Cyclic compressive behavior of concrete confined with large rupture strain FRP composites

Fiber-reinforced polymer (FRP) composites with a large rupture strain (LRS) (i.e., having an ultimate tensile strain larger than 5%) are promising jacketing materials for the seismic retrofit of reinforced concrete (RC) columns. These LRS FRPs are environmentally friendly as their reinforcing fibers can be made from recycled plastics [e.g., polyethylene terephthalate (PET) bottles]; as a result, they are also cheaper than conventional FRPs [i.e., carbon FRP (CFRP), glass GFRP (GFRP), and aramid FRP (AFRP)]. This paper presents the first-ever study on the behavior and modeling of LRS FRP-confined concrete under cyclic axial compression. Experimental results are first presented to examine both the envelope compressive stress-strain curve and the cumulative effect of loading cycles. A cyclic stress-strain model is then proposed and shown to provide close predictions of the test results. The proposed cyclic stress-strain model is formed by combining an existing monotonic stress-strain model for predicting the envelope curve with an existing cyclic stress-strain model for predicting the unloading and reloading paths. This cyclic stress-strain model can be employed in modeling the behavior of LRS FRP-jacketed RC columns subjected to seismic loading.