Nonlinear Finite Element Modelling for Reinforced Concrete Beams Retrofitted with FRP in Bending

For the purpose of simulating the behaviour of reinforced concrete (R.C)[1] beams retrofitted with fibre-reinforced polymers/plastics (FRP)[2] in bending, a finite element (FE)[3] modelling procedure has been developed throughout this paper. The FE software package ABAQUS CAE 6.11-3 was used. The data required for such modelling process are boundary conditions, geometric and material properties. Non-available material properties are obtained through experimentally verified numerical material models. FRP isotropic and orthotropic material models are compared; both models nearly yielded similar results. Also, perfect bond model and cohesive zone model for the interface between concrete and FRP have been compared. Unlike the perfect bond model, the cohesive zone model captured the debonding. The modelling procedure was validated through its application to R.C beams retrofitted with FRP in bending. The FE model results were compared to experimental results where both results were highly correlated. Such results include load-deflection curves and cracking pattern. The effect of sheet width and number of FRP layers is emphasized through performing a parametric study. Increasing sheet width is only effective at longer sheet lengths regarding increasing both; stiffness and load carrying capacity. Upon increasing the number of FRP layers, only shifting of the yielding point of reinforcement was noticed.