Behavior Of Concrete-Filled Double-Skin Steel Tubular Columns Under Local Compression

Concrete-filled double-skin steel tubular (CFDST) columns have almost all the same advantages as traditional concrete-filled steel tube (CFST) members. Moreover, they have lighter weight, higher bending stiffness, and better cyclic performance. It is also expected that CFDST columns will have higher fire resistance capacities than their CFST counterparts, due to the inner tubes of the former being protected effectively by the sandwiched concrete under fire condition.The paper experimentally and theoretically investigates the behavior and design method of CFDST columns subjected to local compression. The main works of this study can be summarized as follows:1) The studies on performance of CFDST members under full compression and locally loaded traditional CFST members were reviewed.2) Eleven CFDST with outer and inner steel tubes of circular hollow section (CHS) and eleven CFDST with outer and inner steel tubes of square hollow section (SHS) were tested, and the hollow ratio, thickness of the top endplate and partial compression area ratio were set to be the main parameters. The effects of the main parameters on the performance of CFDST columns were investigated.3) A finite element analysis (FEA) model was developed based on the software ABAQUS, and the failure models and the load versus deformation relations of CFDST columns under local compression were simulated. Generally, the predicted results agreed well with the tested results.4) Based on the analysis of the test data, the simplified formulae for the bearing capacity of CFDST columns under local compression were suggested.