Behavior of Concrete Filled Double skin steel tubular Columns under Static Axial Compression Load

Abstract

Concrete Filled Double-Skinned Steel Tubular Columns CFDSST are composite columns consisting of two concentric circular steel tubes with concrete filler in between. This research studies the behavior of the CFDSST columns under axial compression load. An experimental program included the fabrication of scaled columns of (5) CFDSST specimens of an outer tube diameter of (114 mm), and length of (600 mm). Three of them have three different thicknesses of outer steel tube and two with different hollowness ratios subjected to axial compression load. Making use of its ability to flow under its self weight, Self Compacting Concrete (SCC) used as the filled concrete. The experimental test results were presented in terms of load displacement curves and the axial and hoop strains at mid height of the outer tubes. Effect of the outer steel tube thickness on the axial capacity was studied as well the effect of Hollowness ratio was taken into account in this study. It was found that the axial load carrying capacity increased as the thickness of the outer steel tube increased since the confinement pressure increased.