Stability Analysis Of The Large Span Conctere-Filled Steel Tube Arch Bridge

With the rapid economic development,. The CFST is considered as the preferential structure material for many advantages such as reducing the materials and structure weight, easy construction and large bearing capacity etc. While, the CFST arch bridge is characterized as continous construction system changing, seriously non-linear influencing, highly coupling of the construction process and the bridge status in completed stage. So, it is most valuable to carry on the stability analysis. Based on the Nanning bridge, the stability analysis in each stage of the construction was carried on.(1)The basic stability theory and the computing theory of the arch bridge were introduced, considering the characteristics of the steel concrete arch bridge, the evaluaton index and failure criteria were presented as well as the failure modes of the bridge. the s incremental finite element methods were also dicussed.(2)Adopting the unified strain-stress model, the CFST were considered as one combined material. With the help of the ANSYS program, the steel concrete arch bridge was constructed with the beam188 element type.(3)The construction process of the steel concrete was complicated. Eccentric load induced by the pumped concrete in the steel pipe and the change of the stiffness influencing on the stability of the structure was large. The stability of the structure in each stage of the six pump plans were analyzed. The optimal sequence of the CFST was gained.(4)Based on the buckling analysis and the arc length controlled incremental finite elment methods, the linear elastic and elato-plastic stability of the bridge in the construction and finished stages were computed and analyzed. The first and second stability factors and failue modes were obtained. The non-linear features influencing on the stability of the bridge were analyzed. It was considered that initial geometry defects and non-liear material were major influencing factors. While, the non-linear geometry influencing on the stability factors was comparatively little. Considering the wind load influencing on the stability of the structure, the lateral stability of the structure was analyzed. While, the ratio of the wide and span influencing on the stability of the structure was analyzed as well as the stiffness of the arch rib and the cross arm. The range of the ratio of wide and span was presented, the failure mode of the structure in different stiffness of the arch rib was discussed as well as the crosss arm layout.