FIELD EVALUATIONS OF WATERPROOF MEMBRANE SYSTEMS FOR BRIDGE DECKS
Compressive Membrane Action in Concrete Decks
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Transcript of Compressive Membrane Action in Concrete Decks
1 Titel van de presentatie
Compressive Membrane Action in Concrete Decks
9th fib International PhD Symposium in Civil Engineering
Karlsruhe Institute of Technology (KIT), Germany
Sana Amir 24-07-2012
Prof. Dr. ir. J. C. Walraven, Dr. ir. C. van der Veen
Structural Engineering / Concrete Structures
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Contents
1: Introduction: Compressive Membrane Action
2: CMA in reinforced concrete decks - Flexural load carrying capacity - Punching Shear capacity 3: Application of CMA theories to experimental data 4. CMA in transversely prestressed concrete decks : Investigating Punching Shear capacity 5. Future Tests 6. Conclusions
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Introduction
Compressive Membrane Action
CMA is a phenomenon that occurs in slabs whose edges are restrained against lateral movement by stiff boundary elements. This restraint induces compressive membrane forces in the plane of the slab (Park and Gamble, 1980).
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• Bridges are traditionally designed to carry the wheel load entirely in
flexure.
ASSUMPTION: Adequate shear capacity.
• A bridge deck slab designed for bending tends to fail in the punching
shear mode at a load much higher than that based on flexure.
• Considerable research is done on reinforced decks. Prestressed decks
need to be investigated.
Introduction
Compressive Membrane Action
?
PhD Research
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ka = 8/L and kb = 4/L
CMA in reinforced concrete decks
Flexural Capacity by Rankin and Long
acityArchingCapMarc
acityBendingCapMb
)( barcflx MMkP
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Kirkpatrick, Rankin, Long, Taylor’s Approach
UK HIGHWAY AGENCY STANDARD BD 81/02
/ 0.251.52( ) (100 )p c eP d d f Q
Punching Shear Capacity
/ 2
2320 0.75
ce
kf hQ
d
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• Modified form of Kinnunen – Nylander Model.
Limitation:
Analysis of symmetric punching of reinforced slabs without shear reinforcement – Open to further development.
Punching Shear Capacity
Mikael Hallgren Model
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where Fb = η Fb(max) and Mb = η Mb(max)
Modified Hallgren Model
Punching Shear Capacity
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Capacity predictions for reinforced concrete decks
Tests by Taylor et al (2001)
Application to Experimental Data
Test Panel Pt PBS PBD81
Ptaylor Pmh Pt / PBD81 Pt / Ptaylor
Pt / Pmh
[kN] [kN] [kN]
[kN] [kN]
D1 185 49.4 341.1 191.8 219.8 0.54 0.96 0.84
D2 200 49.3 317.6 181.3 206.8 0.63 1.10 0.97
D5 150 38 268 151.1 164.5 0.56 0.99 0.91
D6 182 38.1 276 173.3 184.12 0.66 1.05 0.99
D7 135 38.1 280.9 92.5 155.29 0.48 1.46 0.87
D8 157 38.7 274 148.9 167.45 0.57 1.05 0.94
Average 0.57 1.10 0.92
St. deviation 0.06 0.18 0.057
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Capacity predictions for reinforced concrete decks
Tests by Kirkpatrick et al (1984)
Application to Experimental Data
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Capacity predictions for reinforced concrete decks
Tests by Taylor et al (2007)
Application to Experimental Data
Test Panel
Deflection
[mm]
Pt
[kN]
PBD81 [kN]
Pmh [kN]
PBS
[kN]
PBD81/PBS
Pmh/PBS
Pt/Pmh
A1 2.5 333 570.1 401 128.3 4.44 6.75 0.83
A2 1.5 428 600.8 426.4 178.3 3.37 5.70 1.00
B1 2.15 344 563.6 381 66.5 8.48 11.07 0.90
B2 1.15 428 610.4 445.2 92.3 6.61 9.60 0.96
C1 2.6 333 588 406 66.6 8.83 11.58 0.82
C2 1.2 428 588 427.5 92.2 6.38 9.24 1.00
D1 1.85 368 553.5 365 127.9 4.33 5.51 1.01
D2 1.75 428 568.3 412 177.3 3.21 5.35 1.04
E1 1.95 392 632.8 484 202.1 3.13 3.89 0.81
E2 1.6 428 648.7 484.7 280 2.32 3.36 0.88
F1 1.9 371 566.5 415 199.5 2.84 3.56 0.89
F2 0.75 428 601.2 464.2 275.2 2.18 3.19 0.92
Average 0.92
St. deviation 0.08
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Prestressed Concrete Decks
• Provisional of additional in-plane forces due to prestressing
• Improved punching shear capacity
• Improved serviceability
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Engineering Method
ps pe
e s
y
f
f
Charts from OHBDC or NZ code may be used to estimate the ultimate capacity.
