Finite element model for predicting the shear behavior of FRP-strengthened RC members

The shear behavior of FRP strengthened reinforced concrete (FRP strengthened RC) membrane elements can be predicted by developing logical models that satisfy the principles of mechanics of materials namely stress equilibrium, strain compatibility, and constitutive relationships of concrete, steel and, FRP reinforcements. The Softened Membrane Model (SMM), which was developed for predicting the shear behavior of reinforced concrete (RC) membrane elements, is extended to FRP strengthened RC members subjected to shear. This new analytical model, referred to as the Softened Membrane Model for FRP strengthened RC members (SMM-FRP), considers new constitutive laws for each material component of the member. Similar to the case of the SMM model for RC, this new SMM-FRP model can predict the entire stress-strain curve, including pre- and post-cracking, and the ascending and descending branches. The SMM-FRP is implemented into an OpenSees-based finite element program for a membrane 2-D element that will allow structural engineers to predict the monotonic responses of FRP strengthened RC members subjected to shear. The developed program is validated in this paper by the prediction of the monotonic responses of 10 FRP strengthened RC panels subjected to pure shear stresses. The good agreement between the experimental and analytical results confirms the validity of the analytical model in predicting the shear behavior of RC members strengthened with FRP sheets.