Shear resistance of concrete contribution in RC beams under flexure and shear

A Reinforced Concrete (RC) beam subject to flexure and shear is designed to resist both the forces, flexure and shear. Bending resistance is developed under the action of concrete and flexural reinforcement. Shear resistance of the beam originates from two sources, concrete and shear reinforcement. All the national codes developed tables showing the shear resistance contributed by concrete for the grade of concrete and percentage of flexural reinforcement contained by the RC beam. Of the total shear on the beam, while part of it borne by concrete and the balance is taken care of by shear reinforcement; this is the shear design principle of RC beams. It has been noted for several years that the shear design procedure suffers from the inaccurate computation of shear resistance of concrete in RC beams; what is taken in design is lower than the actual shear resistance of concrete in a beam. ACI 318: 2014 brought the shear contribution of concrete closer to the test results. Such correction has to be made in IS 456: 2000. The six RC beams tests reported, contributed test results in this direction. © 2020, Springer Nature Switzerland AG.