Analysis Methods
Modified Hallgren Model
where Fb = η Fb(max) and Mb = η Mb(max)
Punching Load
Boundary Lateral Restraint
Prestressing
Method of superposition
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Test Panel
Ap
[mm2]
TPL
[MPa]
Pt
[kN]
Pmh [kN]
PNZ [kN]
Pt/Pmh
Pt/PNZ
SW-1A 0.0869 1.84 53.1 59.77 67.39 0.89 0.79
SE-1B 0.0869 1.84 53.04 59.77 67.39 0.89 0.79
CW-2B 0.105 2.15 54.82 64.16 70.45 0.85 0.78
CE-2B 0.105 2.15 57.26 64.16 70.45 0.89 0.81
NW-2A 0.1198 2.5 63.85 67.57 71.68 0.94 0.89
NW-2B 0.1198 2.5 48.7 67.57 71.68 0.72 0.68
CE-1B 0.14 2.91 74.43 72.08 74.74 1.03 1.00
CW-1A 0.14 2.91 65.82 72.08 74.74 0.91 0.88
SE-2B 0.1549 3.32 66.31 75.42 76.58 0.88 0.87
SW-2A 0.1549 3.32 72.97 75.42 76.58 0.97 0.95
NE-1B 0.176 3.88 80.54 80.15 79.65 1.00 1.01
NW-1A 0.176 3.88 77.52 80.15 79.65 0.97 0.97
CE-1A 0.19 4.37 94.12 83.42 80.87 1.13 1.16
NE-2A 0.19 4.37 92.28 83.42 80.87 1.11 1.14
NW-3B 0.19 4.37 80.11 83.42 80.87 0.96 0.99
CW-4B 0.19 4.37 82.66 83.42 80.87 0.99 1.02
SE-5B 0.19 4.37 87.3 83,42 80.87 1.05 1.08
SW-6A 0.19 4.37 92.23 83.42 80.87 1.11 1.14
Average
0.96 0.94
St. deviation
0.10 0.14
Tests in Queen’s University, Kingston, Canada
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Savides (1989), He (1992)
Tests in Queen’s University, Kingston, Canada
• Prestressing postpones the commencement of lateral movements, delays cracking.
•Lesser the lateral movement possible, higher is the level of CMA leading to higher
punching loads.
40
50
60
70
80
90
100
0 1 2 3 4 5
Pu
nch
ing L
oad
(k
N)
TPL (MPa)
(TPL ~ Punching Load)
Pt
Pmh
PNZ
Linear (Pt)
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FUTURE TESTS
Transverse Prestress Level
1.25 MPa 2.5 MPa
6400
• Variable TPL
• Joint skewness and roughness
• Variable position/locations of the load
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•The UK Highway Agency BD81/02 gives good results for rigidly restraint deck slabs.
However, when the restraint is low, the results are unsafe. Also, this method does not
allow for the effect of varying reinforcement ratio.
•Taylor’s approach incorporates both flexural punching and shear punching failures.
•The New Zealand code gives better estimation when the TPL is high.
•Modified Hallgren model gives good results both for reinforced and transversely
prestressed deck slabs, therefore it will be used for future tests as well.
• Deck slabs exhibit high punching strength in the presence of CMA resulting from lateral
restraint and transverse prestressing.
•Future Study: Working on a 3D Nonlinear FEM Analysis.
Conclusions & Future Study
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Thank you