded in indent cuts, the respective characteristic values for compressive and tensile strength can be found in the general building inspectorate approvals.

3.3 CFRP plates (1) The carbon fibre reinforced plates (CFRP plates) shall be factory-manufactured sections made of epoxy resin containing a specific amount of unidirectional carbon fibres as defined in product approvals. The plates are characterised by

their mechanical properties in the direction of the fibres (tensile strength, modulus of elasticity, ultimate strain);

the characterisation of the matrix resin (binding agent type, glass transition temperature) their geometric dimensions (plate thickness and width); their surface design (smooth, polished, profiled). (2) Corresponding definitions are included in the respective general building inspectorate approvals or the manufacturer’s instructions.

(3) The design equations in Part 1 of this Guideline apply to CFRP plates with a thickness between 1 mm and 3 mm.

(4) The mean modulus of elasticity of the CFRP plates determined in accordance with DIN EN 2561 must be in a range of 150 to 230 kN/mm² if this Guideline is applied.

3.4 CF sheeting(1) The carbon fibre sheets (CF sheeting) are unidirectionally aligned carbon fibres. The sheeting is characterised by the following properties:

tensile strength in the direction of fibres; modulus of elasticity in the direction of fibres; ultimate strain in the direction of fibres; geometric dimensions and weight per area calculated thickness (equals theoretical thickness) (2) Corresponding definitions are included in the respective general building inspectorate approvals or the manufacturer’s instructions.

(3) When using confinement in the reinforcement columns, the following additional system coefficients shall be substituted with the system-specific factors from the general building inspectorate approvals:

[k0] factor for determining the minimum thickness of the confining reinforcement to ensure the strictly monotonous increase in the stress-strain relations of confined concrete, which underlies the design concept.

[k1] factor for determining characteristic compressive strength of confined concrete [k2] factor taking into account the effect of component edge conditions on the presumable limit

strain of CF sheeting[k3] factor taking into account the effect of temperature on the presumable limit strain of CF

sheeting[k4] factor taking into account the effect of moisture on the presumable limit strain of CF

sheeting

91


[k5] factor taking into account the effect of action type (predominantly static or non-static) on the presumable limit strain of CF sheeting

[k6] factor taking into account the effect of duration of actions on the applicable limit strain of CF sheeting

[k7] factor for determining the effective creep of confined concrete [k8], [k9] factors for determining the loadbearing component of the confined column that will not

result in damage in the serviceability limit state

3.5 Products for levelling layersTo re-establish the profile of defective spots in the substrate to which the plate is bonded or imbedded in, the following products with verified properties may be used:

Repair concrete or mortar of strength class M3 in accordance with the Repair Guideline, Part 2: construction products and application, Section 4.2;

Concrete in accordance with DIN EN 206-1/DIN 1045-2 taking into account the respective exposure class;

Cement-bound concrete and grouting mortar in accordance with DAfStb Guideline “Production and use of cement-bound grouting concrete and grouting mortar”, taking into account the respective exposure class;

Sprayed concrete in accordance with DIN EN 14487-1 in combination with DIN 18551 taking into account the respective exposure class;

Repair mortar in accordance with general building inspectorate approvals may be used to repair the profile of small-area surface irregularities.

3.6 Primer for corrosion protection (1) Primer approved for the application shall be used in the corrosion protection of steel section. The requirements of primers are regulated in the general building inspectorate approvals.

(2) The Guideline shall only be applied if the characteristic tensile strength of the primer for steel sections ≥ 14 N/mm2 is verified within in-house production control in accordance with general building inspectorate approvals.

(3) The following information shall be available on the primer:

product designation and manufacturer; batch number; date of minimum durability; minimum and maximum application temperatures: mixture ratio of epoxy resin and curing agent; reference to occupational regulations (Code) and hygiene; information on storage; mixing instructions; information on curing period until characteristic tensile strength is reached; pot life within the application temperature; danger warnings; disposal instructions.

3.7 Steel sections and fastening systems (1) Steel sections shall be made of S235 steel, quality class JR or J2 in accordance with DIN EN 10025-2. The characteristic material data for S235 steel in accordance with DIN EN 10025-2 can be found in DIN EN 1993-1-1, Table 3.1.

(2) S355 steel in accordance with DIN EN 10025-2 may also be used. For the design, no material characteristics higher than those in DIN EN 1993-1-1, Table 3.1 may be used for S235 steel.

(3) Grade JR steel in accordance with DIN EN 10025-2, analogous to use of J2 steel with a steel tab thickness tL ≤ 15 mm may be used under the following conditions:

use in components subject to predominantly static actions

92


the nominal yield strain in the panel in the ultimate limit state will be limited to 80 %. (4) If steel parts are to be anchored on the component, fastening systems approved for the application in general building inspectorate approvals shall be used. The anchor screws shall comply with strength class 4.6, 5.6, 8.8 or 10.9.

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Part 3: Construction

Draft March 2012



Published by:Deutscher Ausschuss für Stahlbeton e. V. (DAfStb) Budapester Straße 31D – 10787 Berlin-TiergartenPhone: 030 [email protected]


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DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding - Part 3: Execution

Contents List Part 31 Scope of application.............................................................................................932 Normative references............................................................................................933 Requirements for the contractor..........................................................................93

3.1 General........................................................................................................................933.2 Staff.............................................................................................................................94

3.2.1 Project supervisor..........................................................................................................943.2.2 Skilled site personnel.....................................................................................................94

3.3 Equipment..................................................................................................................953.4 Subcontractor............................................................................................................95

4 Execution of the component reinforcements......................................................954.1 General........................................................................................................................954.2 Requirements on the reinforcement system...........................................................964.3 Climate and ambient conditions...............................................................................964.4 Substrate priming......................................................................................................96

4.4.1 Bonding of CFRP plates or steel tabs to component surface using adhesive................964.4.2 Bonding of CF sheeting.................................................................................................974.4.3 Bonding in indent cuts in the concrete edge zone.........................................................97

4.5 Reprofiling work.........................................................................................................984.6 Priming of fibre composite materials and steel tabs for adhesive bonding........98

4.6.1 CFRP plates.................................................................................................................. 984.6.2 Steel tabs.......................................................................................................................994.6.3 CF sheeting................................................................................................................... 99

4.7 Mixing the adhesive...................................................................................................994.8 Adhesive work............................................................................................................99

4.8.1 General determinations.................................................................................................994.8.2 Bonding of CFRP plates or steel tabs to component surface using adhesive................994.8.3 Bonding of CF sheeting to component surface using adhesive...................................1004.8.4 CFRP plates bonded in indent cuts.............................................................................100

4.9 Actions on the structure.........................................................................................1004.10 Component exposures during execution..............................................................1014.11 Limit deviations........................................................................................................101

5 Supervision of the execution (contractor’s internal control).............................1015.1 General requirements..............................................................................................1015.2 Supervision of substrate priming...........................................................................102

5.2.1 Check of concrete compressive strength.....................................................................1025.2.2 Check of the surface tensile strength of the substrate.................................................1025.2.3 Check of the concrete cover prior to cutting work performed for reinforcement bonded in indent

cuts.............................................................................................................................. 102

5.3 Check of the reprofiling work.................................................................................1045.3.1 Check of bond strength between reprofiled layer and substrate..................................1045.3.2 Check of the compressive strength of the reprofiling material.....................................104

5.4 Supervision of the adhesive work..........................................................................1055.4.1 Curing test of the adhesive on the component, with levelling layer, if necessary.........1055.4.2 Mechanical properties of the adhesive and primer......................................................105

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5.4.3 Adhesive bond on pretreated steel..............................................................................106

5.5 Checks after execution............................................................................................1065.6 Corrosion protection work......................................................................................107

Annex A Permanent inspection body (normative)..............................................108Annex B Test methods during execution (normative)........................................109Annex C Supervision of work by an accredited inspection body (normative)...110Annex D Certificate of suitability for contractors for reinforcement of concrete

components using adhesive bonding (normative)............................................111D.1 General......................................................................................................................111D.2 Formal requirements for the operation and the skilled personnel.....................111D.3 Suitability tests........................................................................................................112D.4 Certification of the contractor................................................................................114

1 Scope of application...........................................................................................1242 Normative references..........................................................................................1243 Requirements of the component to be reinforced.............................................124

3.1 Special regulations for steel tabs, CFRP plates and CF sheeting bonded to a surface................................................................................................................................124

3.2 Special rules for CFRP plates bonded in indent cuts..........................................124

4 Principles.............................................................................................................1254.1 General......................................................................................................................125

Annex A Determination of the expected mean value..........................................126

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Foreword

(1) The requirements and data in the product and system approvals shall be observed.

