Stress-strain behavior of polyethylene terephthalate fiber-reinforced polymer -confined normal-, high- and ultra high-strength concrete

Polyethylene terephthalate (PET) fiber-reinforced polymer (FRP) composites, which are made from recycled PET products and exhibit large rupture strain (LRS), have gained more and more attention in recent years on account of their environmentally friendly origin. One promising application of such fibers is in the confinement of concrete. Research is, however, limited and particularly for the stress-strain behavior of PET FRP-confined concrete. In light of such a knowledge gap, this paper presents an experimental investigation on the stress-strain behavior of PET FRP-confined normal-, high- and ultra high-strength concrete cylinders. It is found that the stress-strain behavior of the confined high-strength (as well as ultra high-strength) concrete specimens exhibits a strain hardening-softening-hardening behavior, while the confined normal-strength concrete specimens generally exhibit a monotonic ascending behavior. In addition, all concrete grades confined with the PET fibers exhibit a typical axial strain-hoop strain curve with an inflection point. A new design-oriented stress-strain model is then proposed based on a comprehensive review of experimental data for PET FRP-confined normal-, high- and ultra high-strength concrete. Comparisons between experimental results and predictions show that the proposed model provides satisfactory predictions for PET FRP-confined concrete.