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Punching Shear Strength of Transversely Prestressed Concrete Decks

  1. Punching Shear Strength of Transversely Prestressed Concrete Decks Sana Amir 04-07-2012 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: Past Research: Existing methods 3: Punching Shear in Transversely Prestressed Concrete Decks: Analysis methods 4. Future experiments 5. Conclusions Titel van de presentatie 2
  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). Titel van de presentatie 3
  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. ? • Prestressing provides additional in-plane forces. Therefore, there is a need to investigate the use of transverse prestressing in bridge decks considering CMA. Titel van de presentatie 4
  5. Past Research / Hewitt & Batchelor Model Pp = 1.52(φ + d )d f c (100Qe )0.25 Kirkpatrick, Rankin, Long, Taylor Provided the limitations are satisfied, charts from UK HIGHWAY AGENCY STANDARD BD 81/02 OHBDC (1979), NZ Code can be used for strength assessment. Titel van de presentatie 5
  6. Mikael Hallgren Model • 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. Limitation: Analysis of symmetric punching of reinforced slabs without shear reinforcement – Open to further development. Titel van de presentatie 6
  7. Punching Shear Failure Transversely Prestressed Concrete Decks • Provisional of additional in-plane forces due to prestressing • Improved punching shear capacity • Improved serviceability Titel van de presentatie 7
  8. Analysis Methods Engineering Method Modified Hallgren Model ρps f pe ρe = ρs + 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) Titel van de presentatie 8
  9. Tests by Kirkpatrick et al (1984) Capacity predictions for reinforced concrete decks by UK Highway BD81/02 and modified Hallgren model. Titel van de presentatie 9
  10. Application to Experimental Data TPL ~ Punching Load 100 Pt 90 η - TPL relationship Pmh 80 0.8 Ph&b 70 0.7 PNZ 0.6 60 R² = 0.8233 0.5 50 0.4 η N L P k d h n u a o g c ) ( i 0.3 40 0 1 2 3 4 5 0.2 TPL (MPa) 0.1 0 Method of superposition 0 1 2 3 4 5 6 TPL (MPa) Variable Restraint Factor Savides (1989), He (1992) Tests in Queen’s University, Kingston, Canada Titel van de presentatie 10
  11. FUTURE TESTS Transverse Prestress Level 1.25 MPa 2.5 MPa 6400 Titel van de presentatie 11
  12. Main Parameters: Transverse Prestress Level Skewness of the joints Loading position CMA Titel van de presentatie 12
  13. Conclusions • 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. Titel van de presentatie 13
  14. 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. Titel van de presentatie 14
  15. Thank you Titel van de presentatie 15