Seismic behavior of large-scale FRP-recycled aggregate concrete-steel columns with shear connectors

The application of fiber-reinforced polymer (FRP) composites for the development of high-performance composite structural systems has received significant recent research attention. A composite of FRP-recycled aggregate concrete (RAC)-steel column (FRSC), consisting of an outer FRP tube, an inner steel tube and annular RAC filled between two tubes, is proposed herein to facilitate green disposal of demolished concrete and to improve the ductility of concrete columns for earthquake resistance. To better understand the seismic behavior of FRSCs, quasi-static tests of large-scale basalt FRSCs with shear connectors were conducted. The influence of the recycled coarse aggregate (RCA) replacement percentage, shear connectors and axial loading method on the lateral load and deformation capacity, energy dissipation and cumulative damage were analyzed to evaluate the seismic behavior of FRSCs. The test results show that FRSCs have good seismic behavior, which was evidenced by high lateral loads, excellent ductility and energy dissipation capacity, indicating RAC is applicable in FRSCs. Shear connectors can significantly postpone the steel buckling and increase the lateral loads of FRSCs, but weaken the deformation capacity and energy dissipation performance.