Non-linear Analysis of Axially Loaded Octagonal CFDST Short Columns

Concrete Filled Double-skin Steel Tube (CFDST) is a form of composite column that consists of outer steel and an inner steel tube and the space between them is filled with concrete. The structural response of CFDST columns is significantly affected by the thickness of outer and inner steel tubes and the compressive strength of infilled concrete. Although many studies have been in the past to understand the effect of inner and outer tubes thickness on the axial compressive response of circular CFDST columns, no such study appears in the context of octagonal CFDST columns. In this paper, the thickness of both inner and outer tubes is varied. Their effect on axial compressive behavior of CFDST columns containing the concrete of different grades is numerically examined. The non-linear FE analysis of CFDST columns is performed using the ABAQUS. The study shows that axial strength and ductility of octagonal section CFDST columns are significantly influenced by steel tube thickness and the grade of sandwiched concrete. Moreover, the study highlights the importance of the proper selection of inner and outer tube thickness for the better axial response of CFDST columns.