ULTIMATE TORQUE OF REINFORCED RECTANGULAR BEAMS

Abstract

The ultimate resisting torque of a reinforced concrete member can be considered as the sum of the contributions of concrete and steel. In a reinforced member there is a necessity for minimum percentage of longitudinal and stirrup steel to avoid brittle failure at initial cracking. The overbalanced part of the reinforcement in a partially overreinforced section does not appear to contribute to the ultimate torque significantly. The overbalanced parts of the longitudinal and stirrup steel in a completely overreinforced section do contribute to the ultimate resisting torque; but the efficiency of the total steel against torsional resistance reduces considerably with increased overreinforcement. An average of test to calculated ultimate torque ratios given by the present expression for 85 specimens has been found to be 1. 00 with a standard deviation of 0. 07.