Shear resistance and calculation method of GFRP-reinforced concrete beams with CFRP mesh fabric as shear reinforcement

Abstract

This paper presents the experimental data and model’s predictions on the shear performance of fiber reinforced polymer (FRP)-reinforced concrete (FC) beams with E-glass FRP (GFRP) longitudinal bars and carbon FRP mesh fabric (CFRP-MF) transverse stirrups. One reinforced concrete (RC) beam and six FC beams with various CFRP stirrup arrangements were designed and loaded to shear failure in a four-point loading mode with two shear-span to depth ratios (λ = 1.5 and 2.5). The shear bearing capacity of CFRP-MF stirrups in the beam was comparatively analyzed and predicted with some existing specification formulas. The results show that the FC beams have equivalent shear resistance to the RC beam with equal strength stirrups, and that the shear contribution of CFRP-MF stirrups to FC beam’s shear capacity is 37.8 % higher than that of steel stirrups in RC beam under λ = 1.5. Comparing with the FC beam with CFRP strip fabric (CFRP-SF) stirrups, the FC beams with CFRP-MF stirrups have better abilities to suppress the development of diagonal cracks and the joint reinforcement in CFRP-MF can further increase the beam’s shear capacity. The shear strengths provided by CFRP-MF stirrups in FC beams were derived from experimental data and compared with the predictions calculated by code formulas. Finally, considering the differences between the experimental and calculated results, a modified shear capacity model based on the formula in GB 50608–2020 was constructed by taking the influences of crack inclination angle and longitudinal connection CFRP strips into account. The effectiveness of the proposed new model in predicting the shear capacity of GFRP-reinforced concrete beams with CFRP-MF stirrups is verified using the test data from this paper and some existing studies.