Experimental investigation into mild steel circular concrete-filled double skin steel tube columns

Abstract

Constructing the concrete-filled double skin steel tube (CFDST) column involves placing concrete in between two steel tubes. Such tubes may have the same cross-section shape on the inside and outside, or they may have different cross-section shapes, as in the case of a square outer tube and a square inner tube, a circular outer tube, and a square inner tube, or a square outer tube and a circular inner tube, etc. In this article, the response of concrete-filled double-skinned steel tube columns (CFDST) to axial load is experimentally investigated. To create the CFDST column, two concentric mild steel circular tubes were filled with concrete. CFDST column behavior was illustrated using typical curves of axial load vs deformation and axial load versus longitudinal strain in the outer steel tube, inner steel tube, and concrete core. To further explore how changing the column's geometry and materials can affect its ultimate strength, parametric research was carried out. In the end, the experimental results were compared to the requirements specified in codes like Eurocode-4, AISC-360, ACI, and the equation given by Han et al. (2009).