Analytical model for predicting the shear strength of FRP-retro tted exterior reinforced concrete beam-column joints

In this study, a nonlinear procedure for analysis of a membrane element of a FRP strengthened concrete beam-column joint is proposed, based on a softened truss model. The procedure employs three equations for equilibrium, three for compatibility, and six for the constitutive laws of materials. The model is capable of analysing the nonlinear behaviour of RC beam-column joints under cyclic loading, and has three major attributes: nonlinear association of stress and strain in the presence of FRP, contribution of concrete damage by means of a softening coecient, and consideration of the bond eect between steel, FRP and concrete. The proposed model is applied to some previously tested and strengthened beam-column joints, and shows good predictions of their shear strength. The eect of various parameters on the response of a reinforced concrete beam-column joint, such as a column axial load, amount of FRP reinforcement, and FRP properties, has been studied in a parametric manner. It is observed that even a low quantity of FRP can enhance the shear capacity of the joint signicantly. Also, it is observed that the axial load increases the connement of the joint care, which, in turn, increases the shear capacity of the joint.