Experimental investigation on shear behavior of FRP post-tensioned concrete beams without stirrups

Abstract

To investigate the shear behavior of post-tensioned concrete beams with longitudinal fiber-reinforced polymer (FRP) reinforcements and without stirrups, seven large-scale beams, with a shear span-to-effective depth ratio of approximately 3.0, were tested. The test variables included the prestressing level, type of flexural reinforcement, and tendon profile. The shear crack width and slip were tracked using digital image correlation technique. It was found that the post-tensioned concrete beams failed in shear-compression or shear-tension, while the nonprestressed concrete beam failed in diagonal tension. The post-tensioned beams designed to have approximately the same longitudinal reinforcement stiffness, exhibited similar shear strength. Draping FRP tendons resulted in an increase of 8.8% in shear cracking strength, while it had slight effect on the maximum shear strength. In this study, it was demonstrated that arching action played a major role in the shear resistance of FRP post-tensioned beams, while the contribution of aggregate interlock was negligible.