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Punching Shear Strength of Transversely Prestressed Concrete Decks

Sana Amir

04-07-2012

Prof. Dr. ir. J. C. Walraven, Dr. ir. C. van der VeenStructural Engineering / Concrete Structures

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Contents

1: Introduction: Compressive Membrane Action

2: Past Research: Existing methods

3: Punching Shear in Transversely Prestressed Concrete Decks: Analysis methods

4. Future experiments

5. Conclusions

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IntroductionCompressive 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.

• Prestressing provides additional in-plane forces. Therefore, there is a need to investigate the use of transverse prestressing in bridge decks considering CMA.

IntroductionCompressive Membrane Action

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Past Research

Provided the limitations are satisfied, charts from OHBDC (1979), NZ Code can be used for strength assessment.

Kirkpatrick, Rankin, Long, TaylorUK HIGHWAY AGENCY STANDARD BD 81/02

/ 0.251.52( ) (100 )p c eP d d f Q Hewitt & Batchelor Model

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• Modified form of Kinnunen – Nylander Model.

• Difference is in the failure criterion

• Slope of the shear crack is not constant but varies with the geometry and the material properties of the slab.

Mikael Hallgren Model

Limitation:

Analysis of symmetric punching of reinforced slabs without shear reinforcement – Open to further development.

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Punching Shear Failure Transversely 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 pee s

y

f

f

Charts from OHBDC or NZ code may be used to estimate the ultimate capacity.

Analysis MethodsModified Hallgren Model

where Fb = η Fb(max) and Mb = η Mb(max)

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Capacity predictions for reinforced concrete decks by UK Highway BD81/02 and

modified Hallgren model.

Tests by Kirkpatrick et al (1984)

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Application to Experimental Data

R² = 0.8233

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 1 2 3 4 5 6

η

TPL (MPa)

η - TPL relationship

Savides (1989), He (1992)

Tests in Queen’s University, Kingston, Canada

40

50

60

70

80

90

100

0 1 2 3 4 5

Pu

nch

ing

Loa

d (k

N)

TPL (MPa)

TPL ~ Punching Load

Pt

Pmh

Ph&b

PNZ

Variable Restraint Factor

Method of superposition

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FUTURE TESTS

Transverse Prestress Level

1.25 MPa 2.5 MPa

6400

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Main Parameters:

Transverse Prestress Level

Skewness of the joints

Loading position

CMA

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• Deck slabs exhibit high punching strength in the presence of CMA resulting from lateral restraint and transverse prestressing.

• Since the TPL directly determined the degree of CMA, the punching strength is highly dependent on TPL.

• Modified Hallgren model effectively predicts the punching strength of prestressed bridge decks.

• Tests are required on prestressed decks to gain better understanding of the effect of compressive membrane action and transverse prestressing on punching strength.

Conclusions

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REFERENCES Brotchie, J. F. and Holley, M. J. (1971), “Membrane Action in Slabs” ACI Special

Publication, SP – 30, pp 345-377. Hallgren, M. (1996), “Punching Shear Capacity of Reinforced High Strength Concrete

Slabs,”Ph.D Thesis, Royal Institute of Technology, S-11 44 Stockholm, Sweden. Harris, A. J. (1957), Proceedings of Institution of Civil Engineers, V. 6, pp. 45-66. Hewitt, B. E., and Batchelor, B. deV. (1975), “Punching Shear Strength of Restrained Slabs,

ASCE J. of Structural Engineering, V. 101, ST9, pp. 1837-1853. Kinnunen, S., and Nylander, H. (1960), Trans. Royal Inst. Technology, Stockholm, No. 158. Kirkpatrick, J., Rankin, G. I. B., and Long, A. E. (1984), “Strength of Evaluation of M-Beam

Bridge Deck Slabs,” Structural Engineer, V. 62b, No. 3, pp. 60-68. Ockleston, A. J. (1955), “Load Tests on a Three Storey Reinforced Concrete Building in

Johannesburg,” The Structural Engineer, V. 33, pp. 304-322. Ontario Ministry of Transport and Communications: Ontario Highway Bridge Design Code

(OHBDC), (1979, amended 1983 & 1992), Toronto, Ontario. Park, R. and Gamble, P. (1980), “Reinforced Concrete Slabs”, John Wiley & Sons, UK. Rankin, G. I. B. (1982), “Punching failure and compressive membrane action in reinforced

concrete slabs”, Ph.D. Thesis, Department of Civil Engineering, Queen’s University of Belfast.

Rankin, G. I. B. and Long, A. E. (1997), “Arching Action Strength Enhancement in Laterally Restrained Slab Strips,” ICE Proceedings – Struc. & Buildings, No. 122, pp. 46-467.

Savides, P. (1989), “Punching shtength of transeversely prestressed deck slabs of composite I-beam bridges”, M.Sc. Thesis, Queen’s University Kingston, Canada.

Taylor, S. E., Rankin, G. I. B., and Cleland, D. J. (2002), “Guide to Compressive Membrane Action in Bridge Deck Slabs,” Technical Paper 3, UK Concrete Bridge Development Group/British Cement Association, pp. 18-21.

Transit New Zealand Ararau Aotearoa, New Zealand Bridge Manual, 2nd edition, (2003). UK Highway Agency (2002), “BD 81/02: Use of Compressive Membrane Action in bridge

decks,” Design Manual for Roads and Bridges, V. 3, Section 4, part 20. Weishe, He. (1992), “Punching Behaviour of Composite Bridge Decks with Transverse

Prestressing,” Ph.D. Thesis, Queen’s University, Kingston, Canada. Wood, R. H. (1961), ‘Plastic and Elastic Design of Slabs and Plates”, Ronald, New York.

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Thank you