BEHAVIOR OF RC HOLLOW BEAM UNDER PURE CYCLIC TORSION

Abstract

Twisting Moment in the member of the skeletal structure due to wind, seismic and other lateral loads are invariably repetitive and cyclic in nature. The reinforced concrete (RC) beam have been found deficient in torsional shear capacity and the behavior of RC beam under torsion is still a topic of research in structural engineering. This paper attempts to evaluate the effect of main reinforcement and shear reinforcement on the behavior of RC hollow beam under pure cyclic torsion and also studied the crack pattern. In present experimental study total 12 RC hollow beams were casted with different amount of longitudinal and shear reinforcement and tested under pure cyclic torsion. The parameters studied were cracking torque, angle of twist, energy dissipation, crack pattern and failure mode. It has been found that in pre cracking mode, reinforcement are ineffective for resisting the torsion moment but in post cracking mode all the torsional moment are resisted by the main rein-forcement. It was overserved that longitudinal reinforcement increase the torsional flexibility of beam, for the same amount of transverse reinforcement. It was also found from the experiment that optimum spacing of transverse reinforcement is equally important parameter while designing for the torsional reinforcement.