ple-02 vsl brian lim

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PRESTRESSED CONCRETE DESIGN AND CONSTRUCTION: A STATE OF THE ART REPORTASEP SUMMIT 2012JUNE 08‐09, 2012

BRIAN LIMBRIAN LIMSENIOR BUSINESS DEVELOPMENT MANAGER SENIOR BUSINESS DEVELOPMENT MANAGER VSL HONG KONG LIMITEDVSL HONG KONG LIMITED

ASEP SUMMIT 2012June 08-09, 2012Regalia Tower Hotel Suites, Cubao, Quezon City

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OBJECTIVES

Recent developments in national codes, construction material and emphasis on sustainable construction, have led to a significant departure in the way we design and construct prestressed concrete structures.

In this paper, a state of the art prestressed concrete design and construction of buildings, bridges and special structures will be examined.


Gateway Bridge, Australia

Structural concrete has seen an extraordinary development and has become the material of choice for structures.Significant progress through continuous innovation


GBS Platform, North Sea PT floors, Chile

Success factors for concrete:‐ Local availability of concrete materials‐ Development of specific construction methods &specialised equipment‐ Improved knowledge in design of structural concrete ‐ Availability of modern post‐tensioning technology

LNG Tank, Spain


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1. Systems2. Buildings3. Bridges4. Other Applications5. New Developments and Applications

PRESTRESSED CONCRETE


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Strand Type:

Systems:


Tendon Arrangement:

Systems:


Stressing Anchorages:

Type CS Type SC

Systems:


Stressing Anchorages: Type GC

• ETAG013 Compliant for Static Load Test, Load Transfer Test and Fatigue Test.

• Will be approved by HK Highways this year.

• Replaces Type Sc, which complies to the superseded BS4447

Systems:


Type KC

Coupling Anchorages:

Systems:


Type P

Non‐Stressing Anchorages:

Type H

Type AF

Systems:


Sheathing:

Systems:


Systems:


Type S


Type VSLAB

S Series

S6‐1

S6‐2

S6‐3

S6‐4

S6‐5

Systems:


Type Bondtech Type S5‐2 S5‐1, S6‐1


Systems:


Type SK Type H

Other Anchorages:

Systems:


Individual Strand Stressing

Systems:


Multi‐Strand Stressing

Systems:


Systems:

Cable Stay System & Dampers


Cable Stays SSI2000:

Systems:


Cable Stays SSI2000:

Systems:


Cable Stay Anchorages:

Systems:


Cable Stay Damper Assembly

Deck connector

Anti‐Vandalism Pipe(AVP)

Gensui Pad

Guide Pipe(GP)

GP bracket

Damper Support(DS)

Cable flange

Systems:


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1. Systems2. Buildings3. Bridges4. Other Structures5. New Developments

and Applications

Buildings:


Examples of:

Long Span Structures

Grade A Offices

Commercial Buildings

Transfer Beams & Plates

Buildings:


Hang Seng Bank: PT Beams & RC Slab

Buildings:


900mm deep PT beams spanning 29.0m

Buildings:


During construction Completed

Buildings:


Gateway II: Artist’s impression

Buildings:


10~12m span, 260mm flat slab w/ drops

Buildings:


Typical floor tendon layout

Buildings:


Large cantilever span – 4.5m

Buildings:


Three towers constructed at the same time

Buildings:


Gateway II Completed

Buildings:


One Island East

Buildings:


Variable Floor Outline

Buildings:


Buildings:


Typical Floor PT Layout

Buildings:


Concreting in progress

Buildings:


One Island East:

• 70 storey building (60PT)

• 2,000m2 per floor

• 4/5‐day cycle

• Use of

– VSL Climbform

– Mini tables and

– Safety screens

Buildings:


Buildings:


Macao Yaohan: PT band beams with 230mm slab

Buildings:


During Construction Completed

Buildings:


Artist’s Impression

Venetian Cotai, Macau, Parcel 1

Buildings:


Artist’s Impression

Buildings:


Precast Construction: 20 x 20 m bay

Buildings:


Example: Level 3 (20 x 20 m Grid)

Buildings:


During Construction

Buildings:


Completed (Right)

Buildings:


Transfer Beams

Festival Walk, Kowloon Tong

Buildings:


PT Transfer Beams: 4.5m deep x 46m span

Buildings:


Transfer Plates

• Transfer of high concentrated forces

• Thick plates or beams with high rebar content

• Shear Controlled

Buildings:


Arrangement of Load Bearing Wall & Columns

Buildings:


Layered Construction

Stage 1: Casting 1st layer (~ 1/3 d)Stressing bottom tendons

Stage 2: Casting remaining plate(supported by 1st layer)

Stage 3: Stressing middle and top tendons

Stage 4: Construction of floors above can proceed

Buildings:


0

20

40

60

80

100

120

Concrete Rebars Fmwk Cost

RC

PT

MATERIAL & COST COMPARISONPT VS RC TRANSFER PLATE

Buildings:


Transfer Plates in Hong Kong

0

5

10

15

20

25

30

35

40

45

88-89 90-91 92-93 94-95 96-97 98-99 00-01 02-03 04-05 06-07 08-09 10-11

Year

Nu

mb

er o

f P

late

s

Design

Completed

Buildings:


Concrete

0%

20%

40%

60%

80%

100%

120%

RC PC

Reinforcement

0%

20%

40%

60%

80%

100%

120%

RC PC

PT floors help to reduce material handling and labour

Note: Reductions• Concrete: ‐20%• Reinforcement: ‐ 65%• Labour: ‐ 60% Sustainability

Buildings:


95.3129.9Total CO2 emission

3.00

PT steelRC = 0PC = 5 kg / m2

8.324.8

Reinforcing steelRC = 42 kg / m2

PC = 14 kg / m2

84.0 105.1

Concrete (300kg cement / m3)RC = 0.35 m3 / m2

PC = 0.28 m3 / m2

PC(kg CO2 / m

2)RC

(kg CO2 / m2)

Materials and quantities

CO2 emission for building floor:

PT offers 27% reduction in CO2 emission in floors!

Buildings:


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Standard Bridges: Cast‐in‐place post‐tensioned box girders

Colorado, USA

Bridges

In‐situ post‐tensioned construction


In‐situ construction (form‐traveller method)

Bridges


In‐situ construction (form‐traveller method)

Bridges


Precast Beam construction (with O/H Gantry)

Bridges


Bridges

Precast Beam construction (with O/H Gantry)


Savings in formwork and scaffolding and improved aesthetics favour precast segmental construction

Precast segmental bridges

Bridges


Balanced cantilever construction (with O/H Gantry)

Span‐by‐span construction (with O/H Gantry)

Bridges


Balanced cantilever construction (with Lifting frames)

Span‐by‐span construction (with crawler cranes)

Bridges



Bridges


Large‐scale projects became feasible through introduction of precast segmental construction

Dallas High Five Interchange, USA


Bridges


West Rail project, Hong Kong 13.5km of viaduct 658 spans of 35 to 44m 9400 segments 3500 t internal pt

From highway applications to light rail applicationsPrecast segmental bridges

Bridges


Avignon viaducts, France 1.5km of twin viaduct Spans of 100m and 50m Precast segmental deck Internal and external pt

…. to high-speed rail bridge applicationsPrecast segmental bridges

Bridges


Cable Stays for all Climatic Conditions

Cable stay bridges

Bridges


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1. Systems2. Buildings3. Bridges4. Other Structures5. New Developments and Applications



Union Square, Hong Kong

PT Transfer Plates

PT Out‐Rigger

VSL AF6‐31

Other Applications:


ELEVATIONPLAN

International Commerce Center (ICC), Hong Kong

Prestressed Out-Riggers

Other Applications:


IR Sands, Singapore

Vertical Prestressing

Other Applications:


34 storey leaning tower (18 degrees). Vertical tendons in building core to control leaning of tower (> tower of Pisa).

ABU DHABI, Capital Gate Tower


Other Applications:


Harbour Side, Union Square K11, Hanoi Road, TST


Other Applications:


Cable‐Stayed Roof

Alamo Dome StadiumTexas, USA

Borlmage, Sweden

Other Applications:


Thermal Storage Reservoir (14m high x 33m dia)Texas, USA

Silos and Tanks

Other Applications:


Monostrand post‐tensioning for roof (33 m diameter)

Silos and Tanks

Other Applications:


Horizontal & vertical prestressing in walls (355 mm thick)

Silos and Tanks

Other Applications:


Egg‐Shaped Digestors, Singapore

Silos and Tanks

Other Applications:


Circumferential Prestressing

Silos and Tanks

Other Applications:


Omeshi Nuclear Plant, Kansai Electric Power, Japan

Nuclear Containment Vessel (PCCV)

Other Applications:


Off‐Shore Structures

Olje Hedrun GBS

Other Applications:


Skirts and lower domes under construction in dry dock.

