Non-linear finite-element investigation of the parameters affecting externally-bonded FRP flexural-strengthened RC beams

This paper presents a three-dimensional non-linear finite-element model developed to simulate the behaviour of reinforced-concrete (RC) beams strengthened in flexure with carbon fibre-reinforced polymers (CFRP). The model is used to identify the parameters that have a significant influence on the behaviour of FRP flexural-strengthened beams. The parameters investigated are the width, length, thickness, and elastic modulus of the FRP laminate, as well as the number of FRP layers. The effect of two flexural-strengthening schemes is studied: a beam with two FRP plates at the soffit of the beam beneath the longitudinal steel, and a beam with a double layer of CFRP plates on the bottom face of the beam. The accuracy of the finite-element model is validated against published experimental data. Comparisons between numerical predictions and test results show very reasonable accuracy in terms of ultimate load-carrying capacities, load-deflection relationships, and failure modes. Results of the parametric study indicate that for some parameters, there is a threshold for the contribution of FRP laminates. The effect of the two flexural-strengthening schemes on the behaviour of FRP flexural-strengthened beams is also demonstrated.