(2) The usage conditions for the application of the system are included in the approvals.

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1 Scope of applicationThis part of the Guideline establishes rules for the execution of reinforcement measures for parts using adhesive bonding.

2 Normative referencesDIN 1045-2, Plain, reinforced and prestressed concrete structures – Part 2: Concrete – Specification, properties, production and conformity – Application rules for DIN EN 206-1DIN 1045-3, Plain, reinforced and prestressed concrete structures – Part 3: Execution of structuresDIN 18551, Shotcrete - National rules for series DIN EN 14487 and rules for design of shotcrete constructionsDIN 18800-7, Steel structures - Part 7: Execution and manufacturer qualification DIN V 18028, Injection products according to DIN EN 1504-5:2005-03 with special features DIN EN 196-1, Methods of testing cement - Part 1: Determination of strength DIN EN 206-1, Concrete - Part 1: Specification, performance, production and conformityDIN EN 1504-5, Products and systems for the protection and repair of concrete structures - Definitions, requirements, quality control and evaluation of conformity - Part 5: Concrete injection DIN EN 1542, Products and systems for the protection and repair of concrete structures - Test methods - Measurement of bond strength by pull-off DIN EN 1766, Products and systems for the protection and repair of concrete structures - Test methods - Reference concretes for testing DIN EN 1990, Eurocode: Basis of structural design DIN EN 1992 1-1, Eurocode 2: Design of concrete structures - Part 1-1: General – Common rules for building and civil engineering structuresDIN EN 10025-2, Hot rolled products of structural steels - Part 1: Technical delivery conditions DIN EN 13670, Execution of concrete structures DIN EN 13791, Assessment of in-situ compressive strength in structures and precast concrete components DIN EN 14487, Sprayed concrete - Part 1: Definitions, specifications and conformityDIN EN ISO 12944-2, Paints and varnishes - Corrosion protection of steel structures by protective paint systems - Part 2: Classification of environments DIN EN ISO 12944-4, Paints and varnishes - Corrosion protection of steel structures by protective paint systems - Part 4: Types of surface and surface preparation DIN EN ISO 12944-7, Paints and varnishes - Corrosion protection of steel structures by protective paint systems - Part 7: Execution and supervision of paint work

RiLi SIB, DAfStb Guideline ‘Protection and repair of concrete components’ (‘Schutz und Instandsetzung von Betonbauteilen’), October 2001 edition

3 Requirements for the contractor

3.1 General(1) Requirements with regard to staff, equipment and documentation are imposed on the contractor regarding the execution and supervision of reinforcement using adhesive bonding.

(2) Evidence of qualification of the contractor shall be issued by an inspection body certified by the German Institute of Structural Engineering (Deutsches Institut für Bautechnik (DIBt))

through certification in accordance with the manufacturer and user regulation (HAVO) on the repair of loadbearing components the stability of which is in danger

a suitability certificate for reinforcement of concrete components reinforced by adhesive bonding (requirements in accordance with Annex D).

(3) Only products approved and tested in the system may be used for reinforcement measures using adhesive bonding.

- (4) The manufacturer’s information on the execution according to the rules of general building inspectorate approvals for reinforcement systems shall be complied with.

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3.2 Staff3.2.1 Project supervisor(1) The tasks and responsibilities of the project supervisor are regulated in the respective Regional Building Regulations. If the project supervisor does not possess the required technical knowledge in accordance with the provisions of the section, a competent and experienced technical project supervisor shall be consulted.

(2) The tasks of the project supervisor as the qualified project manager for reinforcement measures using adhesive bonding are in particular:

checking materials and components used for conformity with the information in the construction documentation and examination of performance specifications in the meaning of this Guideline;

planning work flows based on the planning documentation for the reinforcement measures created by a competent planner;

use of intended material with the required certificates of conformity; initiating the required tests, if necessary in consultation with an inspection body in accordance with

Annex A; reporting of the repair measure to the inspection body; evaluation of technical qualification of construction site personnel used for the measure; analysis of results of internal control at the contractor and drawing of conclusions from the results for

further proceedings; submission of the results of internal control to the inspection body. (3) The manager responsible shall be certified as a qualified manager in the suitability verification of the contractor in accordance with Annex D.

3.2.2 Skilled site personnel (1) There shall always be a skilled contractor’s employee who is especially trained in construction work present on each construction site at all times, who possesses knowledge, skills and practical experience in concrete and other construction material technology, as well as in the use of the designated products. Proof of the capability to work in accordance with this Guideline shall be furnished to the recognised inspection body in the form of the following two certificates:

certificate issued by the training committee for “using plastics in concrete construction” [“Verarbeiten von Kunststoffen im Betonbau”] from Deutscher Beton und Bautechnik-Verein E. V. in the form of the SIVV-Schein (protection, repair, joining and reinforcement of components). Provisions regarding regular continuing education shall be observed.

Suitability verification of the skilled personnel for reinforcement of parts using adhesive bonding in accordance with Annex D.

(2) Tasks of skilled personnel include the practical execution of the reinforcement measure according

to specifications in the planning and execution documentation, such as work plan, execution instructions;

instruction and supervision of other construction site personnel and/or subcontractor(s) responsible for executing the reinforcement measure;

conducting of tests required for internal control and recording of the results. (3) The contractor’s skilled personnel responsible for working according to this Guideline shall be certified as skilled personnel with special knowledge and experience in:

the repair of loadbearing components in accordance with RiLi SIB. This evidence may be furnished in the form of a certificate for “using plastics in concrete construction” [“Verarbeiten von Kunststoffen im Betonbau” (SIVV-Schein)] from Deutscher Beton und Bautechnik-Verein E. V. and

reinforcement of parts using adhesive bonding according to the provisions in Annex D. - (4) The contractor shall furnish evidence that the skilled personnel responsible will receive training

and education in protection and reinforcement measures at intervals of no more than three years, enabling them to carry out all measures necessary for proper execution of a reinforcement measure including internal control.

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3.3 Equipment

(1) For the execution of reinforcement work using adhesive bonding, the implements and equipment that allow proper priming of substrate, skilled carrying out of work, determination of required properties of materials and checking work results shall be at the site in a functional state and at the required time. In particular, these are equipment and implements for

storage of construction materials; preparation of the substrate; measuring and mixing products; processing and after-treatment of processed products; performance of proper internal control. (3) All equipment and implements shall be checked for proper function prior to their initial use and then at regular intervals thereafter.

Table 3.6 Recommended equipment for operations (informative)

Recommended implements 1 Hygrometer2 Thermometer for air and component temperatures 3 Crack width meter (template), magnifying glass for measurement purposes4 Instruments for measuring material or component moisture, e.g. CM meter (see Annex B)

5 Adhesive pull strength tester including test pieces 20 mm and 50 mm and a Sa3 blasted steel plate with a thickness of 15 mm

6 Sample specimen forms 40 mm x 40 mm x 160 mm in accordance with DIN EN 196-1 and accessories 7 Storage facilities for test specimens or climate chamber

8 Scales with a 20 capacity and a minimum readout accuracy of 1 g. NOTE: The weighing of individual components on the site in exceptional cases only.

9 Core drilling machine and accessories (also suited for overhead use, if applicable)

10 Equipment for substrate priming, e.g. by chiselling, blasting, milling, grinding and for cleaning, as well as tools for cutting indents

11 Suitable mixing equipment for different products 12 Implements for conveying, applying, smoothing, spreading 13 Stud finder14 Flatness measuring device

3.4 Subcontractor (1) If the contractor hires subcontractors for subprojects, the contractor shall make sure that the subcontractor satisfies the requirements in accordance with Sections Error: Reference source not found through Error: Reference source not found.

(2) Only skilled personnel with a suitability certificate on the reinforcement of concrete components in accordance with Annex D of a contractor certified in accordance with Section Error: Reference source not found may carry out the adhesive bonding work.

4 Execution of the component reinforcements

4.1 General(1) As part of the execution, a comparison of values obtained from internal control of execution in accordance with Section Error: Reference source not found with the random sample values obtained in the planning phase shall be used to check whether they are representative for the actual state of the component (plausibility check). In the event of deviation, these shall be reported to the customer, so that the competent planner may review the planning documents and revise them, if needed.

(2) Prior to the reinforcement measure, the contractor or subcontractor shall develop a standard operating procedure with information on the execution.

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4.2 Requirements on the reinforcement system (1) The requirements on the reinforcement system (fibre composite materials, steel tabs, adhesive, corrosion protection, levelling mortar) are specified in the general building inspectorate approvals, in particular:

mechanical properties;

application and processing temperatures;

moisture conditions;

roll diameter of the fibre composite material or bending diameter of the steel tabs;

if applicable, protective layers for certain exposures of the reinforced component area.

