| "Fly-bird-type" special-shaped arch bridge has a beautiful shape, large span and reasonable force structure. Therefore, in recent years, this bridge has developed rapidly in China and has been widely used. Concrete-filled steel tube arch bridge has a high capacity, beautiful across ability, plasticity and toughness, construction convenient, effective and foundation of economic adaptability,etc.,it is a promising development of the bridge structure. With the increasing span, the stability of concrete-filled steel arch bridge has drawn increasing attention of engineers, it is necessary for stability analysis.For pressure-based long span arch bridge, the stability issues have always been key to the design problem. Only to get the correct simulation of the rib rigidity can has the real stability of this bridge. Combination of materials belonging to the steel tube, steel tube of concrete filled steel tube enhances the stability of the wall, while Steel tube has a confinement effect to core concrete, so it can improve the compressive strength of concrete, so the stiffness calculation of concrete-filled steel tube rib is complexity.Because the out-of-plane stiffness of single-ribbed arch bridge is weak, so the stability of single-ribbed arch bridge is particularly important. This article system discusses the stability computation theory, by means of finite element software ANSYS to establish the real bridge model based on the 102 State Road across Yitonghe River bridge, and select into four different stages of loading bridge conditions, analysis the elastic stability and nonlinear stability of this bridge, in order to get the stability factor of bridge in a variety of load conditions, and then compare stability factor of only consider the geometric nonlinear or material nonlinear with the stability factor consider of linear elastic stability analysis. And compare the result of stability factor when considering the dual nonlinear analysis with only considering linear elastic stability. Now commonly used linear elastic approach to stability analysis in bridge design and stability analysis, which may be obtained safety factor is too large, we try to use dual nonlinear stability analysis method, summarized the difference between the results obtained by different methods. Observe the form of buckling mode map by low-level failure modes for the same type of bridge design reference, as shown in the form of increased low-level unstable part of the stability of instability.On this basis, this paper also discusses various factors affecting the stability of arch bridge. Focused on discuss and research the roll angle of the rib, part of the boom failure, cross struts and braces, concrete strength of arch, stiffness of tie, span ratio and the stability of arch and other factors affect the stability. And get some useful conclusions. Live load of different ways of cloth containing the stability of arch through different loading conditions to be embodied. Partial load and the side span is usually contained in the most unfavorable distribution. Take one of horizontal brace or brace component failure in a full bridge to observe the changes in stability, also observe the effect stability of the whole bridge by removing one of boom simulated failure of individual boom. Observe the different stability of the whole bridge by changing the size of rib angle. Through change the grade of concrete filled steel tube arch to simulate the rib strength change on the stability impact of the whole bridge. Similarly, we use of contrast method analyze the different factors affect the stability of the arch bridge. The study result of this paper have the important significance and reference value for the design and build of concrete filled steel tube arch bridge.
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