Experimental and numerical study on square RACFST members under lateral impact loading

•Square RACFST specimens under lateral impact loading•Experimental performance of laterally impacted square RACFST specimens•FEA simulation of square RACFST members under lateral impact loading

In this paper, experimental and numerical studies were carried out to investigate the performance of recycled aggregate concrete (RAC) filled square steel tubular members under lateral impact loading. A total of eleven specimens, including eight RAC filled steel tubular (RACFST) specimens and three normal concrete filled steel tubular (CFST) counterparts, were tested using drop-weight impact test rigs with fixed boundary conditions at both ends. The parameters studied were: recycled coarse aggregate (RA) replacement ratio, axial compressive load ratio and height of the drop-weight. The failure mode and local damages of the specimens were extensively investigated. The experimental results show that square RACFST specimens have the almost equivalent lateral impact resistance as normal CFST counterparts. Failure mode of steel tube is commonly indentation at the impacted area and buckling at the compression side of the section near the mid-span and the supports. Cracking under tension as well as crushed under compression of core concrete are observed at the mid-span and the location near the supports. A finite element analysis (FEA) model was also developed for simulating the performance of square RACFST members under lateral impact loading, and the predicted responses using the FEA model were in good agreement with the experimental results.