(2) For each reinforcement system, the manufacturer or system supplier of the products shall provide “information on execution” (formerly: execution instructions). They shall contain all the information necessary for execution in the meaning of usability verification. Execution data for certain materials may contain additional requirements on the concrete substrate, the climate conditions and/or provisions on the limitation of vibrations.

4.3 Climate and ambient conditions (1) During application and for an appropriate period thereafter, the temperatures of the concrete substrate and the air layer immediately above it shall be at least 8 °C and the maximum component moisture 4 %. When using plastic-bound materials, the surface temperature of the concrete or the respective substrate shall always be at least 3 K above the dew point. The air humidity must not exceed 75 %. If applicable, deviating values shall be specified in the general building inspectorate approvals.

(2) With regard to limit values, the temperature development over the period of execution and for an appropriate period thereafter as well as cooling off overnight shall be taken into account (based on weather forecasts, taking into consideration regional conditions).

(3) If vibrations (e.g. from construction work or traffic) are expected during curing of the potential levelling layer, these shall be mitigated or eliminated as necessary to avoid damage to the adhesive bond.

4.4 Substrate priming

4.4.1 Bonding of CFRP plates or steel tabs to component surface using adhesive (1) For reinforcement measures on concrete component using adhesive bonding to be successful with regard to type, quality and duration, the respective concrete surface must have certain properties. This will require substrate priming.

(2) The concrete surface shall be primed for the adhesive until the grain particles with a diameter > 4 mm become visible; this can be achieved for example for example by

blasting with solid blasting materials, shot blasting, treatment with a blasting gun, grinding. (3) Cracks in the concrete in the reinforcement zone that might result in corrosion in the reinforcement or cracks with liquid penetration shall be treated in accordance with RiLi SIB.

(4) The concrete surface to be bonded shall be free from dust and loose particles. Furthermore the concrete surface shall be dry in the meaning of RiLi SIB. The moisture content of the component shall not exceed 4 % (see Error: Reference source not found (1)). There must be no cracks or material detachments parallel to the surface or shell-shaped near the surface, or any foreign particles such as rubber debris, removal agents, unsuitable old coatings, efflorescence, oil, growth etc. that could impair the adhesive bond.

(5) After substrate priming, the surface tensile strength of the concrete substrate shall be checked in accordance with DIN EN 1542. The expected mean surface tensile strength of the concrete or the reprofiled concrete surface in the zone of the adhesive bonding shall be evaluated in accordance with Part 4 of this Guideline. The expected mean surface tensile strength shall be at least 1.0 N/mm2. If a higher value is used in the static calculation of the adhesive bond, an analysis shall be conducted for it. If the required surface tensile strength cannot be attained, the competent planner shall be notified prior to performing the adhesive

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work. Additional tests may be necessary. Lower values may be an indication of insufficient component stability.

(6) The surface of the concrete to be bonded by adhesive should be as large as possible (see (8)). If necessary, a levelling layer in accordance with section Error: Reference source not found shall be installed.

(7) Unevenness up to 4 mm may be levelled by the adhesive.

(8) Unevenness in the range between 4 and 30 mm shall be levelled by grinding or reprofiled using a levelling layer in accordance with Section Error: Reference source not found. Unevenness > 30 mm shall be evaluated by the structural engineer. Exempt from this are spot defects in the concrete, such as reprofiled concrete chips or pits. These shall be exposed properly and reprofiled.

4.4.2 Bonding of CF sheeting (1) The provisions in Error: Reference source not found. shall apply to the adhesive bonding of CF sheeting. Cement-bound concrete substitutes or concrete as a substrate shall be primed by grinding prior to bonding.

(2) Suitable methods for substrate priming are grinding, blasting or jet blasting. Cement slurry shall be removed until the grain structure becomes visible. Unevenness or indentations of 3 mm or more shall be reprofiled using a suitable epoxy resin mortar in accordance with general building inspectorate approvals. Over a test section of 300 mm, the variation from flatness must not exceed 1 mm. The corners of column confinements shall be curved at a radius of r ≥ 25 mm. At the time of adhesive bonding, the surfaces shall be dry (residual moisture < 4 %) and free from dust and particles. The adhesion strength values shall be adjusted to the values assumed in the static calculation.

4.4.3 Bonding in indent cuts in the concrete edge zone (1) The CFRP plates shall be bonded perpendicular to the concrete edge zone. For this purpose, indents perpendicular to the component need to be cut into the component surface.

(2) The concrete cover of the existing reinforcing steel reinforcement shall be so that the reinforcement will not be damaged by the cutting work. An analysis of the concrete cover in the area of the plates to be bonded in indent cuts shall be conducted and the results documented.

(3) The following parameters shall be observed:

The depths of the cut in the concrete shall be designed so that the plate can be fully embedded in the cut, taking into account the levelling of irregularities. The maximum permissible cut depth ts is obtained as follows:ts ≤ c – Δcdev

Where

c: existing concrete cover of reinforcement in mm

cdev: allowance in design for deviation in mm

cdev = cdevice + ccut + ccomponent

Where:

cdevice device-specific defect limit, [DBV-Merkblatt ‘Betondeckung’] or manufacturer’s information, minimum 1 mm

ccut allowance in design for deviation, minimum 2 mm

ccomponent for slabs, ccomponent = 0 mm is permissible, for all other components, the assumption is ccomponent minimum 2 mm.

ccomponent may be omitted if the accuracy of the concrete cover measurement can be increased by suitable measures, e.g. random sampling of concrete cover through spot exposure of the reinforcement.

The width of the indent cut bs shall satisfy the following condition:tL + 1 mm ≤ bs ≤ tL + 3 mm

Where

tS depth of the cut in mm (see above)

tLplate thickness in mm

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(4) The indent cuts shall be free from dust and particles. Non-loadbearing layers on the side surfaces of the cut shall be removed. The maximum moisture content in the indent cut zone shall not exceed the values in the product approval.

4.5 Reprofiling work (1) Reprofiling work on the substrate may be necessary if there are defect spots in the existing concrete, such as concrete chipping and pits; unevenness in the component surface does not allow even adhesive bonding of the reinforcement to

satisfy the requirements in accordance with Section Error: Reference source not found; even after substrate priming, irregular or defective spots over 4 mm remain; the concrete cover is insufficient. (2) Uneven or defective spots in the substrate of less than 4 mm may be levelled with an adhesive in accordance with Section Error: Reference source not found. Unevenness or defective spots in the substrate greater than 4 mm shall be levelled by grinding or reprofiling.

(3) Reprofiling serves the purpose of static loadbearing capacity. To level out small- or large-area unevenness in the concrete surface or defects in the adhesive area, only the following materials may be used, provided the necessary bond strength of the concrete substrate is reached and an analysis for large-area reprofiling is provided in accordance with Section Error: Reference source not found:

Repair concrete or mortar of strength class M3 in accordance with RiLi SIB, Part 2: construction products and application, Section 4.2;

Concrete in accordance with DIN EN 206-1/DIN 1045-2 taking into account the respective exposure class;

Cement-bound concrete and grouting mortar in accordance with DAfStb Guideline “Production and use of cement-bound grouting concrete and grouting mortar”, taking into account the respective exposure class;

Sprayed concrete in accordance with DIN EN 14487 in combination with DIN 18551 taking into account the respective exposure class.

Repair mortar in accordance with general building inspectorate approvals may be used to repair the profile of small-area unevenness.

(4) RiLi SIB shall apply for the performance of reprofiling work.

(5) For large-area levelling layers, the roughness of the substrate specified by the competent planner shall be prepared.

4.6 Priming of fibre composite materials and steel tabs for adhesive bonding

4.6.1 CFRP plates(1) The CFRP plates must not be pressed off or subjected to sharp transverse pressing. If applicable, they only may be cut perpendicular to the direction of fibre on the construction site.

(2) Prior to bonding, the plate surface shall be primed in accordance with the general building inspectorate approval.

NOTE When using solvents, the occupational health protection provisions of the German Employer’s Liability Insurance Association shall apply.

4.6.2 Steel tabs(1) The material of the steel parts to be bonded and the anchor bolts for mounting them can be found in the general building inspectorate approval.

(2) Welding work on steel parts to be joined shall only be performed by companies that possess proof of manufacturer qualification in accordance with DIN 18800-7, Class B. Welding work on bonded steel parts is not permissible.

(3) Prior to bonding, steel parts shall be blasted with solid particles until they reach a purity level of Sa 2½ in accordance with DIN EN ISO 12944-4.

