Punching Shear Behavior of GFRP-RC Slab-Column Edge Connections

摘要

Flat plate systems are susceptible to punching shear failure, which occurs due to the high shear stresses transferred between the slab and the column at a slab-column connection. On the other hand, the use of fiber reinforced polymer (FRP) bars as reinforcement for reinforced concrete (RC) structures has proved to be an effective solution to the steel corrosion problem. Nevertheless, FRP bars have a relatively low axial and transverse stiffness compared to steel bars, which results in a lower punching capacity of the slab-column connection. This paper presents test results of five full-scale slab-column edge connections; one connection was reinforced with steel bars, one with glass (G) FRP ribbed-deformed bars, and three with GFRP sand-coated bars with different reinforcement ratios. The tests were designed to study the effect of flexural reinforcement type and ratio on the punching behavior of slab-column edge connections. All connections failed in a brittle punching shear mode; however, the GFRP-RC connections exhibited significant deformations leading to ample warning before failure. In addition, increasing the GFRP reinforcement ratio increased the punching capacity and the post-cracking stiffness of the connections. Moreover, CSA/S806-12 and JSCE 1997 provided reasonable, but slightly conservative, predictions; however, ACI 440.1R-15 highly underestimated the capacities.