Numerical analysis of circular double-skin concrete-filled stainless steel tubular short columns under axial loading

Circular double-skin concrete-filled stainless-steel tubular (DCFSST) columns have the distinguishing feature of high resistance to corrosion so that they can be constructed by either normal concrete or seawater sea-sand based concrete without corrosion. The numerical study of circular short DCFSST columns is very limited. This paper presents the computational modeling and behavior of short DCFSST columns of circular sections loaded concentrically. A computational model is developed for simulating the structural behavior of concentrically loaded short circular DCFSST columns, taking into account the effects of the concrete confinement induced by the double stainless-steel skins and significant strain hardening of stainless steel. The accuracy of the computational modeling technique proposed herein is assessed by means of comparing computations with available experimental data. The verified computational method is utilized to investigate the significance of geometric configurations as well as material strengths on the structural performance of circular DCFSST columns. The applicability of the current design provisions for steel tubular columns filled with concrete to the design of circular DCFSST columns is evaluated by comparisons against experimental and numerical results on DCFSST columns. The comparative study shows that the present computational model and the design formula proposed by Liang predict well the ultimate strengths of short DCFSST columns composed of circular tubes. The codified design approaches in current design codes generally give conservative estimations of the strengths of circular DCFSST stub columns.