Effect of web bonded CFRP shear reinforcement on internal steel stress

ABSTRACT

A four-point iosipescu shear test is used to evaluate the effects of FRP reinforce-ment on crack width development and the combined effects of FRP and steel reinforcement. The test program indicates that the steel reinforcement yields following cracking in a concrete test specimen containing a single No. 13 - 400 MPa yield strength reinforcing bar. FRP bonded to the face of both precracked and uncracked test specimens resulted in the steel strain reaching and average of approximately 45 percent of the yield strain prior to failure of the FRP/concrete interface. This research concludes that it is not prudent to assume that the steel yields when bonded FRP is present. The recommended stress in internal steel reinforcement used in combi-nation with externally bonded CFRP is limited to 200 MPa for shear applications.