Evaluation of minimum shear reinforcement in reinforced concrete beams

Abstract

Failures in reinforced concrete (RC) structures under shear loads are proved to be brittle with the presence of web reinforcement. The minimum web reinforcement specified by many codes of practice is intended to maintain adequate reserve strength and ductility after the diagonal cracking and to control widening of diagonal cracking. However, the expressions for estimating the minimum shear reinforcement in codes of practice are based on the experimental data base observed on small beam depth made of normal strength concrete (NSC). Hence, these provisions need to be reassessed and altered for large size members made of high strength concrete (HSC). Further, there has been no consensus on the amount of shear reinforcement to be provided by different codes of practice, as they differ significantly in respect of HSC members. In this paper, many factors influencing the minimum shear reinforcement in RC beams has been incorporated. An expression has been proposed incorporating a wide range of concrete strengths. A comparison of the minimum shear reinforcement predicted by the proposed expression has been made with the codes of practice.