Shear Behavior of RC Beams Strengthened Externally with Bonded CFRP–U Strips

Abstract

This paper aims to contribute to a better understanding and modeling of the shear behaviour of RC beams strengthened externally with carbon fiber reinforced polymer CFRP–U strips. Nine RC beams without internal shear reinforcement were tested; one beam was kept as a control beam; whereas other beams were strengthened externally with CFRP–U strips. Test variables were, effective height (depth) of CFRP–U strips, number and width of strips for the same shear reinforcement ratio, and spacing or amount of strips. Test results showed that, the ultimate shear capacity of RC beams can be increased significantly using this techniques, a maximum increase of 93% was obtained. For beams strengthened with the same amount of CFRP strips, increasing the number of fiber by decreasing the strip width has a slight effect on both carrying capacity and ductility of the beams. A simple improved model has been proposed to predict the contribution of CFRP–U strips to the shear capacity of the strengthened beams, which fail by CFRP debonding. Research recommendations have been given at the end.