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(4) Steel parts for external use shall be coated twice on both sides with a minimum layer thickness of 120 µm of a primer approved according to general building inspectorate approvals. Upon curing of the primer, it shall be ground on the surfaces to be bonded. However, it must not be ground for exterior use. Prior to bonding, the ground surfaces shall be dusted and cleaned using a solvent in accordance with manufacturer’s specifications.

(5) For internal use (XC1), a procedure in accordance with Section (4) is permissible. Full coating with a primer may be foregone in internal use (XC1) if the steel parts are bonded immediately upon blasting or if the steel parts are protected from corrosion by sealing in PE foil until bonding.

(6) After bonding of the steel tabs, the non-bonded steel surfaces shall receive additional corrosion protection of C3 or higher in accordance with DIN EN ISO 12944-2. This corrosion protection shall be applied to the component surface over and up to 10 mm of the adhesive thickness to the left and right of the steel tab.

NOTE When using solvents, the occupational health protection provisions of the German Employer’s Liability Insurance Association shall apply.

4.6.3 CF sheeting(1) The CFRP sheeting must not be rounded off or subjected to sharp transverse pressing.

(2) The sheeting surface shall be free from dust prior to adhesive bonding.

(3) Additional information of the respective general building inspectorate approvals shall be taken into account.

4.7 Mixing the adhesive (1) The temperature range recommended by the manufacturer for mixing the adhesive shall be complied with. If the adhesive temperature is below that, additional mixing might be necessary.

(2) Mixing of the adhesive components shall be done mechanically using a slow-speed (< 300 rpm) mixer. The components shall be mixed until a homogenous and ream-free adhesive mass is obtained. The mixture must be moved to a different container. The finished mixture must not contain lumps or similar; its colour shall be even.

(3) No significant air volumes shall be mixed in.

4.8 Adhesive work

4.8.1 General determinations(1) During the adhesive work, the minimum temperatures of air and concrete and the maximum values of relative air humidity according to general building inspectorate approvals must be observed. The temperature of the component shall be 3 K higher than the dew point temperature of the air.

(2) The substrate of the concrete in the adhesive bonding zone shall be dry in the meaning of RiLi SIB. If in doubt, a quantitative determination of the moisture content shall be conducted. The permissible moisture content can be found in the general building inspectorate approvals.

4.8.2 Bonding of CFRP plates or steel tabs to component surface using adhesive(1) Prior to bonding of the tabs or plates, a coat of adhesive shall be applied to the substrate with a notched trowel to completely fill all valleys and small defects with the adhesive. If the surface has been ground, coat application with a trowel may be foregone. The grain structure shall be visible in the ground surfaces and the adhesive pull strength tests in accordance with Section Error: Reference source not found shall be conducted on the ground surfaces.

(2) The adhesive shall be applied to the tab or plate in the shape of a roof; that is, an equal angle profile with a camber. Within the open time, the tabs or plates shall be pressed carefully and evenly into the scraped, fresh adhesive layer. The adhesive is pushed out of the joint evenly forming a little bulge, to form a cured adhesive layer with a total thickness of 1 mm to 5 mm maximum.

(3) The adhesive shall be applied to the components and the components secured in their final position within the open time according to the respective product specifications. After securing until the adhesive or the reprofiling layer underneath have cured, the components must not be subjected to vibration or movement that could damage the bond.

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(4) For reinforcement using steel tabs, a support for the adhesive curing period will be required in accordance with the provisions of the general building inspectorate approvals. The support period may be shorter if adhesive pull tests according to Section Error: Reference source not found show that concrete failure has been achieved.

(5) CFRP plates may be bonded without further support.

(6) CFRP plates may be bonded in two layers only if specified in the static analysis. In this case, after curing of the first bonded plate, its smooth and imprinted secondary bonding side shall be carefully roughened and cleaned and degreased using a solvent in accordance with the manufacturer’s instructions. Any packaging fabric on this side shall be removed. Further priming will not be necessary in this case. The second plate layer shall be primed and bonded as described.

(7) In areas where the risk of mechanical damage after installation cannot be precluded, the plates shall be protected against mechanical damage.

4.8.3 Bonding of CF sheeting to component surface using adhesive(1) Depending on the system approval, a primer shall be applied prior to application of laminating resin. Waiting times are in accordance with the respective general building inspectorate approvals. Depending on the CF sheeting type, protective foils shall be removed and the sheeting worked into the fresh laminating resin using a suitable tool such as a roller or rubber lip. Care should be taken that no folds or hollow pockets form. The applied CF sheeting shall then be embedded in a layer of laminating resin. If several layers are required, the above steps shall be repeated. The maximum and minimum temperature and humidity values and application amounts can be found in the respective general building inspectorate approvals. (2) In areas where the risk of mechanical damage after installation cannot be precluded, the sheeting shall be protected against mechanical damage.

4.8.4 CFRP plates bonded in indent cuts(1) The adhesive shall be applied to the cut to completely fill it. Within the open time, the plate shall then be carefully pressed into the middle of the indent cut. It must be completely embedded by the indent cut.

(2) The bonded plate will not require securing while curing. In areas where the risk of mechanical damage after installation cannot be precluded, the plates shall be protected against mechanical damage.

(3) Only products approved and tested in the system may be used for reinforcement using adhesive bonding.

4.9 Actions on the structure (1) At component surface temperatures or mean air temperatures near the surface of 20 °C, actions on the structure are usually permissible 2 days after completion of the adhesive work.

(2) At lower temperatures, the curing time may be longer, and at higher temperatures, the waiting time may be shorter. The curing analysis on the component in accordance with Section Error: Reference source not foundwill determine the length of time.

(3) Actions on the reinforced structure are permissible after the levelling layer possesses sufficient strength. This will be the case when the characteristic strength of the product is higher than the compressive strength of the existing concrete and the bond strength with the substrate is greater than the nominal static bond strength. This may have to be demonstrated in accordance with Section Error: Reference source not found.

4.10 Component exposures during execution During execution of reinforcement measures using adhesive bonding, the reinforced component areas shall be protected from direct exposure to weather and mechanical loads.

4.11 Limit deviations The limit deviations in accordance with DIN EN 13670 or DIN 1045-3 shall apply. The limit deviations of component dimensions shall apply with regard to effective static depth.

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5 Supervision of the execution (contractor’s internal control)

5.1 General requirements(1) The contractor shall ensure that

the CFRP plates, CF sheeting, adhesive, primer and products used for levelling layers bear the mark of conformity;

the steel plates in accordance with DIN EN 10025-2 bear the CE-mark; the expiry date (manufacturing date plus storage period) has not expired; the specifications with regard to substrate priming, reprofiling and adhesive work as well as corrosion

and other protection measures have been satisfied. (2) A standard operating procedure with information on the execution shall be created prior to the reinforcement measure.

(2) Throughout the execution, the project supervisor, his substitute or the skilled site personnel shall keep continuous, transparent records on data relevant to quality and durability. They shall contain at least the following information:

Name, location and type of construction project; Names of the executing and supervising skilled site personnel; Designation of the reinforced component (beam, T-beam, field and/or column zone) Number and dimensions of the plates, sheets or steel tabs; Start and end of adhesive work; Climate conditions, air temperature, humidity, dew point; Component temperatures to reach curing of the adhesive and substrate moisture; Analysis of the materials used, including supplier plant, batch number and installation location of each

batch; Function analysis of implements used; Results of tests conducted in accordance with Section Error: Reference source not found through Error:

Reference source not found with allocation to individual components or construction zones; Verification of execution according to available planning documentation and standard operating

procedures; Documentation of deviations, if applicable. (3) The documentation shall be available on the construction site. Upon request, the documentation as well as delivery notes shall be made available to the representative of the inspection body or the competent planner. Upon completion of the work, relevant documentation shall be submitted to the customer for creating a construction log.

(4) Upon completion of the work, the results of major tests conducted within execution and supervision by the contractor shall be made available to the inspection body for review upon request.

(5) Type, scope and frequency of supervision of execution by the contractor are specified in Sections Error: Reference source not found to Error: Reference source not found, unless otherwise stipulated in standards DIN 1045, DIN 18551, RiLi SIB or DAfStb Guideline “Production and use of cement-bound grouting concrete and grouting mortar”.

(6) Type, scope and frequency of tests in accordance with Error: Reference source not found shall only be specified prior to execution in consultation with the competent planner and the inspection body. This shall be documented. This shall also apply to the type of tests if it can be verified that deviating test methods are at least equivalent.

(7) In the event of deficient test results, the contractor shall determine their root cause. If their root cause is due to the condition of the structure, the competent planner shall be consulted for specification of further measures.

(8) Materials that do not meet the requirements shall be sorted out and marked as unsuitable.

