Effect of web reinforcement, size effects and high strength concrete on the shear strength of RC short beams

This study aims at investigating influence of the vertical and horizontal shear reinforcement, size effects as well as high strength concrete on the shear strength of short beams. A new design equation is proposed for predicting the shear strength of short beams. The proposed equation has three differences from the previously suggested design equations. First, existing empirical equations are all based on the short beam tests with normal strength concrete. However, the use of high strength concrete is gaining rapid popularity, in especially, tall building constructions. The experimental database used in this study comprises of tests which have concrete cylinder strengths up to 90 MPa. Second, the proposed equation takes the influence of size effects into account, as it is based on an experimental database comprising of tests of up to 1600 mm depth. Third, the influence of the vertical and horizontal shear reinforcement are taken into account differently from the previously suggested design equations. It is apparent that the horizontal shear reinforcement is not as influential on the shear strength as the vertical shear reinforcement in short beams that have a/ d ratios less than 2.5 and higher than 1. The proposed equation is compared with the existing design equations. It is apparent that the equation of authors is an improvement on the existing design equations as it has the least standard deviation and the least coefficient of variation among the previously suggested design equations.