Displacement-based seismic design of reinforced concrete corroded circular columns strengthened with hybrid FRP

A simple bilinear stress-strain model of fiber-reinforced polymer(FRP) confined concrete was used to analyze the approximate cross-sectional ductility of undamaged circular columns strengthened with hybrid FRP under seismic loads.The effect of reinforcement corrosion on the sectional ductility was considered by the loss of rebar cross-sectional area,the reduction of rebar's mechanical properties and the degradation of interface bonding between rebar and concrete.Then,a simple analytical model was established to estimate the ductility of potential plastic hinge regions.Finally,a non-iterative displacement-based seismic design program for reinforced concrete corroded columns strengthened with hybrid FRP was presented on the basis of the simple analytical model.