Research On Unitary Stability Of Large Span CFST Arch Bridge

The CFST X-type arches improve the lateral stability by sloping the arc ribs so it is ofen used in the designs of CFST arch bridge with small ratio of the width to the span. Yesanhe bridge is a half-through CFST arch bridges, the design of yesanhe bridge can be used for reference of adopting CFST X-type arches in the design of arch bridges with small ratio of the width to the span.The software Ansys6.1 is used to analysis the stability of the state after construction of yesanhe bridge. In order to consider the nonlinear behavior of material, the stress-strain relationship of concrete filled steel-tube structure is introduced in the following research. The analysis result shows that the stability factor of the bridge deceased significantly when the nonlinear behavior of material is considered.Stability coefficient of large span CFST arch bridge is less than that of considering the geometrical nonlinearity, its numerical value decreases approximate 12%; Stability coefficient of large span CFST arch bridge taking into account geometrical nonlinearity and material nonlinearity is smallest, and the numerical value is about 45% of elastic stability coefficient. Therefore collective action of geometrical nonlinearity and material nonfnearity must be considered in computing the stability coefficient of the large span CFST arch bridge.Linear method is used in analyzing the finite element model of the bridge, the coeffient of stability of different state after construction is given. On the basis, the effect of different factors such as the sloping angle of arch ribs, the stiffness of bridge deck system, the effect of non-orientedly conservative loadings of the hanger and tie bar etc is discussed. The different coefficients of stability of changing these factors are given, so the factors that are vital to the lateral stability of X-type arches are found, and the rationality of the methods taken to enhance the lateral stability of yesanhe bridge is evaluated.On basis of summarizing the characteristics and virtues of the design ofyesanhe bridge, the effect of different factors to the CFST X-type arches is given in the end of the paper,its useful for reference to the readers who engage in bridge design.