Numerical study on stiffened concrete-filled double steel tube square columns behaviour

Nowadays, more research has been done to investigate the behaviour of concrete filled double steel tube (CFDT) columns owing to the numerous advantages over concrete-filled steel tube (CFST) columns. Very few studies have focused on the behaviour of stiffened CFDT columns. This research gap is aimed to be covered in this paper, by studying the behaviour of CFDT columns under axial loads using different stiffener profiles that are welded to the inner and outer tubes. The performance of square-stiffened CFDT columns is investigated using the finite element (FE) method. Three types of stiffeners were studied: rectangular, inclined, and tie stiffeners. The verified FE model is used to study the effect of different parameters on the behaviour of stiffened CFDT columns. The results show that using tie stiffeners give the most increase in the ultimate axial load capacity by more than 15%. A simplified analytical model is presented to predict the axial load capacity of stiffened CFDT columns using tie stiffeners.