Punching shear behavior of GFRP-reinforced concrete flat slabs using finite element analysis

Glass fiber-reinforced polymer (GFRP) bars are an alternative to traditional steel reinforcement, which is increasingly used in flat slab applications. A better understanding of the punching shear response of such slabs is needed to promote further confidence in using GFRP bars as reinforcement for flat slabs. The current paper uses finite element analysis (FEA) software to develop a 3D model with the appropriate element type and mesh and constitutive modeling of concrete and reinforcement to investigate the punching shear behavior of interior GFRP-reinforced concrete flat slabs. The developed FEA model is calibrated and verified by ten slabs experimentally tested for punching shear, including two calibration samples tested by the authors and eight verification samples from the literature. The proposed FEA model accurately predicts the ultimate load, cracking patterns, reinforcement strains, load-deflection curves, and overall slab behavior consistent with the experimental results. The punching shear capacity predicted by the proposed FEA model is compared against three international design codes. The study found that the FEA model is a reliable tool for predicting the punching shear behavior of GFRP-reinforced flat slabs.