Composite materials have attracted wide attention in structural engineering research as they present exceptional advantages when used to strengthen structural members. In this study, the behavior of rectangular reinforced concrete (RC) strengthened with fiber reinforced polymer (FRP) laminates under pure torsion was analyzed by ABAQUS Software program. The experimental data was obtained from existing literature on the subject. The contribution of FRP, as an external bonded reinforcement, to torsional response is studied in various practical strengthening configurations and the efficiency of each configuration was illustrated. The paper presents the method and requirements of material parameters identification for a concrete damage plasticity constitutive model. Good agreement in terms of torque–twist behaviors of concrete beams reinforced with FRP laminates before and after cracking was found. Steel and FRP reinforcement responses as well as crack patterns were achieved. The unique failure modes of all the specimens were modeled correctly as well. A parametric study was carried out after model validation by varying the number of FRP plies, concrete compressive strength, and FRP strip orientations. The results showed that the torsional capacity of strengthened RC beams improves by increasing the number of FRP plies and concrete compressive strength as expected. The parametric study showed no significant change in the torsional capacity of RC beams when it was strengthened with a 45-degree or with a 90-degree FRP laminate.

Keywords