Experimental and Theoretical Investigation of the Punching Shear Strength of GFRP-Reinforced Two-Way Slabs

Abstract

This study aims at investigating the punching shear behavior of square RC interior slab–column connections reinforced with glass fiber reinforced polymer (GFRP) rebars. A total of eight specimens are tested under vertical shear until failure. Five of the specimens are reinforced with GFRP rebars and three specimens with conventional steel reinforcement for comparison. The investigated test parameters are flexural reinforcement type (GFRP or steel), column stub dimensions (100 mm × 100 mm or 150 mm × 150 mm), slab dimensions (900 mm × 900 mm or 1200 mm × 1200 mm), and slab thickness (100 mm or 120 mm). The slenderness effect is also taken into account by testing specimens with varying span lengths and thicknesses. The 3D nonlinear finite element method (FEM) is also implemented to validate the experimental findings. Additionally, the accuracy of existing design equations is assessed against the experimental results. The results reveal that GFRP-reinforced specimens yield higher deformation capacity, yet lower punching shear strength, as compared to steel-reinforced counterparts, owing to the lower elastic modulus of GFRP rebars. Although neglected in most studies, the net span-to-depth ratio (L net /d) is a substantial parameter and should be considered in design.