FRP-confined high-strength concrete under axial cyclic compression

It is well established that the confinement of concrete with fiber reinforced polymer (FRP) composites can lead to a significant increase in both the compressive strength and ultimate strain of concrete. In recent years, a large number of models have been developed to model the stress-strain behavior of FRP-confined concrete under monotonic loading. However, the studies on the axial cyclic response of FRP-confined concrete have been much more limited. Furthermore, most of the studies focused on normal-strength concretes (NSC) with strengths lower than 60 MPa, and research on FRP-confined high-strength concrete (HSC) has been very limited. This paper presents the results of an experimental study on the cyclic compressive behavior of FRP-confined HSC with unconfined concrete strengths up to 110 MPa. A total of 18 FRP-confined concrete cylinders were prepared using two different concrete mixes and two different types of fiber confinement (i.e., carbon and aramid) in order to investigate the effects of cyclic loading on the behavior of FRP-confined concrete. Results obtained from the monotonic and cyclic axial compression tests are presented in the form of axial stress-strain relationships and the effect of the load cycles on the compressive behavior of FRP-confined concrete with various confinement parameters are examined. Test results indicate that envelope stress-strain curves of cyclically loaded FRP-confined concrete closely follow the stress-strain curves of the same concrete under monotonic loading. The results also indicate that load cycles may lead to an increase in the compressive strength and ultimate axial strain of FRP-confined concrete.http://www.cice2008.org