Punching Shear Resistance of Interior GFRP Reinforced Slab-Column Connections

Abstract

This paper deals with the punching shear resistance of flat slabs reinforced with glass fiber-reinforced polymer (GFRP) reinforcing bars. A total of six large-scale interior GFRP and steel reinforced slab-column connections with the varying longitudinal tensile reinforcement ratio were tested. A new fracture-mechanics-based empirical formula for estimation of the punching shear resistance of interior GFRP reinforced slab-column connections is also presented in the paper. The formula takes into account effects, span to the effective slab-depth ratio, depth of the compression zone, dowel action, and the size effect on the punching shear resistance of flat slabs reinforced with GFRP bars. The accuracy of the proposed formula was verified against test results obtained by the authors and also by other researchers. In comparison with already known formulas, the proposed formula is in good agreement with the test results and provides predictions of the punching shear resistance with the smallest scatter. A physically reasonable relation between experimental punching resistances and reinforcement ratios of both the GFRP slabs and the steel reinforced concrete (SRC) slabs was obtained when equivalent GFRP reinforcement areas were used for SRC slabs. Predicted punching resistances of SRC slabs, calculated based on the equivalent GFRP reinforcement area, were found to be approximately equal to the resistances of GFRP slabs when the behavior (load-displacement diagram) of SRC slabs resembled the one of GFRP reinforced slabs.