(9) Operating equipment in accordance with Section Error: Reference source not found that does not satisfy the requirements shall be marked as unsuitable and must not be used.

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5.2 Supervision of substrate priming 5.2.1 Check of concrete compressive strength The concrete compressive strength of the components to be reinforced shall be checked for plausibility in non-destructive testing on the component in accordance with DIN EN 13791 within internal control.

5.2.2 Check of the surface tensile strength of the substrate The surface tensile strength shall be checked in at least 5 locations on the primed substrate in accordance with DIN EN 1542 using a snap ring groove. After priming of the bond surface, the surface tensile strength of the concrete shall satisfy the requirements in accordance with Section Error: Reference source not found (5).

5.2.3 Check of the concrete cover prior to cutting work performed for reinforcement bonded in indent cuts

(1) Concrete cover, location and diameter of the reinforcement shall be measured by non-destructive methods and recorded. Use of the instrument according to the user manual. The accuracy of the instrument shall be checked, e.g. next to exposed reinforcement or reinforcement to be exposed locally.

(2) Destructive testing of the concrete cover should be conducted in exceptional cases only.

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Table 5.7 – Type, scope and frequency of tests within internal control

Step Test

Bonding of CFRP plates

Bonding of CF

sheeting Bonding of steel tabs

Requirements Frequency Cuts in

concrete edge zone

On concrete surface

On concrete surface

Flat sections on concrete

surface

Angle steel on concrete surface

Sub

stra

te

prim

ing

Visual inspection x x x x x Suitability of substrate for planned measure -

Surface tensile strength O x x x x Acc. to Chapter Error: Reference source not found ≥ 5 individual tests total; ≥ 1 test per reinforced component/zone

Cracks x x x x xVisual inspection for irregularities or major deviations from planner’s records; No cracks that could cause corrosion in the steel reinforcement (see 2.4.1 (3))

-

Sur

face

repr

ofili

ng

Roughness prior to reprofiling x x x x x

≥ 0.5 mm for approved EP mortar and PCC M3;≥ 1.0 mm for shotcrete or concrete with screed;≥ 2.5 mm for concrete without screed;Test in accordance with DIN EN 1766 using sand surface method or visual inspection with reference areas;always in combination with bond tests.

≥ 1 m²:3 test for each 50 m²

Surface tensile strength x x x x x Acc. to Chapter Error: Reference source not found ≥ 5 individual tests total; ≥ 1 test per reinforced component/zone

Bond strength with substrate x x x x x In accordance with Chapter Error: Reference source not found

in accordance with Chapter Error: Reference source not found

Compressive strength x x x x x Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not found

Weather conditions during work x x x x xProduct-specific air temperature and humidity and component temperature and moisture in adhesive bond zone

Daily before work start and if in doubt, e.g. weather changes

Adh

esiv

e w

ork

Component surface before adhesive work

Moisture x x x x x Dry according to RiLi SIB or specification in adhesive approval Daily before work start and if in doubt

Temperature x x x x x Acc. to Chapter Error: Reference source not found Daily before work start and if in doubt, e.g. weather changes

Weather conditions x x x x x Acc. to Chapter Error: Reference source not found Daily before work start and if in doubt, e.g. weather changes

Curing test on component

Steel - adhesive - concrete O O O x x in accordance with Chapter Error: Reference source not found

in accordance with Chapter Error: Reference source not foundCFRP - adhesive -

concrete O x x O O

Bond test Adhesive - primer - steel O O O x x Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not found

Quality test Adhesive

Compressive strength x O O O OAcc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not

foundTensile strength x x x x xPockets in adhesive bond O O O x x Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not

found

Embedding of CFRP plates in indent cuts x O O O O Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not found

Layer thickness analysis for corrosion protection O O O x x Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not

found

Evenness of bonded tabs/plates O x O x O Acc. to Chapter Error: Reference source not found Acc. to Chapter Error: Reference source not found

x: test required; O: no test required

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5.3 Check of the reprofiling work

5.3.1 Check of bond strength between reprofiled layer and substrate (1) For adhesive bonds on large-area additions to the surface using products according to Part 1, Section 5.9, the bond strength of the concrete substitute in the primed area shall be determined by adhesive pull test in accordance with DIN EN 1542. The test scope shall be defined according to DAfStb Guideline ‘Protection and repair of concrete components’, Part 3, Annex A, Line 4.

(2) If concrete substitutes according to RiLi SIB are used for levelling layers, suitability tests and quality analysis shall be conducted accordingly. In addition to the suitability tests, bond strength tests shall be conducted to demonstrate the minimum bond strength required for the object. Performance of these analyses and their documentation are the responsibility of the material inspection body given in Annex A.

(3) For levelling layers in the anchorage zone according to Part 1, Section 6.2.5, an analysis of the bond between substrate and levelling layer shall be conducted. Adhesive pull test for bond strength in accordance with DIN EN 1542 in the edge zone of the concrete addition. The snap ring groove to be cut shall reach into the existing concrete. Due to higher requirements on the loadbearing capacity of the addition, the following tests shall be performed:

≥ 5 individual tests total or ≥ 1 for each 50 m bonded plate in the levelling layer zone; possible additional tests as determined by planner.(4) The test of bonded reinforcements in the anchorage zone of levelling layers shall result in failure of the existing concrete. If no failure occurs, the bond strength analysis shall be repeated according to Part 2 of the Guideline using the measured values.

(5) The test of CFRP plates bonded in indent cuts in the anchorage zone of levelling layers shall result in failure of the existing concrete. If no failure occurs, the required bond strength analysis shall be conducted. It shall be performed in accordance with DIN EN 1992 1-1 using the concrete compressive strength used in static analysis:

- fctk,surf,is fctk,surf = fctk,0,05 for concretes up to C50/60.(6) For small-area levelling layers, the bond strength fctm shall be 1.5 N/mm2. The test frequency is specified in DAfStb Guideline ‘Protection and repair of concrete components’, Part 3.

5.3.2 Check of the compressive strength of the reprofiling material (1) An analysis of the characteristic compressive strength of reprofiling material shall be furnished. Table 3.2 contains an overview of the requirements on the test specimens.

Table 5.8 – Requirements on the test specimens and test frequency for levelling layers

Levelling layer Test specimen Test frequency

Concrete in accordance with DIN 1045-2 Cube 150 mm x 150 mm x 150 mm

According to provisions ÜK 2 of DIN 1045-3

Sprayed concrete in accordance with DIN 18551

Core samples d = 100 mm from shotcrete slabs

SPCC of strength class M3 in accordance with RiLi SIB

Core samples d = 50 mm from shotcrete slabs

PCC of strength class M3 in accordance with RiLi SIB

V-blocks in accordance with DIN EN 196-1 3 V-blocks per batch or per

work day Grouting concrete with maximum particle size 6 mm

V-blocks in accordance with DIN EN 196-1

(2) When using V-blocks in accordance with DIN EN 196-1, the test values Rc shall be converted as follows for analysis of conformity based on sample specimen geometry according to DAfStb Guideline “Production and use of cement-bound grouting concrete and grouting mortar”

DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding - Part 3: Construction

fc,cube = 0.85 x Rc

Conformity assessment shall be carried out in accordance with DIN 1045-2, Section 8.2.1.3, using the smaller of the values.

Criterion 1: fc,m ≥ fc,k + 1.48

Criterion 2: fc,i 0.9 fc,k

Where

fck characteristic compressive strength to be assessed in accordance with Section 2.6, Annex 2 in N/mm2

fcm mean compressive strength in N/mm2

Standard deviation of the compressive strength values obtained

fc,i smallest compressive strength obtained in N/mm2

5.4 Supervision of the adhesive work

5.4.1 Curing test of the adhesive on the component, with levelling layer, if necessary (1) The curing of the adhesive bond under climate conditions on the component shall be tested prior to subjecting it to actions of adhesive pull tests in the layer structure. The test shall be conducted in 5 pull tests prior to action on the component. If the action on the component is to be applied in steps, a curing test shall be conducted after each step, at intervals in accordance with Error: Reference source not found. The adhesive pull test in accordance with DIN EN 1542 shall result in concrete failure after adhesive curing.

(2) For surface bonding of CFRP plates, 50 mm x 50 mm sections of the CFRP plate shall be glued to the concrete using the reinforcement adhesive. The test shall be conducted after creating a snap ring groove according to DIN EN 1542 that reaches into the substrate.

(3) For surface bonding of CF sheeting, minimum 300 mm x 300 mm sheet sections shall be applied in the number of layers to be used for component reinforcement. The test shall be conducted on a snap ring groove according to DIN EN 1542 that reaches into the substrate.

(4) For surface bonding of steel tabs, 50 mm punched steel pieces shall be glued to the concrete using the reinforcement adhesive.

