| Dumbbell shaped concrete-filled steel tube has many advantages,such as beautiful appearance,large in-plane stiffness and good spanning ability.It can achieve good economic and social effects in practical application.According to statistics,the number of arch bridges with concrete-filled steel tubes as the arch ribs in the form of dumbbell shaped sections accounts for 43% of the completed arch bridges.Therefore,it is of great engineering significance to study the mechanical behavior of dumbbell shaped concrete-filled steel tube.At present,the experimental and theoretical research on dumbbell shaped CFST at home and abroad mainly focus on axial compression,pure bending and biasing,while the experimental and theoretical research on the compression-bending members of dumbbell shaped CFST are relatively few.Therefore,Experimental research and theoretical research on the stress-compression of dumbbell shaped CFST are necessary.In this paper,based on the compression-bending tests of 8 CFST members with different axial compression ratios(4 circular and 4 dumbbell shaped)completed by our research group,the mechanical properties of dumbbell shaped CFST compression-bending members are studied in the following aspects by using the FEM analysis software:1?Compression-bending tests of circular and dumbbell-shaped concrete filled steel tubular members are simulated by FEM analysis software.The failure state and calculation curve of finite element simulation are compared with the test results,and the finite element model is verified.2?The influence of different parameters(axial pressure ratio,slenderness ratio,concrete strength and steel tube strength)on the flexural capacity of circular and dumbbell shaped CFST compression-bending members under combined compression and bending loads is investigated by using the finite element method.It is found that all parameters have a greater impact on the flexural capacity of circular and dumbbell shaped CFST,but the influence rules are different.The flexural capacity increases with the increase of concrete strength and steel tube strength.As the slenderness ratio increases,it decreases,and as the axial pressure ratio increases,it first increases and then decreases.3?This paper explores the influence of different parameters(axial pressure ratio,slenderness ratio,concrete strength and steel tube strength)on the flexural rigidity of circular and dumbbell shaped CFST compression-bending members under combined compression and bending loads by using the finite element method.It is found that the flexural rigidity of circular and dumbbell shaped CFST at the elastic stage increases with the increase of the concrete strength,and its growth trend was approximately linear,but the flexural rigidity of the elastic-plastic and plastic stages decreases.Steel tube strength and slenderness ratio have almost no effect on the flexural rigidity of CFST with two sections at the elastic stage.Increasing the axial pressure ratio makes the flexural rigidity of the two types of CFST sections at the elastic stage first increase and then decrease.4?Based on the finite element parameter analysis of circular and dumbbell shaped CFST compression-bending members,combined with the existing literature on dumbbell shaped CFST,and referring to the existing formula of CFST compression-bending correlation curve,the formula of CFST compression-bending correlation curve suitable for dumbbell-shaped CFST is deduced. |
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