Analytical approach for predicting full torsional behavior of reinforced concrete beams strengthened with FRP materials

A new computational procedure is developed to predict the full torsional response of reinforced concrete beams strengthened with Fiber Reinforced Plastics (FRPs), based on the Softened Membrane Model for Torsion (SMMT). For validating the proposed analytical model, torque-twist curves obtained from current theoretical approaches are compared with experimental ones for both solid and hollow rectangular sections. The good agreement results of this comparison show that the proposed analytical model is reliable for predicting the torsional behavior of FRP-strengthened reinforced concrete beams before and after cracking. By means of the developed approach, the power of the SMMT method, in extending to FRP-strengthened reinforced concrete beams, is demonstrated in this paper. Moreover, the contribution of FRP fabrics to the torsional response, as an external bonded reinforcement, is studied in various practical strengthening configurations. Therefore, the efficiency of each configuration is illustrated as well.