SHEAR., I 1 OF FOR D CONCRETE BEAMS

Abstract

The problem of determining the shearing strength of reinforced concrete beams has received a great deal of attention in the technical literature. A large number of laboratory investigations have been reported and empirical methods have been proposed for predicting the shearing strength of beams without and with web reinforcement. However, the complexity of the problem is so great that as yet no adequate analytical solution of the problem has been developed. Such concepts as shear capacity of critical sections, aggregate interlock, truss analogy, and others that form the basis of American Concrete Institute, British Standards Institution, Cement and Concrete Association code provisions for shear design, are in conflict with the observed structural behavior. In this experimental investigation an appraisal has been made of the concept of shear capacity of critical section which forms the basis for the shear design procedures in most of the current design codes. The detailing of the web reinforcement and the shear span-to-depth ratio, a„ /d, were taken as the main variables in the investigation so as to comparatively evaluate the performance of the simply supported singly-reinforced RC beams with. different configuration of web reinforcement. The results of this investigation confirm and reiterate the earlier observations in the literature that the concept of shear capacity of a critical section is insufficient to describe the underlying causes of the observed shear behavior of RC beams. This investigation demonstrates that although shear failure can be prevented by complying with current codal shear design provisions, a more significant contribution of shear reinforcement is to ductility of the RC beams. This investigation presents evidence that adequately designed shear reinforcement is an imperative to achieve potential ductile response in a typical under-reinforced RC beam.