Torsion Tests of R/C Beams With Large Openings

Abstract

An experimental investigation to study reinforced concrete beams with large rectangular openings under pure torsion is reported. The beams were rectangular in cross section. Beam dimensions, and the amount and arrangement of reinforcement were held constant, but opening sizes and their locations were varied. Test results of ten beams are presented and discussed. Torsional strength and stiffness of a beam decrease with increasing opening length or depth, but appear to be marginally influenced by its eccentricity. The beams fail by the formation of a mechanism with four hinges, one at each corner of the opening. Good predictions of the ultimate torque can be obtained by using the theoretical model proposed by the writers in a companion paper.