Title: Effect of Flexural Reinforcement on Punching Shear Resistance

Author(s): W. Dilger, G. Birkle, and D. Mitchell

Publication: Symposium Paper

Volume: 232

Issue:

Appears on pages(s): 57-74

Keywords: concrete cover; concrete design codes; punching shear;reinforcement ratio

DOI: 10.14359/14936

Date: 10/1/2005

Abstract:
This paper starts with a review of the major international codes with regardto the effect of the flexural reinforcement on the design equations for punching shearof two-way slabs. A review of experimental programs in which the main parameter isthe flexural reinforcement ratio follows. In addition to the flexural reinforcement ratio,the type and grade of reinforcement, the arrangement of the reinforcement and theconcrete cover are also investigated.Evaluation of the parameters investigated shows a distinct decrease of the punchingshear resistance with decreasing reinforcement ratio. If shear failure occurs beforeflexural yielding has developed, the value of the yield strength does not affect theshear resistance of slabs. A concentration of the flexural reinforcement in the vicinity ofthe column resulted in a strength increase only if the reinforcement was well anchored,otherwise the reduced bond of closely spaced reinforcing bars will not lead to anincrease in the punching shear strength. The test results on concrete cover are not fullyconclusive, but it is argued that it is the effective depth rather than the slab thicknessthat governs the shear and flexural behavior of a slab.