Bending and Shear Behavior of Plain and PVA-Fiber Reinforced Concrete Beams with GFRP Reinforcing Bars

Glass fiber-reinforced polymer (GFRP) bars represent an effective alternative to traditional steel internal reinforcement of concrete members when durability is a concern. However, GFRP bars have elastic moduli smaller than that of steel and a different bar-concrete bond behavior, which entail large deflections and openings of concrete cracks at both serviceability and ultimate limit states. Due to their crack bridging effect, the addition of dispersed polyvinyl alcohol (PVA) fibers to the concrete mix allows reducing the tensile forces carried by the bars and consequently reduce crack opening and beam deflection. The PVA fiber-reinforced concrete (PVA-FRC) element with FRP bars becomes a corrosion resistant system with a structural behavior that can reach a load-carrying capacity comparable to that of traditional steel RC structures with equivalent amount of reinforcement. This paper investigates the shear behavior of plain concrete (PC) and PVA-FRC beams with GFRP bars as internal longitudinal and transverse (stirrups) reinforcement. Four-point bending tests are performed on PC and PVA- FRC GFRP-reinforced beams. The experimental campaign on full-scale concrete structural elements provides fundamental information on the synergy between PVA-FRC and internal GFRP bar reinforcement. The addition of short PVA fibers significantly increases the beam shear strength, and the results obtained provide an insight into the role of GFRP stirrups and PVA FRC in the shear crack propagation.