Residual Strength of Concrete-Filled Double-Skin Steel Tubular Stub Columns after Exposure to Fire

Test results of six concrete-filled double-skin steel tubular (CFDST) stub columns are presented in this paper. Circular hollow section (CHS) and square hollow section (SHS) were used to fabricate the inner and outer skins of the composite columns. The main parameters explored in this test programme were the section type (CHS inner and CHS outer, SHS inner and SHS outer, CHS inner and SHS outer) and whether or not exposure to fire. It was found that the strength of the CFDST columns decreased significantly after exposure to fire. However, the residual strength of these innovative columns was still comparable to that of conventional concrete-filled steel tubular columns. Of all the three types of sections with a same hollow section ratio, the one with CHS inner and SHS outer shown the highest residual strength.