Study on stability of concrete-filled dumbbell-shaped steel tubular middle long columns under axial load

In order to establish the calculating formula of stability capacity which can reflect the influences of more parameters of concrete-filled dumbbell-shaped steel tubular middle long columns under axial load,ABAQUS was used to establish the 3D finite element analysis model and to analyze the behavior of concrete-filled dumbbell-shaped steel tubular middle long columns under axial load.Based on the appropriate constitutive models and the experimental verification,parametric analysis was conducted to investigate the influences of the slenderness ratio,concrete strength,yield of steel strength and steel ratio on stability coefficient of concrete-filled dumbbell-shaped steel tubular middle long columns under axial load.The results show that the stability coefficient is obviously influenced by slenderness ratio and steel ratio,and hardly influenced by concrete strength and yield of steel strength.Based on regression analysis,a calculating formula of stability capacity suitable for concrete-filled dumbbell-shaped steel tubular middle long columns under axially loaded was suggested.The finite element analysis and experimental results are in good agreement.