Troll Gravity Base Offshore Platform


Other Applications:


Platform legs completed and ready to being sunk and towed out


Other Applications:


Dimensions : 220 m x 46 m x 16 mDisplacement : 107,000 tons

N’KOSSA‐CONGO Barge


Other Applications:




Other Applications:


Quantities: 26,400 m3 HPC,4,700 tons Reinf2,700 tons PT



Other Applications:


N’KOSSA‐CONGO Barge – towed out


Other Applications:


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1. Systems2. Buildings3. Bridges4. Other Structures5. New Developments and Applications



CONTENTS:

(1)MATERIALS

Concrete

(2)TECHNOLOGIES

PT SYSTEMS

DAMPING DEVICES

New Developments and Applications


Strength of construction materials has evolved over last 20‐30 years, mainly for concrete

N.B.: Prestressing steel may see increase to 2160MPa soon

Evolution of material strengths

0

500

1000

1500

2000

Structural steel Reinforcing steel Prestressing steel Concrete

Str

en

gth

s (

MP

a)

1980

2000

30200



Development of:

High‐Strength, High‐Performance Concrete

Ultra‐High Strength Fibre Reinforced Concrete (UHPC) very low water content, small aggregates with high packing density, large amounts of relatively short fibres (≥ 2% of volume, 10‐20mm long)



Ductal®-FM 300 MPa 150 - 180 MPa

Maximum Charact ValueCompressive strength

0

20

40

60

80

100

120

140

160

180

200

220

0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 2

Strain in %

Com

pres

sive

str

ess

in M

Pa

Ordinary concrete

Ductal

Compression test

®



Porosity

Low total porosity in range of nano-meters (10-9 m)

Cu

mu

late

d p

oro

sity

of

the

ma

trix

(in

%)

Diameter of pores (nm)

1 10 100 1µm2 3 5 20 50 200

Micro-pores Capillary

C30

C60

C100FSDuctal®

50

40

30

20

10

0


Applications – Pedestrian bridges

Seonyu / Seoul, Korea

Sherbrooke, Canada Auckland, New Zealand

Sakata Mirai, Japan



Several highway bridges were built in Australia, Japan, France, USA

GSE Bridge, Haneda Airport Tokyo (2008)

Shepherds Creek bridge, Australia (2004)


Applications – Highway bridges


• Haneda International Airport extension, Tokyo Japan

• One third of runway is built on steel jackets with composite

steel‐concrete deck made of HPC and UHPC precast panels

Durability & 55% weight saving the winning UHPC arguments

Applications – Haneda International Airport, Tokyo



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• Fabrication 7000 pretensionedslabs; size 3.8 x 7.8m, total 22’000m3

• 55% weight savings due to use of Ductal®

Applications – Haneda International Airport, Tokyo



Applications – Protection

UHPC panels as linings to protect pile caps, exposed areas of piers, and tunnels(examples from Japan)



CONTENTS:

(1)MATERIALS

Concrete

(2)TECHNOLOGIES

PT SYSTEMS

DAMPING DEVICES



Approval of PT systems (ETA)

European Approval and Certification scheme ensure that all systems offered on market satisfy essential criteria specified in ETAG013 and have continuous surveillance (FPC and independent audits)

Initial assessment and approval of PT system

by AB

Attestation of

Conformityby CB

Continuous Surveillance(FPC and

control by CB)

Renewal of Certificate of Conformity after 5 years

This concept is considered preferrable over project specific assessment by engineerRef: Guideline for European Technical Approval of PT Kits (ETAG013)




Qualification of PT company and personnel

PT works shall be carried out by PT specialist companies who have qualified and trained personnel and supervisors / managers Ref: CWA 14646, FIP Recommendations (1996)



