Punching shear strength of interior concrete slab-column connections reinforced with FRP flexural and shear reinforcement

To predict the punching shear strength of interior reinforced concrete (RC) slab-column connections using fiber reinforced polymer (FRP) bars as flexural and shear reinforcement, an analytical study was performed. Based on the punching shear failure mechanism of FRP-RC slab-column connections, a design method was proposed addressing the features of FRP reinforcement. For an accurate strength prediction, the depth of compression zone was evaluated by a modified approach, formulas for the effective strain and strength contribution of FRP shear reinforcement were proposed, and the effects of the size, aspect ratio, and load eccentricity were included. For verification, predictions by the proposed method were compared with existing test results for FRP-RC slab-column connection specimens with or without FRP shear reinforcement and subjected to concentric or eccentric load, and the accuracy and reliability of the proposed method were thoroughly examined by comparing with the current design codes and existing models. The comparisons showed that the proposed method best matched with the various test results consistently for all design parameters. To give an insight into the design of FRP-RC slab-column connections, the effects of various design parameters on the punching shear strength were also analyzed in detail.