BENT EFFECT ON STRENGTH OF CFRP STIRRUPS

This paper summarizes an experimental program undertaken at the University of Manitoba to examine the performance of CFRP stirrups for concrete structures. A total of 16 specimens with different types of CFRP stirrups, along with four control specimens using steel stirrups, were tested to study the behavior and the mode of failure. Both ends of the stirrup were cast into concrete blocks that were subsequently jacked apart to simulate the loading conditions of concrete beams. A total of three medium scale beams reinforced for shear by CFRP stirrups, along with two control beams, were also tested. The variables considered were the type of material, bar diameter, stirrup anchorage and embedment length of the stirrup into the concrete. Test results of the blocks indicated that the strength capacity of the stirrups could be as low as 40 percent of the ultimate tensile strength of the material parallel to the fibres. Based on the beam tests, it is recommended to limit the strength of CFRP stirrups to 50 percent of the strength parallel to the fibres.