Performance of circular CFDST members with external stainless steel tube under transverse impact loading

This paper presents an experimental and numerical study on the impact performance of circular concrete-filled double skin steel tubular (CFDST) members with external stainless steel tube. Austenitic 304 stainless steel was used for all the test specimens. Taguchi approach was employed for the parametric design of the experimental program. The testing parameters were the impact height, hollowness ratio and axial load level. 18 specimens were tested under transverse impact loading to obtain the failure patterns, the time histories of impact force and mid-span deflection, as well as the strain developments in the stainless steel tube. Finite element (FE) models were then established and verified against the test results, in which the strain rate effects of the stainless steel, the carbon steel and the infilled concrete were considered. The validated FE model was then employed to investigate the whole dynamic response of CFDST members with outer stainless steel tube subjected to impact. The impact resistance of the stainless composite member was also compared with that of the CFDST member with an external carbon steel tube.