Punching Shear Strength Model for Reinforced Concrete Flat Slabs with Openings

Abstract

A theoretical model is proposed to analyze the punching shear resistance in flat slabs of reinforced concrete in the presence of openings and stud-type shear reinforcement. Openings in flat slabs reduce resistance to punching. The magnitude of the loss of strength is influenced by the quantity, size, and position of the opening in the slab. The theoretical method presented in this work describes that once a load is applied onto the slab, a rotation occurs, giving rise to seven forces. These forces are related to the concrete and the flexural and shear reinforcement. The failure load is calculated by finding the solution of nonlinear equations developed from horizontal, vertical, and rotational balance of these forces. The failure criterion of these slabs with shear reinforcement was classified as internal or external to the shear reinforcement. The results showed theoretical breaking loads similar to those obtained experimentally, with a maximum variation of 7%.