Behavior of reinforced concrete beams with minimum torsional reinforcement

An experimental investigation was conducted on the behavior of thirteen high-(HSC) and normal-strength concrete (NSC) full-size beams with relatively low amounts of torsional reinforcement. The crack patterns, the maximum crack widths at service load level, torsional strength, torsional ductility, and post-cracking reserve strength results of the experiments are discussed. The main parameters include the volumetric ratio of torsional reinforcements, the compressive strength of the concrete, and the aspect ratio of the cross section. It was found that the adequacy of the post-cracking reserve strength for specimens with relatively low amounts of torsional reinforcement is primarily related to the ratio of the transverse to the longitudinal reinforcement factors in addition to the total amounts of torsional reinforcement. The minimum requirements of torsional reinforcement for NSC beams proposed by other researchers are also discussed on the basis of our test results of both HSC and NSC beams.