Spatial Stability Analysis Of Double X-arch Bridge

Double X-arch bridge is a new type of arch bridge, which is developed on the basis of X-arch bridge. This type of bridge, with novel and artistic structure, unique shape and wide deck, is made up of two vertical arch ribs and two inclined arch ribs, and it highlights the spatial stress characteristic of superstructure. Because there is no lateral brace between two vertical arch ribs, lateral stiffness weakened will influence the stability of bridge and the stability becomes the key problem in design of Double X-arch bridge. Therefore, analysis on the stability of Double X-arch bridge has important theoretic meaning and engineering practical value.At present, there are not much research on the stability of Double X-arch bridge, and most of that are elastic stability analysis. This paper takes Yangmei Bridge with 100m span as an example and builds the finite element model in ANSYS for analysis. It also analyses the stable ultimate load-carrying capacity of this bridge with 3 methods(linearity, geometrical nonlinearity, material nonlinearity and geometric nonlinearity).Through comparative analysis, conclusion of this paper are as following:1. The buckling mode of Double X-arch bridge is out-of-plane buckling, so we must pay enough attention to lateral stiffness in practice.2. In general, transverse wind load has little influence on the stability of this bridge and its wind-resistance stability is good.3. Different load distribution on bridge deck has little influence on the stability of this bridge. Under nonsymmetrical loading, stability factor is not decreased.4. Through comparing stability factor gained by linear elastic analysis with that gained by geometrical nonlinear analysis, the difference is found to be within 2%.5. The stability factor gained by material and geometrical nonlinear analysis is 50%~55% of that gained by linear elastic analysis, only the material and geometrical nonlinear analysis can assess the stable ultimate load-carrying capacity of this bridge accurately.6. Under the action of surface load (3.5kN/m2)on bridge deck, the stability factor gained by linear elastic analysis is 6.7877 and that gained by material and geometrical nonlinear analysis is 3.5012, so we can draw a conclusion that this bridge is safe in stability.