Flexural performance of U-shape fiber-reinforced polymers profile-concrete composite beams under static and cyclic loads

Abstract

This paper mainly focuses on flexural behavior of U-shape HFRP profile-concrete composite beams under static and cyclic loading. Four-point-bending experiments of eight pieces of HFRP-RC composite T-shaped beams with shear keys combined with wet-bond interface under both static and cyclic loads were conducted. The fiber-reinforced polymers profiles were produced by using vacuum infusion molding process. Experiment phenomena were detailed, and flexural performance such as failure mode, capacity, stiffness and load–displacement curves was also analyzed. Result shows that the shear keys combined with wet-bond interface is effective. Meanwhile, the flexural performance of the fiber-reinforced polymers-reinforced concrete beams under cyclic load was simulated based on the OpenSees software, in which special constitutive models of different materials were chosen to consider the cyclic loading. The simulation results and the experimental results such as the load–displacement curves, unloading stiffness, residual displacements, etc. were compared. The results show that OpenSees system can simulate the flexural performance of the fiber-reinforced polymers-reinforced concrete beams under both monotonic loads and cyclic loads very well. And then parameters study was conducted by using simulation method, and the influence factors such as concrete strength, steel bar ratio, fiber-reinforced polymers types, tensile stiffness of the longitudinal fiber-reinforced polymers, etc. were analyzed. Meanwhile, the recoverability of the fiber-reinforced polymers-reinforced concrete composite beams was evaluated, and a modified formula for the residual deformation was put forward. Finally, an idealized type of fiber-reinforced polymers-reinforced concrete beams with a medium reinforcement ratio and high post-yield stiffness was proposed, and reasonable values of the secondary stiffness ratio (defined as post-yield tangent stiffness divided by post-crack tangent stiffness) are recommended.