Shear behavior of concrete panels reinforced with GFRP bars under cyclic diagonal tension tests

Abstract

Glass Fiber Reinforced Polymer (GFRP) bars aims to improve the properties of concrete conventional reinforcement and to reduce the weaknesses of steel rebars in terms of corrosion and temperature changes. In this study, GFRP bars were evaluated as a replacement of steel bars in shear walls. Diagonal tension test under unreversed cyclic quasi-static load on Reinforced Concrete (RC) panels was used. Twenty-one concrete panels with a square section, 600 mm on each side and 100 mm thick, reinforced with distinct types and reinforcement ratios were evaluated. Two types of GFRP bars with different surface coating were used: epoxy Helical wrap (GFH), and Sand coated (GFS). For comparison purposes, RC panels with steel Welded Wire Mesh (WWM) were also assessed. The minimum vertical and horizontal reinforcement required by ACI 318 (0.25%) and half of it (0.125%) were considered. The research analyzed the hysteresis curves in terms of shear stress-strain (τ-γ) and the parameters associated with shear strength, shear strain, crack width, stiffness, and toughness. Results showed that the stiffness and toughness of panels reinforced with GFH bars is similar to that of RC panels with WWM, and the toughness of panels reinforced with GFS bars is between 25% and 38% higher than those with WWM. Different models are proposed to estimate the stiffness, toughness, and crack width of the tested panels.