Fiber-reinforced polymer shear strengthening of reinforced concrete beams: Experimental study and analytical modeling

In this paper, the results of an experimental investigation on reinforced concrete (RC) rectangular beams strengthened in shear with externally bonded U-wrapped carbon fiber-reinforced polymer (CFRP) are presented and discussed. The results provide some new insights into the complex failure mechanisms that characterize the ultimate shear capacity of RC members with transverse steel reinforcement and FRP sheets and show some mechanisms of interaction between the externally applied FRP sheets and the internal shear steel reinforcement with different static schemes. This interaction is not considered in the actual code provisions but strongly influences the efficiency of the shear strengthening rehabilitation technique and, consequently, the calculation of the interacting contributions to the nominal shear strength of the structural member. On the basis of the observation of the experimental shear behavior, an analytical model, which allows the estimation of the interacting contributions to the shear capacity of the strengthened beams, is proposed.