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With the development of large span bridge in China, large concrete-filled steel tubular truss and laced column structures appear constantly. The joints of these structures are mostly circular concrete-filled steel tubular (CFST) joints, and become thin-walled joints because the diameter-thickness-ratio of the chord is very large. In order to solve the problem of lacking of the theoretical basis on the mechanical properties of concrete-filled thin-walled steel tubular (CFTST) joints, refined finite element analyses were performed using ANSYS. The influence of geometrical parameters and loading conditions were analyzed to find the inherent pattern. The results showed that the ultimate capacities of CFTST specimens were smaller than that of CFST specimens with the same brace geometry and the same chord diameter under axial tension, axial compression, and in-plane bending, and the failure modes of CFTST and CFST specimens were different under axial tension and in-plane bending, while were basically the same under axial compression, however, the concrete crushing failure only occurred in CFTST joints, and did not generally appeared in the CFST ones. So the design method of CFTST joints and the CFST joints should be different. This research can not only provide scientific basis for the design of CFTST joints, but also effectively promote the application of CFTST truss and laced column in bridges, and can promote the improvement and development of the design theory of thin-walled steel structures. |
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Keywords:steel-concrete composite structure, thin-walled steel tubular joints, failure mode, refined finite element simulation |
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