(5) If levelling layers are used in the areas of CFRP plates, CF sheeting or steel stabs, the adhesive pull test shall be performed on the ‘concrete-levelling layer-adhesive-reinforcement element’ system.

5.4.2 Mechanical properties of the adhesive and primer (1) To verify the mechanical properties of the adhesive and primer used for steel tabs, a quality test shall assess

the tensile strength of reinforcements bonded to the surface the tensile and compressive strengths of reinforcement bonded in indent cuts as laid down in Error: Reference source not found.

(2) The tensile strength of the adhesive and primer shall be determined in an adhesive pull test using 20 mm test pieces, which are glued to a Sa 3 blasted steel plate with a thickness of 15 mm and tested after a curing time of 7 days. The assessment shall be carried out in at least 6 tests per adhesive batch used or 6 adhesive days each.

(3) The characteristic compressive strength fKc,k of the adhesive shall be obtained on V-blocks in accordance with DIN EN 196-1 after a curing period of 7 days. The assessment shall be carried out in at least 3 V-blocks per adhesive batch used or 3 adhesive days each.

Table 5.9 Mechanical characteristics of the adhesive and primer for the quality test under normal storage conditions 23 °C/50 % R.H.

Property Criterion 1 Criterion 2

Characteristic tensile strength fGtk in N/mm2 fGtk ≤ fGtm - kn sGt fGtk ≤ fGt,i / 0.9

Characteristic compressive strength fGck in fGck ≤ fGcm - kn sGc fGck ≤ fGc,i / 0.9

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N/mm2

fGtk characteristic tensile strength; there is a distinction between the following cases: a) characteristic tensile strength of the adhesive for plates bonded to a surface: 12 N/mm²b) characteristic tensile strength of the primer for steel tabs: 12 N/mm²c) characteristic tensile strength that was assessed in accordance with general building inspectorate approvals for the design of plates bonded in indent cuts

fGck characteristic compressive strength that was assessed in accordance with general building inspectorate approvals for the design of plates bonded in indent cuts

fGtm mean tensile strength in N/mm2

fGcm mean compressive strength in N/mm2

fGt,i smallest determined tensile strength in N/mm2

fGc,i smallest compressive strength obtained in N/mm2

sGc, sGt standard deviation of compressive and tensile strengths of the adhesive, kn factor according to DIN EN 1990, see Table 3.4

(4) The standard deviation of compressive and tensile strengths of the adhesive shall be obtained as follows:

sGc=√ 1(n−1)∑i=1

n

( f Gc,i− f Gc,m )2

(1)

sGt =√ 1(n−1 )∑i=1

n

( f Gt,i− f Gt,m)2

(2)Table 3.4 values kn

n 6 8 10 20 30 ∞

kn 2.18 2.00 1.92 1.76 1.73 1.64

(5) If the material characteristic used in the stability analysis cannot be achieved, this shall be considered in the subsequent design.

5.4.3 Adhesive bond on pretreated steel (1) To test the adhesion of the adhesive on the primed steel surface at a room temperature of 20°C, a minimum of three test pieces of 20 mm in shall be glued to a 15 mm thick steel plate or a steel section of equivalent stiffness and pulled off. The characteristic adhesive pull strength fKt,k ≥ 12 N/mm2

shall be reached in a test after 7 days.

(2) The steel plate shall be pre-treated in the same manner as the steel tabs (see sections 2.6.2 (3) to (5)).

5.5 Checks after execution

(1) The evenness of the surface-bonded plates or sheets shall be checked immediately upon removal of any supports used. On a test section of 300 mm, the deviation from the flat surface shall not exceed Δh = 1 mm.

(2) One-way curvatures that push plates or sheeting against the concrete are acceptable.

(3) Bonded steel tabs shall be checked for hollow spaces after curing of the adhesive. If there are hollow spaces in the end zone or more than three defective spots in the middle zone, the tab shall be removed. If there are hollow spaces in other zones or less than 3 hollow spaces, they may be filled pressureless with crack filling material on epoxy resin basis in accordance with DIN EN 1504-5 in combination with DIN V 18028 according to the provisions in RiLi SIB.

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(4) The complete embedding of the CFRP plates bonded in indent cuts shall be checked. Areas of the plate with bondless areas of more than 5 % of the plate sectional area shall subsequently be taken into account in the design.

5.6 Corrosion protection work (1) The thickness of the effective corrosion protection on steel parts shall be assessed on the component by non-destructive methods. The provisions of DIN EN ISO 12944-7 shall apply.

107


Annex A Permanent inspection body (normative)

(1) The contractor shall have a permanent inspection body in place in the event of

installation of concretes of monitoring classes 2 and 3; installation of concrete substitution systems for large-scale additions to concretes of monitoring

classes 2 and 3 (definitions in the meaning of DIN 1045-3, Table 3); production of surfaces of parking areas subject to direct traffic including wear layers; reinforcement of components with concrete in accordance with DIN 1045 or shotcrete in

accordance with DIN 18551; manufacture of components with adhesive bond reinforcement; (2) The permanent inspection body shall

be equipped with all equipment and devices to conduct the tests in accordance with Section 1.3. be headed by a skilled individual experienced in concrete technology and the maintenance of

concrete components, who is able to provide verification of advanced knowledge in concrete technology (E-certificate) and knowledge in the areas of protection, repair and reinforcement of components (German designation of certificate: SIVV -Schein).

If the materials inspection body is involved in the assessment of the building material with regard to the reinforcement by adhesive bonding, the representative of the inspection body shall be certified as a qualified manager for bonded component reinforcements in accordance with Annex D by a recognised inspection body.

(3) The contractor or the head of the concrete inspection body are responsible for regular training of their skilled personnel and keeping records of such training.

(4) If a contractor uses an external inspection body, any inspection tasks shall be transferred to the inspection body by written agreement. Such agreement shall have a minimum validity of one year. The contractor may not hire an inspection body that also monitors the manufacturer of the concrete or concrete substitution systems or of which it is financially dependent.

(5) The permanent inspection body has the following tasks:

provide consulting to the contractor and construction sites; perform tests according to Section 3, unless conducted by site personnel; check equipment on site prior to start of the work; continuous checks and advice on processing and after-treatment of concrete or concrete

substitution systems as well as surface protection systems and reinforcement measures in accordance with Paragraph (1). The results of these checks shall be recorded;

assessment and evaluation of the test results in accordance with section 3 and reporting of the results to the contractor and its supervisors;

training of the skilled site personnel.

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Annex B Test methods during execution (normative)(1) The surface of the substrate in the reinforcement zone shall be inspected visually for

defective spots such as pits, burrs and irregularities, loose particles and concrete chipping, especially above the reinforcement;

moisture, efflorescence, crystallisation, or growth; contamination by foreign materials, e.g. oil, grease, old coatings. (2) Hollow spots near the surface may be detected by differences in sound obtained by tapping.

(3) The test of the substrate moisture content is qualitative according to RiLi SIB with classification of moisture states as “dry”, “moist” and “wet”. The quantitative determination of the concrete’s moisture content may be carried out with the CM devices and assessed in accordance with RiLi SIB. Other test methods for determining the moisture content of concrete are permissible, provided their results are of equivalent relevance.

(4) Determination of substrate roughness shall be carried out in accordance with DIN EN 1766, using the Kaufmann method of measurement.

(5) The surface tensile strength of the substrate and the bond strength between the substrate and individual layers shall be determined in accordance with DIN EN 1542. The test locations shall be predrilled to reach into the substrate.

(6) Cracks that might result in corrosion of existing steel reinforcements shall be recorded in accordance with RiLi SIB.

(7) Measurement of air temperature and humidity as well as surface temperature and determination of dew point temperature shall be carried out in accordance with RiLi SIB.

109


Annex C Supervision of work by an accredited inspection body (normative)(1) The execution of the levelling layers and adhesive work governed by this Guideline are stability-relevant measures. In addition to a monitoring duty of the contractor, there exists a monitoring duty for the inspection bodies listed in the “Verzeichnis der Prüf-, Überwachungs- und Zertifizierungsstellen nach den Landesbauordnungen”, [Listing of testing, monitoring and certification bodies according to state construction regulations, Part V, No 7].

(2) The provisions of this Guideline and DAfStb Guideline ‘Protection and repair of concrete components’, Part 3 shall apply to the monitoring and execution.

(3) The following documentation shall be made available to the inspection body upon request:

planner and auditor of the static analysis; test results on the actual condition of the component to be reinforced; daily reports on reinforcement; delivery notes for products used (adhesive, primer, repair mortar, plates); contractor’s qualification certificates (suitability certificate, ‘SIVV-Schein’); layout plan and properties of the bonded CFRP plates and CF sheeting; results of execution monitoring (see Section Error: Reference source not found).

