Compressive behavior and modeling of concrete wrapped by hybrid low-high elongation capacities FRP

This paper experimentally investigated the monotonic and cyclic compressive behavior of concrete confined with hybrid carbon fiber-reinforced polymer (CFRP) and large rupture strain (LRS) FRP. A total of 34 concrete cylinders wrapped by FRP were prepared and tested under monotonic/cyclic axial compression. The effects of FRP types and thickness on the failure mode, efficiency factor, hybrid effect, stress-strain response, and energy dissipation were carefully investigated. Test results verified that the hybrid confinement mechanism can fully utilize the advantages of both types of FRP and avoid their essential shortcomings. LRS FRP effectively improved the utilization of CFRP and increased the deformation and energy dissipation capacity of concrete. Hybrid inner CFRP and outer LRS FRP serve as a confinement device that can achieve a progressive failure mechanism for concrete. In addition, an analysis-oriented model was developed and constructed to simulate the monotonic stress-strain behavior of hybrid-wrapped concrete. This analysis-oriented model focuses on the lateral stressstrain relationship and the localized CFRP fracture effect. Finally, a cyclic stress-strain model of hybridwrapped concrete was developed using the analysis-oriented model as an envelope model. The proposed model can accurately capture monotonic/cyclic stress-strain behaviors.