Abstract: In the paper,according to the principle of the non-linear FEM,based on the fiber model of beam structure and the geometric and material non-linearity of the CFST structures,an approach is presented for the ultimate load capacity analysis of CFST structures with dumbbell sections.Then the limit loads of CFST columns with dumbbell section are computed,and the results verify the validity and accuracy of the proposed method.With the comparison of the limit loads of CFST columns under various influential parameters,slender proportionlimit load curves are obtained.

Key words: concrete-filled steeltubewith dumbbell sections； ultimate load； elasto-plastic analysis；