bridge design w ecs raoul 20121002-ispra
TRANSCRIPT
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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