Finite element method of concrete-filled stiffened square steel tubes subjected to axial load

Concrete-filled square steel tubes have many advantages, they can be applied in the high and super high-rise building. If their width-thickness ratio exceeds a reasonable limit, local bucking is more likely to occur when they are subjected to compressive load, and that reduces the bearing capacity of concrete-filled square steel tubes. In order to improve the stability of the composite columns, longitudinal stiffeners are welded on the inner surfaces of steel tubes(called concrete-filled stiffened square steel tubes). In this paper, load-deformation relationship curves of concrete-filled stiffened square steel tubes subjected to axial compression load were analyzed by finite element software, and the calculated results were compared with experimental data. It can be seen from the comparison that with the increasing of width-thickness ratio of steel tubes, the finite element analysis overestimated the bearing capacity of unstiffened columns; the stability of steel tubes was obviously improved with the increasing of depth-to-thickness of stiffeners; welding one longitudinal stiffener on each inner face of steel tubes was a good stiffening method for the composite columns with large width-thickness ratio; for the ones with larger width-thickness ratio, more longitudinal stiffeners are better.