Investigations of HSC punching shear capacity in flat slabs

Abstract

Slabs punching shear capacity for normal strength concrete (NSC) and high strength concrete has been investigated in this paper. Due to the significance of concrete technology in the construction industry, more attention has been paid to high strength concrete in this paper. Then, detailed comparison is carried to evaluate the outcome by referring to several existing standards.

Slabs punching tests have been collected from the reported results in the literature.  Forty-seven tested slab specimens have been grouped from the available published information.  In this work, the collected specimens are studied thoroughly, and a conclusion has been drawn from the preliminary investigation that punching shear failure is a common feature in the forty-seven specimens. The collected concrete slab specimens have diversified cylinder compressive strength ( ) ranged from 14.4 MPa to 119 MPa. However, the application of ( ) in existing codes is restricted to a limit as mention hereafter. American Concrete Institute (ACI-14) limits the practical application of  to 69MPa, while The Australian Concrete Structures Standard (AS-94) limits  to 50 MPa. The recent evolvement in concrete technology has made the production of HSC with  much greater than the aforementioned values affordably reachable. Therefore, the present research attempts to bridge this gap and goes beyond the standards restrictions. This has been achieved by proposing a new design equation for punching shear through applying a regression analysis. The accuracy of the proposed equation and the existing equations have been examined by utilizing statistical analysis [Arithmetical mean ( ), Variation (VAR), Standard Deviation (SD) and Coefficient of Variation (COV)] to the punching shear failure strength values. The proposed method results for , VAR, SD and COV are 1.575, 0.364, 0.1299 and 23.128% respectively, and these are smaller when compared with the other 6 existing code methods.