bridge design w ecs raoul 20121002-ispra

7/24/2019 Bridge Design w ECs RAOUL 20121002-Ispra

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Seminar Bridge Design with Eurocodes JRC Ispra, 1-2 October 2012 1

Design of steel and composite bridgesHighway bridges

Jol Raoul


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Main selected features

General presentation and scope of EC3 and

EC4 related to steel and composite bridges Materials

Structural analysis

Cross-section analysis at ULS and SLS

Treatment of instabilities

Fatigue


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applications

Partie

2

bridges

Partie

7.1

pylons

Partie7.2

chimneys

Partie 6

Cranes

Partie

4.2

tanks

Partie

4.3

Pipelines

Partie

5

piling

Partie

1.1General rules

Partie1.2

fire

Partie

1.3sheetings

Partie

1.4Stainless steel

Partie

1.5Plated

elements

Partie

1.6shells

Partie

1.7

Plated elements

loaded transv.

Partie1.8 joints

Partie

1.9Fatigue

Partie

1.10Brittle

fracturePartie

1.11cables

Partie

4.1

Silos

generic

rules

Partie

1.12 S500 to S690

Eurocode 3 : steel structures


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EN 1994 : composite steel-concrete structures

EN 1994-2 general rules and bridges(self-sufficient)

CONCRETE PART

EN 1992-2

STEEL PART

EN 1993-2


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Scope of EN1993-2

All steel bridges (in general with an orthotropic deck) and the

steel part of composite bridges


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Scope of EN1994-2Composite bridges


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Girder bridges

Economy : two-girderbridges even for 2X2 lanes

due to robustness rules


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Box girders


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Composite members


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Tension members (tie of bowstring arch)


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Composite plates


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Filler beam decks

In the transversal direction In the longitudinal direction


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Materials

Concrete :

Between C20 and C60 for composite bridges (C 90 for concrete bridges)

Steel :

up to S460 for steel and composite bridges(S 500 to S 700 in a separate part 1-12 for steel bridges)


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Choice of material :

avoid brittle behaviour

HOAN BRIDGE 2000


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An overlooked defect is assumed during execution :e.g. : a = 2.2 mm for tf=80 mm

It grows acc. to fracture mechanics laws (assumingfatigue is governing the design)

Up to the critical defectdepending on Charpy energyat service temperature

Over a period dependingon the inspection periodicity

NOTE: fabrication rules andquality plan are given in EN 1090They are assumedto be met when using EN 1993


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EN1

0025

grade quality


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Structural analysis

Elastic

Plastic (buildings, bridges in accidental situations)


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Classes of steel cross-sections

Cl.1

Cl.2Cl.3

Cl.4

Mpl

Mel

1 3 6


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Class offlanges


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Global analysis of composite bridges:

two aspects are considered

Cracking of concrete on

support

Mel,Rd

Mpl,Rd

Class 1

Non linear behaviour at

mid span


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Modular ratio used in a composite section

L 0 L tn n . 1

a0

cm

En

E t 0t t creep coefficient given by EC2 :and

Value of t0: t0= 1 day for shrinkage

t0= a mean value in case of concrete cast in several stages

SIMPLE CALCULATIONS

L is given by :

Permanent loads

shrinkage

Imposed deformations

1,1

0,55

1,5


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Plate buckling and shear lag

Effectivep width

(plate buckling)

effectiveswidth

(shear lag)


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Effectives

width of concrete slab (ULS and SLS)

b1 b1 b2

be1 be2beffb0

eei i

L

b min( ; b )8


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0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

1.2

b0/Le1/50

Shear lag at ULS:

3 alternatives, black

one recommended

Shear lag at SLS:

elastic (red line)

Effectiveswidth of stiffened plates


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Composite cross-section verification at ULS (M>0)

PNA

ENA

Elastic resistance

(for class 1, 2, 3)

plastic resistance

(for classes 1/2)

0,85 fck/gcfck/gc

fy/gM fy/gM

compression

traction

NOTE : gMis 1.0 (recommended for resistance formulae)


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Verification at SLS

Limitation of stresses for steel and composite bridges

As in EN1992-2 and EN1993-2 (fyin the steel part) Limitation of crack widths for composite bridges

As in EN1992-2 with tension stiffening (wk=0.3mm in

general)

Using a simplified method


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exprimental behaviour mechanical model

M

V

P

Aeff

12=-cr

Treatment of instabilities


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Principle of verification

)( fTest /theory

(mechanical

model)calibration

uRk PP PRd=PRk/gM

NOTE : gMis 1.1 (recommended for stability formulae)

cr

u

cr = critical loading / ULS loading

= ultimate loading (without instability)/ ULS loadingu


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Plate buckling of stiffened plates in EC3


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Fatigue verification in EC3

Calculation of DE,2under a fatigue loading

Influence of the type of influence line Influence of the type of traffic Influence of the number of lanes

P = 480kN


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verificationpartial factor forloading= 1,0

Category of

detail

Dc=80


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Orthotropic decks : recommended detailing

Deck plate thickness in the carriage way

in the heavy vehicle lane

t 14 mm for asphalt layer 70 mm


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1st bridge entirelydesigned to EC4 in

Avignon

4500 t

SETRA

SETRA


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Outstanding composite bridges

Max span 144 m: Verrires viaduct (composite box-girder bridge)

Surface > 20000 m: Vzre viaduct

SETRA

SETRA SETRA

Max S460 thickness 120 mm: Guarrigue viaduct


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SOME INNOVATIONS / ECONOMY ISSUES

Enormous scientific work Simplicity of calculations Robustness (fatigue + brittle fracture) Full exploitation of the materials (postcritical range) Steels up to S690 Hybrid girders

Harmonization of the format and the reliability of allthe instability formulae

Treatment of stiffened plates Design of orthotropic decks

bridge design w ecs raoul 20121002-ispra

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