Seismic performance of FRP

The objective of this study is to investigate the seismic performance of fiber-reinforced polymer-reinforced concrete-filled thin-walled steel tube (CFTST). Twelve specimens with different fiber-reinforced polymer types (glass fiber-reinforced polymer and carbon fiber-reinforced polymer) and reinforcing modes were tested under constant axially compressive load and cyclic lateral load. The failure mode and lateral load versus displacement relationship for each specimen were recorded during testing. The strength, ductility, and energy dissipation capacity were analyzed accordingly. Further, a stress–strain relationship and a restoring force model of the fiber-reinforced polymer confining steel tube with local buckling were proposed. A hysteretic model for the fiber-reinforced polymer-reinforced CFTST was developed subsequently. The results indicate that the seismic performance of fiber-reinforced polymer-reinforced CFTST can be effectively improved by optimizing the fiber-reinforced polymer type and corresponding reinforcing scheme. Carbon fiber-reinforced polymer and glass fiber-reinforced polymer are suitable materials for the confinement and bending reinforcement of the column, respectively. The modeling results show the energy imported into the column is mainly dissipated by the thin-walled steel tube. The energy dissipation proportion of the steel tube, concrete core, and longitudinal fiber-reinforced polymer are >80%, 10%–20%, and <8%, respectively. The energy dissipation value of the steel tube can be improved more than 40% after effectively restraining the local buckling