Experimental investigation of stirrup confinement effects on bond-slip responses for corner and middle bars

Abstract Stirrup confinement on bond between concrete and reinforcement is vital for RC (reinforced concrete) structures as it strengthens the friction and mechanical interlock between the two kinds of materials. In this paper, an experimental study has been carried out to look into the stirrup effects on bond-slip responses of RC with corner embedded reinforcing bars and bars embedded in the middle area of cover (corner and middle bars). This aims to quantify the difference of the bond strength caused by the embedment position of reinforcement while confined with hooked and straight stirrups. Different material properties have also been considered in the experiment including concrete cover, bar diameter and stirrup diameter. The failure modes for different specimen groups are presented and discussed. Besides, the influence of stirrup confinement effects on global load-slip response is also investigated by conducting another experiment with long embedment length of reinforcing bars which also includes the corner bars and middle bars. Furthermore, the debonding resistance compared with yielding force of the reinforcing bars are compared and analyzed for the global load-slip responses with stirrup confinements.