Punching shear behavior of normal and high-strength concrete flat-plates

Abstract

The use of flat-plate is becoming popular for medium rise residential and office buildings. The connection between the slab and the column in flat-plate structures is generally the most critical part. The failure of the connection, called punching shear failure, takes place when a plug of concrete is pushed out of the slab immediately under the loaded area. In the last decades, there occurred many developments in the concrete technology. Among these developments, the production of high strength concrete (HSC) and the use of steel fibers (SFR) have made major impacts on the structural systems. The rapid growth of interest in these developments made the design equations and national building codes, in some areas, to fall behind the prevailing concrete technology. An experimental and analytical investigation on the punching shear strength and behavior of flat-plates is performed. The effect of use of HSC compared to normal strength concrete (NSC), different load eccentricities and slab reinforcement ratios, and the addition of SFR to NSC and HSC is investigated experimentally. Using the available test results in the literature and the results of the author, a data base is formed and through an iterative error minimization approach a design equation is proposed for the case of concentric punching. The post-failure behavior of the specimens are also investigated and a residual strength equation for the failed connections is proposed.