110


Annex D Certificate of suitability for contractors for reinforcement of concrete components using adhesive bonding (normative)

D.1 General (1) Any contractor that executes component reinforcements according to this Guideline shall provide proof of its qualification in the form of a certificate of suitability for reinforcement of components using adhesive bonding.

(2) Certificates of suitability are granted by certified inspection bodies listed in the Annex to this Guideline. Certificates of suitability may be granted for

reinforcement of CFRP plates and steel tabs by bonding to a component surface (see Section D 3.1);

reinforcement using CFRP plates and steel tabs by gluing them on the component surface or gluing CFRP plates into indent cuts (see Section D 3.2);

reinforcement through lamination of CF sheeting to the component surface for confinement purposes (see Section D 3.3);

reinforcement through lamination of CF sheeting to the component surface for flexural tensile reinforcement (see Section D 3.4).

(3) The suitability test includes the initial inspection of the operation and its skilled personnel in practical suitability tests including monitoring by an accredited inspection body1. The suitability certifications are deemed satisfied if the organisation submits the certificate issued by the inspection body on its suitability for reinforcement of concrete components, where the certificate applies to the respective type of adhesive bonding (see (2)).

(4) Certificates issued prior to entry into force of this Guideline shall be recognised.

D.2 Formal requirements for the operation and the skilled personnel (1) The initial test by the inspection body shall assess whether the personnel and technical conditions for proper reinforcement and their monitoring have been satisfied.

2) The operation shall have on staff a qualified manager in accordance with DAfStb Guideline ‘Protection and repair of concrete components’, Part 3, possessing special knowledge in the area of testing, processing and repair of concrete components and the use of resin products for loadbearing adhesive bonding.

(3) Only skilled site personnel possessing special knowledge and skills in the area of repair of reinforced concrete components in accordance with DAfStb Guideline ‘Protection and repair of concrete components’, Part 3, may take part in the suitability test; they shall demonstrate their skills in

substrate priming; corrosion protection of the reinforcement; use of repair concretes and mortars; filling of cracks; use of adhesives and reinforcement elements in concrete construction. (4) The basic capability to work in accordance with general building inspectorate approvals shall be furnished as proof to the inspection body by means of the respective certificate. This evidence may be furnished in the form of a certificate for “using plastics in concrete construction” [“Verarbeiten von Kunststoffen im Betonbau” (SIVV-Schein)] from Deutscher Beton und Bautechnik-Verein e. V.

(5) The company shall provide evidence that the skilled personnel is trained at intervals of no more than three years on protection and repair measures, especially reinforcement measures using adhesive bonding, in accordance with valid general building inspectorate approvals to enable them to safely carry out proper execution of adhesive work including the necessary tests.

1 See Part IV of the directory of testing, monitoring and certification bodies according to state construction regulations, No 8, last: “Mitteilungen des Deutschen Institut für Bautechnik 41 (2010), Sonderheft 40”

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(6) During the initial assessment of the organisation, the inspection body will evaluate the completeness and status of the test and measuring equipment as well as tools and mixing devices that are necessary for work according to general building inspectorate approvals. The inspection body will review the contractor’s monitoring process for completeness and satisfaction of requirements of general building inspectorate approvals.

(7) The relevant instruments for determining the adhesive pull strength are subject to regular function and accuracy inspections. The results of these inspections shall be documented.

D.3 Suitability tests D 3.1 General requirements (1) The characteristic values obtained during the following suitability tests shall be documented and statistically analysed in accordance with specifications of a valid general building inspectorate approval by the contractor or the material inspection body.

(2) The adhesive bond shall be executed taking into account this Guideline and the execution-relevant sections of a valid general building inspectorate approval. The monitoring report of the contractor and the records of the personnel performing the work shall be checked.

(3) Suitability shall be recognised if flawless adhesive bonds and relevant results in accordance with a valid general building inspectorate approval have been achieved. The suitability tests may only be repeated in their entirety per reinforcement type.

D 3.2 Reinforcement by bonding CFRP plates and steel tabs to the component surface (1) For reinforcement using CFRP plates and steel tabs bonded to the surface of a component, a reinforced concrete beam made from C 30/37, 4 m in length and minimum 400 mm in height shall be reinforced at a height of 3 m. Substrate priming for adhesive bonding shall be conducted in line with the execution-relevant sections of a general building inspectorate approval for surface-bonded CFRP plates and this Guideline. The monitoring report of the contractor and the records of the personnel performing the work shall be checked.

(2) Two steel tabs and two CFRP plates as longitudinal tensile strength reinforcement shall be bonded to the bottom side of the reinforced concrete beam located at 3 m height. Additionally, 2 steel tab links consisting of two L-shaped parts shall provide the shear reinforcement. Of the two steel tabs for longitudinal reinforcement, one should be dimensioned 100 mm x 10 mm x 3 500 mm and the other 200 mm x 10 mm x 3 500 mm. The CFRP plates for longitudinal reinforcement shall be different in width and 3 500 mm long. The width of the steel tabs for shear reinforcement shall be 100 mm. The leg length of the two L-shaped parts shall be selected so that in the bonded state, they will enclose the beam width and height of the concrete beam to be reinforced.

(3) Prior to applying the wider steel tab and the wider CFRP plate for longitudinal reinforcement, the concrete cover shall be chiselled down to the reinforcement in the mid zone of the adhesion surface to create a defective spot. The defective spot shall be repaired using reprofiling mortar in accordance with Section 2.5 of this Guideline.

(4) Upon curing of the adhesive, the steel tab links and then the steel tabs for longitudinal reinforcement shall be pried off. The adhesive bond shall then be assessed. There should be complete concrete failure in the areas bonded to the concrete, both in the steel tab link and the steel tabs for longitudinal reinforcement.

(5) The evaluation of the bond of the CFRP plates for longitudinal reinforcement shall be conducted after curing of the adhesive by means of pull-off tests. Prior to the pull-off test, snap ring grooves with an inner diameter of 50 mm or square grooves of 50 mm side length shall be drilled or cut into the concrete, or the plate shall be cut cross-wise at a width that is equivalent to the diameter of the test piece. The test pieces shall be glued to the CFRP plates inside the grooves or the cut joint. Five pull-off tests shall be conducted, with a minimum of 2 tests on each CFRP plate. Here the concrete failure shall be complete.

D 3.3 Reinforcement by bonding CFRP plates, steel tabs to the component surface and by CFRP plates bonded in indent cuts (1) The following assessment shall be furnished in addition to the assessments in D 3.1.

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(2) A reinforced concrete slab located at a height of 3 m or a reinforced concrete beam located at a height of 3 m that is at least 4 m long can be a component for longitudinal reinforcement with CFRP plates bonded in indent cuts. In both cases, the concrete strength class shall be C30/37. For this, 2 indents are cut and 2 CFRP plates glued into them. The minimum length of the CFRP plates shall be 3500 mm.

(3) Prior to cutting the indents in the concrete cover of the reinforced concrete part, a baseline measurement of reinforcement on the entire area to be reinforced shall be conducted by a non-destructive method. All measurements shall be conducted in accordance with the Annex to DBF Code: “Concrete Cover and Reinforcement” [German designation: DBV-Merkblatt “Betondeckung und Bewehrung”] The measuring results shall be checked by exposing the reinforcement in at least one spot.

D 3.4 Reinforcement by laminating CF sheeting to the component surface for confinement (1) For reinforcement using CF sheeting bonded to the surface of a component, a reinforced concrete beam made from C 30/37, 4 m in length and minimum 400 mm in height with shear reinforcement and two well rings with a minimum diameter of 1.5 m and 40 cm height shall be reinforced. If suitability tests in accordance with 3.1 were conducted before, the beams mentioned under 3.1 may be used again for shear reinforcement. All bonded CFRP plates or steel tabs shall first be removed. Substrate priming for lamination shall be carried out in accordance with the respective sections of a valid general building inspectorate approval for reinforcement by laminating CFRP plates onto a component surface and this Guideline. The monitoring report of the contractor and the records of the personnel performing the work shall be checked.

(2) Two strips of the sheeting shall be laminated as shear reinforcement onto the reinforced concrete beam that is located at a height of 3 m. One of the shear reinforcement strips shall consist of one layer and the other of three layers. The width of the shear reinforcement shall be 100 mm. The shear reinforcement shall enclose the entire beam. The well rings shall be wrapped in sheeting strips over their entire height. One well ring shall be covered with one layer of sheeting and the second one with three layers of sheeting.

