Analytical behavior of CFDST stub columns with external stainless steel tubes under axial compression

Concrete-filled double skin steel tubular (CFDST) stub columns with external stainless steel and internal carbon steel tubes can be considered as new types of composite members and expected to combine the advantages of all three kinds of materials. This paper presents non-linear finite element (FE) analysis and design of circular and square CFDST stub columns with external stainless steel under axial compression. FE models are developed, where non-linear material property of stainless steel is considered, and verified through comparisons with experiments in terms of failure modes, load-deformation histories and ultimate strength. Behaviors of stainless steel composite columns are compared with that of columns with both carbon steel tubes. Parametric studies are conducted to investigate the influence of the outer stainless steel tube strength, concrete strength, inner carbon steel tube strength and hollow ratio on structural behavior of axially loaded columns in terms of loading and interaction performance.