Punching Shear Behavior of Two-Way Slabs Reinforced with FRP Shear Reinforcement

This study investigated the punching shear behavior of two-way concrete slabs with glass-fiber-reinforced polymer (GFRP) bars as flexural reinforcement and FRP stirrups (glass or carbon) as shear reinforcement. A total of 10 full-scale interior slab-column specimens measuring 2,500×2,500 mm, with thicknesses of either 200 or 350 mm, and 300×300-mm square column stubs were fabricated and tested under monotonic concentric loading until failure. These tests aimed at investigating the behavior of GFRP-reinforced two-way concrete slabs reinforced with FRP stirrups as shear reinforcement and evaluating their contribution to the punching shear capacity. The investigated parameters were the flexural reinforcement ratio and the shear reinforcement type (glass FRP and carbon FRP stirrups) and ratio. The test results revealed that using FRP stirrups as shear reinforcement increased the punching shear strength and deformation capacity of the test slabs. The increased punching shear strength and deformation capacity were proportional to the flexural- and shear-reinforcement ratios. In addition, the performance was enhanced by reducing the brittleness of the specimens when FRP stirrups were used as shear reinforcement.