Finite element analysis on axial loading behavior of stub columns of square concrete-filled steel tube with diagonal ribs

New type of concrete-filled steel tubular (CFST) columns with diagonal ribs was put forward to improve the confinement effect on the core concrete provided by the square steel tube and the mechanical properties of concrete-filled thin-walled steel tubular columns. And diagonal ribs were of the same length as the tube, which were welded on the adjacent edges of the steel tube at the three dividing point. The axial loading behavior of the stub columns were simulated based on the finite element software ABAQUS, considering the parameters including the existence of diagonal ribs, width-to-thickness ratio of the steel tube, concrete strength, thickness of the diagonal rib, steel strength, weld length between the steel tube and diagonal rib, size and interval of the hole in the diagonal ribs. The results show that the existence of diagonal ribs can increase the load-carrying capacity of the stub column by an average of 14.9%, enhance the confinement effect on the core concrete provided by the square steel tube, and especially improve the composite effect and axial load-carrying capacity of the stub columns with high width-to-thickness ratio significantly. The composite effect of the stub columns will be better and the materials will be efficiently used when thicker diagonal ribs are adopted.