Corrosion protection of tendons must be a key consideration in design of any PT structure

fib/IABSE workshops in Ghent and Zurich

fib Bulletin 33 provides recommendations for corrosion protection of tendons

Ynys‐Y‐Gwas Ynys‐Y‐Gwas

Corrosion protection



Main problem is access of water with chlorides from the outside into the tendon (or water only if not fully grouted)

Hence, provide leak tight encapsulation to avoid ingress of water and chlorides where applicable

Problem: Access of Problem: Access of water to tendonwater to tendon

Grout voids with water: Corrosion Grout voids without water: No corrosion




Proposal of three protection levels for PT tendons adapted to environment/exposure and structural protection : PL1, PL2 or PL3

PL2

PL3

PL1

Lo

wM

ed

ium

Hig

h

Ag

gre

ssiv

ity

/ E

xp

os

ure

LowMediumHighAction

Structural protection layersStructuralProtection




PL 1 PL 2

PL1: A duct and a filling material providing durable corrosion protection (metal duct, cement grout)

PL2: PL1 plus an envelope over full tendon length, leak tight barrier (plastic duct and cap)




Rebar

PL3: PL2 plus integrity of tendon or encapsulation to be monitorable or inspectable at any time (e.g. EIT in acc. with Swiss Guidelines)

PL 3

ASTRA Guideline: Measures to ensure the durability of post-tensioning tendons in structures (2001, 2007)




EIT measuring : Alternating current – resistance measurement High resistance = intact encapsulation




EIT Tendon : Locating of defect with measurement of magnetic field

Sector A Sector B

i

Alternating current

Pavement

DEFECT

246810121416

Length [m]




Grout:

• Corrosion protection of strands.

• Transfer of forces from strands to concrete.



Grout Specifications

≥30MPa≥30MPaStrength at 28 days

Cube or cylinder

(50‐100mm)

≥27MPa≥20MPaStrength at 7 days

Plastic Cylinder (100‐200mm high)

≤ 2%≤ 2%Bleed

Plastic Cylinder (100‐200mm high)

‐1% to +5%‐2% to +5%Volume Change

Flow cone

(Dia 10 or 12.7mm)

≤ 25 sec.Flowability / Fluidity

Test MethodEN447FIP GuideProperty



Standard Grout Tests :

Optimised Grout Common Grout

Standard bleed test is able to identify which grout unstable.

Grout:



Recommended Types of Testing

TESTS REASONS PROCEDURE

Initial testingof grout

confirmnew grout

Common: tests on sitespecial: optimisation

Approval testingof grout

approvenew grout

confirm grout complieswith requirements

Suitability testingof grout

compare testson site

and laboratory

flow time, bleed, shrinkage,expansion, strength

Quality controltest

control grouton site

local standard testsproject specifications

Full scale sitetesting

if requiredno void, no bleed,

no corrosionat high points


Grout:


New Grout Tests :• Wick‐Induced Test• Inclined Tube Test

Common Grout

Optimized Grout


Grout:


Inclined Tube Test:

Common Grout

Optimised Grout


Grout:


Issue of protection of internal tendons in segment joints

Sealing of segment joints withepoxy resin and foam seal

Sealing plastic ducts across segment jointswith leak tight coupling device



Innovative bridge deck structure for span range100‐200 m

Pakse Bridge, Laos (2000):Extradosed tendons exposed similarly to stay cables

Extradosed bridges



Pakse Bridge, Laos (143 m extradosed span)

• Span range: 100 - 200 m• Girder depth at mid span:

Span/55• Girder depth at pier: Span/35• Height of pylon above deck:

span/12• ED tendon stress range: 20 -

50 MPa

Note: Continuous transition from segmental span into extradosed span

Extradosed bridges



Ibigawa/Kisogawa Bridges in Japan Completion 2001 Designer: JBS Inst. Contractors: 4 JVs


Extradosed bridges Extradosed composite bridges with 275 m main spans


Saddle offer simplified detailing of pylon, reduction of pylon dimensions, and savings in overall cost of pylon

Extradosed tendon specification:‐Max tendon stress 60% GUTS‐Max stress range 140MPa

Extradosed bridges



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Cable saddles with improved static, fatigue and friction performance with individual holes for each strand to comply with tendon performance


Cable Saddles


Through continuous innovations in structural concrete: materials, technologies and applications

Structural prestressed concrete will remain a material of choice for structures

Conclusions


Creating

Solutions

Together

The End

ple-02 vsl brian lim

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