An Experimental Study on Nonlinear Response of Concrete Filled Steel Tubular Copmposite Columns under Axial Loading

Abstract

Concrete Filled Steel Tubular (CFST) composite columns have been used as bridge piers and columns in multistory buildings etc.. It is now widely accepted that concrete filled steel tubular composite columns are well suited as compression members in high-rise buildings, long span, heavy loading and seismic structures. However there are limitations to its applications mainly due to lack of design guidance. This paper deals with the confinement effects of concrete filled steel tubular composite column subjected to different axial loading conditions and the effect of slenderness. The columns were circular in cross-section with constant D/t and slenderness ratio varies from 3 to 12. The experimental study includes for the confinement effect that the axial load applying on the steel only, on the concrete core only and both the concrete and steel. The bond between the steel and internal core concrete was critical in determining the formation of local buckling. In slenderness effect when the slenderness ratio is very low the column fails due to yielding of the steel and crushing. When the slenderness ratio is large, the column fails by elastic buckling.