My presentation at fib Symposium for Civil Engineering, Karlsruhe 2012.

1. 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 van de presentatie
Titel 1

2. 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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3. 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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4. Introduction
Compressive Membrane Action
• 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.
PhD Research
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5. CMA in reinforced concrete decks
Flexural Capacity by Rankin and Long
Marc  ArchingCap acity
Mb  BendingCap acity
Pflx  k (Marc  Mb)
ka = 8/L and kb = 4/L
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6. Punching Shear Capacity
Kirkpatrick, Rankin, Long, Taylor’s Approach
UK HIGHWAY AGENCY STANDARD BD 81/02
kf c/ h 2
Qe 
320  0.75d 2
Pp  1.52(  d )d f c (100Qe )0.25
/
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7. Punching Shear Capacity
Mikael Hallgren Model • Modified form of Kinnunen – Nylander Model.
Limitation:
Analysis of symmetric punching of reinforced
slabs without shear reinforcement – Open to
further development.
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8. Punching Shear Capacity
Modified Hallgren Model
where Fb = η Fb(max) and Mb = η Mb(max)
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9. Application to Experimental Data
Tests by Taylor et al (2001)
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
Capacity predictions for reinforced concrete decks
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10. Application to Experimental Data
Tests by Kirkpatrick et al (1984)
Capacity predictions for reinforced concrete decks
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11. Application to Experimental Data
Tests by Taylor et al (2007)
Test Panel Deflection Pt PBD81 Pmh PBS PBD81/PBS Pmh/PBS Pt/Pmh
[mm] [kN] [kN] [kN] [kN]
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
Capacity predictions for reinforced concrete decks
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12. Prestressed Concrete Decks
• Provisional of additional in-plane forces due to prestressing
• Improved punching shear capacity
• Improved serviceability
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13. Analysis Methods
Engineering Method Modified Hallgren Model
 ps f pe
e   s 
fy
Charts from OHBDC or NZ code may be
used to estimate the ultimate capacity.
where Fb = η Fb(max) and Mb = η Mb(max)
Method of superposition
Punching Load
Boundary Lateral Prestressing
Restraint
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14. Test Panel Ap TPL Pt Pmh PNZ Pt/Pmh Pt/PNZ
[mm2] [MPa] [kN] [kN] [kN]
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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15. (TPL ~ Punching Load)
100
90 Pt
Punching Load (kN)
Pmh
80
PNZ
70
Linear (Pt)
60
50
40
0 1 2 3 4 5
TPL (MPa)
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.
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16. FUTURE TESTS
• Variable TPL
• Joint skewness and roughness
• Variable position/locations of the load
Transverse Prestress Level
1.25 MPa 2.5 MPa
6400
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17. Titel van de presentatie 17

18. Titel van de presentatie 18

19. Conclusions & Future Study
•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.
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20. Thank you
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