Cyclic stress-strain model for FRP-confined concrete considering post-peak softening

The majority of existing cyclic stress-strain models for fiber reinforced polymer (FRP) confined concrete are applicable only to cases where post-peak strain hardening occurs. Cyclic model catering for strain softening is rare due to the lack of sufficient experimental data. Recent experimental tests on FRP-confined concrete cylinders involving strain-softening have identified new factors that have a significant effect on the cyclic behavior. Through an analytical study, a newly defined parameter, the effective confinement rigidity, is found to be a key factor governing the cyclic softening and hardening. By including the additional key factors and using the latest database with more strain-softening cyclic stress-strain curves, a stress-strain model of FRP-confined concrete subjected to cyclic loading considering both post-peak hardening and softening is proposed. Compared with the existing models, the proposed model can predict the cyclic behavior of FRP-confined concrete with better accuracy.