Study on reinforced concrete beams strengthened using shape memory alloy wires in combination with carbon-fiber-reinforced polymer plates

It has been proven that carbon-fiber-reinforced polymer (CFRP) sheets or plates are capable of improving the strength of reinforced concrete (RC) structures. However, residual deformation of RC structures in service reduces the effect of CFRP strengthening. SMA can be applied to potentially decrease residual deformation and even close concrete cracks because of its recovery forces imposed on the concrete when heated. Therefore, a method of a RC structure strengthened by CFRP plates in combination with SMA wires is proposed in this paper. The strengthening effect of this method is investigated through experiments and numerical study based on the nonlinear finite element software ABAQUS in simple RC beams. Parametric analysis and assessment of damage by defining a damage index are carried out. The results indicate that recovery forces of SMA wires can decrease deflections and even close cracks in the concrete. The recovery rate of deflection of the beam increases with increasing the ratio of SMA wires. The specimen strengthened with CFRP plates has a relatively large stiffness and smaller damage index value when the residual deformation of the beam is first reduced by activation of the SMA wires. The effectiveness of this strengthening method for RC beams is verified by experimental and numerical results.