An investigation of stress-strain behavior of FRP-confined concrete under cyclic compressive loading

One important application of fiber reinforced polymer (FRP) is to confine concrete as FRP jackets in seismic retrofit process of reinforced concrete structures. Confinement can improve concrete properties such as compressive strength and ultimate axial strain. For the safe and economic design of FRP jackets, the stress-strain behavior of FRP-confined concrete under monotonic and cyclic compression needs to be properly understood and modeled. According to literature review, it has been realized that although there are many studies on the monotonic compressive loading of FRP-confined concrete, only a few studies have been conducted on the cyclic compressive loading. Therefore, this study is aimed at investigating the behavior of FRP-confined concrete under cyclic compressive loading. A total of 18 cylindrical specimens of FRP-confined concretewere tested in uniaxial compressive loading with different wrap thickness, and loading patterns. The results obtained from the tests are presented and examined; based on analysis of test results predictive equations for plastic strain and stress deterioration were derived. The results are also compared with those from two current models,comparison revealed the lack of sufficient accuracy of the current models to predict stress-strain behavior and accordingly some provisions should be incorporated.