Seismic performance of concrete columns reinforced with hybrid shape memory alloy (SMA) and fiber reinforced polymer (FRP) bars

Lack of corrosion resistance of structural steel has resulted in many structural failures. Fiber reinforced polymer (FRP) bar is emerging as a viable solution to replace steel to mitigate corrosion problems. Since FRP is a brittle material, it can bring about catastrophic sudden structural failures. Conversely, post-earthquake recovery of structures is another prime objective for performance based seismic design. Shape memory alloy (SMA) has the unique ability to undergo large inelastic deformation and regain its undeformed shape through stress removal. Here a hybrid reinforced concrete (RC) column configuration is presented in order to reduce permanent damages, and enhance its corrosion resistance capacity where the plastic hinge region will be reinforced with SMA or stainless steel and the remaining regions with FRP or stainless steel rebar. An analytical investigation has been carried out to develop such hybrid RC columns and analyze them under seismic loadings. The results are compared in terms of base shear-tip displacement, base shear demand/capacity ratio, ductility, residual displacement, and energy dissipation capacity to those of a similar RC column reinforced with stainless steel. The results indicate that such corrosion resistant hybridized column can substantially reduce the residual displacement with adequate energy dissipation capacity during earthquakes.

► Different hybrid configuration of column reinforcement.
► Determination of load-slip and moment rotation relationship due to slippage.
► Mitigation of problems associated with reinforcement corrosion and seismic loading.
► Hybrid FRP–SMA RC column can provide sufficient ductility and energy dissipation capacity.