Optimum Configuration of CFRP Composites for Strengthening of Reinforced Concrete Beams Considering the Contact Constraint

In this paper, finite element analysis (FEA) was conducted using ABAQUS to simulate and evaluate the response of reinforced concrete beams strengthened with different configurations of CFRP composites. The investigated parameters include: the number of layers of CFRP sheets, compressive strength of concrete, and orientation of CFRP sheets. The beams were 1500 mm long with cross-section dimensions of 100 x 200 mm, loaded as simply supported beams under three-point loading configuration. Concrete damaged plasticity model was chosen and the models were calibrated and validated properly. The nature of the contact between the CFRP composites and concrete was carefully evaluated in order to arrive at the optimum contact definition. The results showed that the performance of the beam was noticeably improved using up to three CFRP layers; any number of CFRP layers above three were ineffective. This indicates that it is important to optimize the number of sheets in a CFRP composite based on the beam dimensions and reinforcement to minimize the cost and avoid adversely affecting the ductility of the strengthened beam. Regarding the influence of compressive strength, the enhancement in the performance of the CFRP strengthened beams was pronounced when increasing the strength, however it was not significant. The use of U-shaped layout of CFRP composites was the most effective configuration. Finally, the use of shell to solid coupling contact constraint shows the least error while allowing relative movement between beam surface and CFRP composites.