Test results of six concrete-filled double-skin steel tubular(CFDST) stub columns are presented.Circular hollow sections(CHS) and square hollow sections(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,and 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 CFDST 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,whilst that with CHS inner and CHS outer shown the best ductility behaviour.
[2] Han L H,Tao Z,Zhao X L,Concrete-Filled Double Skin(SHS Outerand CHS Inner)Steel Tubular Beam-Columns[J].Thin-WallStructures,2004,42(9):1329-1355;
[3] Tao Z,Han L H,Zhao X L,Behaviour of Concrete-Filled Double Skin(CHSInner and CHS Outer)Steel Tubular Stub Columns and Beam-Columns[J].Journal of Constructional Steel Research,2004,60:1129-1158;
[6] Yang Y F,Han L H.Concrete-Filled Double-Skin Tubular ColumnsUnder Fire[J].Magazine of Concrete Research,2008,60(3):211-222;
[7] ISO-834.Fire-Resistance Tests-Elements of Building Construction-Part 1:General Requirements[S].International Organization forStandardization,Geneva,Switzerland,1999;
[8] Han L H,Huo J S.Concrete-Filled Hollow Structural Steel ColumnsAfter Exposure to ISO-834 Standard Fire[J].Journal of StructuralEngineering,ASCE,2003,129(1):68-78;
[9] Lie T T.Fire Resistance of Circular Steel Columns Filled with Bar-Reinforced Concrete[J].Journal of Structural Engineering,1994,120(5):1487-1509;
[10] Lie TT,Chabot M.AMethodto Predictthe Fire Resistance of CircularConcrete Filled HollowSteel Columns[J].Journal of Fire ProtectionEngineering,1990,2(4):111-126.