Experimental and numerical investigation of circular double-tube concrete-filled stainless steel tubular columns under cyclic loading

This paper presents a cyclic loading investigation on double-tube concrete-filled stainless steel tubular (CFSST) columns with circular outer stainless steel tube and circular inner carbon steel tube. A total of eight specimens were tested under constant axial compressive load and lateral cyclic loading. The main variables explored in the test are: (a) axial load level (0.046-0.56); (b) diameter ratio of inner tube to outer tube (0.36, 0.57); and (c) presence of inner concrete or not. A finite element (FE) model was then developed and the prediction of lateral load (P)-lateral displacement (Delta) curves agree well with the test results. Furthermore, effects of various parameters on the P-Delta curves of the double-tube CFSST columns were analyzed in comparison to the double-tube concrete-filled steel tubular (CFST) columns.