Bond performance of FRP bar reinforced concrete under monotonic load and fatigue effect

In order to investigate the bonding properties of FRP-reinforced concrete under different loads, a series of FRP-reinforced concrete specimens were subjected to pull-out tests. Three types of reinforcement were used in the experiment: ordinary steel reinforcement, carbon fiber reinforcement (CFRP), and glass fiber reinforcement (GFRP). Pull-out tests were first conducted under monotonic load to determine the effect of concrete strength and reinforcement diameter on the bond performance of FRP bar-reinforced concrete and steel-reinforced concrete. The investigation of the variation of bond performance under different reinforcement materials was made. Second, a fatigue test was done, followed by further pull-out tests to get the bond stress-slip curve between concrete and reinforcement, and the influence of fatigue action on the bond stress-slip curve was further examined. The formulae to calculate the stress were developed, which can be applied to determine the bond failure pattern, bond strength, and bond-slip curve.