Cyclic stress–strain model of fiber-reinforced polymer-confined square rubber concrete columns

Extensive research has been conducted on the mechanical behaviors of fiber-reinforced polymer (FRP)-confined circular rubber concrete columns. However, there are very few studies on the axial stress–strain behavior of FRP-confined square rubber concrete columns, and no cyclic stress–strain model has been proposed. To fill this gap, an experimental study on the axial monotonic and cyclic compression of 72 FRP-confined square rubber concrete columns was conducted in this paper. During the test preparation, three parameters (i.e., rubber volume replacement ratio [0%, 40%, and 60%] of fine aggregates, cross-sectional corner radius [15, 45, and 60 mm], and FRP layers [one layer and two layers]) were considered. Experimental results show that all of these parameters significantly affect the monotonic and cyclic stress–strain curves. Based on the experimental findings, a new cyclic stress–strain model of FRP-confined square rubber concrete columns was developed, having good agreement with test results.