(3) Prior to laminating, the concrete cover in the lower mid area of the adhesive surface of a shear reinforcement and midway on the well rings shall be chiselled away down to the reinforcement to create defective spots. The defective spots shall be repaired using reprofiling mortar in accordance with section 2.5 of this Guideline.

(4) The assessment of the adhesive bond of the CFRP sheeting shall be conducted by pull-off tests after curing of the laminating resin. Prior to the pull-off test, snap ring grooves with an inner diameter of 50 mm shall be drilled into the CFRP sheeting or square grooves of 50 mm side length shall be cut into the concrete. The test pieces shall be glued to the CF sheeting inside the groove. Five pull-off tests shall be conducted, with a minimum of one test on each CFRP sheet (shear reinforcement and confinement layers). Here the concrete failure shall be complete.

D 3.5 Reinforcement by laminating CF sheeting to the component surface for flexural tensile reinforcement (1) For reinforcement using CF sheeting bonded to the surface of a component, a reinforced concrete beam made from C 30/37, 4 m in length and minimum 400 mm in height shall be reinforced at a height of 3 m. If suitability tests according to 3.1 were conducted, the beams may be used again. All bonded CFRP plates or steel tabs shall first be removed. Substrate priming for lamination shall be carried out in accordance with the respective sections of a valid general building inspectorate approval for reinforcement by laminating CFRP plates onto a component surface and this Guideline. The monitoring report of the contractor and the records of the personnel performing the work shall be checked.

(2) Two sheeting strips as longitudinal reinforcement and two sheeting strips as shear reinforcement shall be laminated to the bottom side of the reinforced concrete beam located at 3 m height. One of each strip, both for longitudinal and shear reinforcement, shall consist of one layer and the other of three layers. The longitudinal reinforcements shall be different in width and 3 500 mm long. The width of the shear reinforcement shall be 100 mm. The shear reinforcement shall enclose the entire beam.

(3) Prior to laminating, the concrete cover in the lower mid area of the adhesive surface shall be chiselled away down to the reinforcement to create defective spots.

(4) The assessment of the adhesive bond of the CFRP sheeting shall be conducted by pull-off tests after curing of the laminating resin. Prior to the pull-off test, snap ring grooves with an inner diameter

113


of 50 mm shall be drilled or square grooves of 50 mm side length shall be cut into the concrete. The test pieces shall be glued to the CF sheeting inside the groove. Five pull-off tests shall be conducted, with a minimum of one test on each CFRP sheet (longitudinal and shear reinforcement). Here the concrete failure shall be complete.

D.4 Certification of the contractor(1) The inspection body shall issue a certificate of suitability for the contractor if proof of suitability has been furnished. A copy of this certificate and the corresponding evaluation reports shall be sent to the German Institute of Structural Engineering.

(2) The certificate is issued for a period of three years and is revocable. Upon request, the validity period of the certificated may be renewed for three years. Prior to each renewal, it shall be demonstrated to the inspection body that the conditions of the general building inspectorate approvals have been satisfied. The contractor shall report any changes in personnel responsible to the inspection body.

(3) Upon expiry of the certification period, the inspection body may extend the suitability certificate. To do so, the contractor shall submit a list of construction projects carried out, including the following information:

Name, location and type of construction project; Supervision report on the execution by the inspection body.

114



Part 4: Additional rules for planning reinforcement measures

Draft March 2012



Published by:Deutscher Ausschuss für Stahlbeton e. V. (DAfStb) Budapester Straße 31D – 10787 Berlin-TiergartenPhone: 030 [email protected]


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DAfStb Guideline on the reinforcement of concrete parts with adhesive bonding – Part 4: Additional rules for planning reinforcement measures

Contents List Part 41 Scope of application...........................................................................................1172 Normative references..........................................................................................1173 Requirements of the component to be reinforced.............................................117

3.1 Special regulations for steel tabs, CFRP plates and CF sheeting bonded to a surface......................................................................................................................117

3.2 Special rules for CFRP plates bonded in indent cuts..........................................117

4 Principles.............................................................................................................1184.1 General......................................................................................................................118

Annex A Determination of the expected mean value..........................................119

116


1 Scope of application(1) This part of the Guideline establishes rules for the planning of reinforcement measures of parts using adhesive bonding.

(2) If repair of a component is necessary as part of a reinforcement measure, the DAfStb Repair Guideline shall also apply.

(3) Application of this Guideline in areas subject to building inspectorate approval shall require a general building inspectorate approval as usability verification of the reinforcement systems.

(4) Planning of reinforcement measures includes an assessment of the actual state.

(5) Prior to start of the measures, satisfaction of requirements on the component to be reinforced shall be examined and documented.

(6) If concrete covers in accordance with DIN EN 1992-1-1 for inner reinforcement are not satisfied, additional measures may be necessary to ensure endurance, taking account the residual life span.

2 Normative referencesDIN EN 1542, Products and systems for the protection and repair of concrete structures – Test methods – Measurement of bond strength by pull-off

DIN EN 1992-1-1, Eurocode 2: Design of concrete structures - Part 1-1: General – Common rules for building and civil engineering structures

DIN EN 13791, Assessment of in-situ compressive strength in structures and precast concrete components

DAfStb Guideline ‘Protection and repair of concrete components’ (‘Schutz und Instandsetzung von Betonbauteilen’), 2001 edition


3 Requirements of the component to be reinforced

3.1 Special regulations for steel tabs, CFRP plates and CF sheeting bonded to a surface

(1) The necessary surface tensile strength of the concrete in accordance with Part 1 of this Guideline shall be determined on the component.

(2) Flatness characteristics shall be checked on the component.

(3) It shall be checked that there is no concave curvature in the area of the planned adhesive bond area. The primed substrate shall not exceed tolerances of 5 mm per 2 000 mm.

(4) In the adhesive bond area, the minimum concrete cover of the steel reinforcement shall be 10 mm to ensure transmission of the bond forces of the adhesive bond.

3.2 Special rules for CFRP plates bonded in indent cuts (1) Large-area unevenness up to 30 mm shall be levelled by grinding or a suitable mortar system.

(2) An analysis of the concrete cover in the area of the plates to be bonded in indent cuts shall be conducted and the results documented. The assessed concrete cover shall at minimum equal the plate width increased by the allowance in design for deviation (see detailing arrangements in Part 1 of this Guideline).

117


4 Principles

4.1 General (1) Planning according to this Guideline shall entail at minimum:

Determination and assessment of the condition of the component to be reinforced (actual state, possibly cause of damage and prognosis).

Assessment of the structural safety including statement regarding stability, serviceability, durability and fire protection;

Statements on the accessibility of the components to be reinforced; Definition whether the reinforcement measure is relevant to stability or for the purpose of

serviceability; Statements on expected future corrosion on the inner reinforcement during the residual life span

of the component in the area of the bonded reinforcement; Specification of potential additional protective measures; Specification of potentially required maintenance and repair after reinforcement of a component; Structural analysis of the reinforcement in accordance with Part 1 of this Guideline; A layout plan with specification of the properties of the adhesive system. (2) Data on the properties of the concrete component to be reinforced originating from existing documentation may be used upon expert evaluation in the planning draft. (3) Data on the actual state of the component to be reinforced required for further planning of the reinforcement measure shall entail the following:

the mean surface tensile strength of the concrete in the bonded areas, determined in accordance with DIN EN 1542. The mean value fctm,surf used in design shall not exceed the expected mean value obtained on the component. The expected mean value shall be obtained as a function of the number of random samples and the standard deviation according to Annex A.

The concrete compressive strength of each component section to be reinforced, determined according to DIN EN 13791;

type and condition of the existing reinforcement; concrete cover of the existing reinforcement and carbonation depth in the concrete; location, course and width of cracks, if these might cause corrosion on the inner reinforcement; if applicable, data on harmful substances in the concrete that might cause corrosion of the

reinforcement or concrete; (4) If the concrete cover of the existing inner reinforcement does not satisfy the requirements of DIN EN 1992, additional measures for ensuring corrosion and fire protection before or after carrying out the bonding work shall be planned.

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Annex A Determination of the expected mean value

(1) The expected mean value shall be determined based on the number of tests and the standard deviation in accordance with Equation (A.1).

f m=( 1n⋅∑i=1

n

f i)−k⋅s(A.

204)Where:

fm expected mean value n number of random samples fi value of individual random samples k value according to Table A.1s standard deviation of the random samples

Table A.10: Factor k

Column 1 2Line n k

1 5 0.9532 6 0.8233 7 0.7344 8 0.6705 9 0.6206 10 0.5807 15 0.4558 20 0.3879 25 0.34210 30 0.31011 35 0.28612

k=tn−1;1− S;

√nCalculated for one side for statistical confidence of S

= 95 %; t from student distribution

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