Stress-strain relation of FRP-confined concrete

An analytical model is introduced in this paper to predict the behavior of axially loaded circular concrete columns confined by fiber reinforced polymer (FRP) composites. This model is based on the confinement model introduced by Attard and Setunge (1996) for actively confined concrete, and a modified model developed for predicting the dilation behavior of concrete. The analytical model, which can predict stress-strain curves of both the increasing type and the decreasing type, is verified by experimental results reported by the authors and other researchers. A parametric study is presented to examine the effects of stiffness of FRP and the strength of concrete on stress-strain relations.