Cfst Arch Bridge Nonlinear Stability Analysis

The development history of the concrete-filled steel tube(CFST) arch bridges is more than ten years in our country, we are all surprised to its application range or increase in span. However, the calculation theory of CFST arch bridges need to be further lucubrated, the design criterion of CFST arch bridge is also being constituted.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 is bigger in the linear and elastic condition, while the value of the stability factor only decreased a little when taking into account geometrical nonlinearity. But when the geometrical nonlinearity and material nonlinearity are all considered, the value of the stability factor decreased approximate 50%. It also shows that the instability of CFST arch bridge almost happens in the plastic area, and stress of the instability is bigger than the high-point of the elastic stress. The stability factor will be very bigger if the linear method is used in analyzing the stability of the bridge. So the ultimate loading is exact only when we consider the geometrical nonlinearity and material nonlinearity.The effect of different factors such as the disposal of the lateral braces, the stiffness of the main arch-ring and deck construction, the effect of non-orientedly conservative loadings of the hanger is discussed, and the rationality of the methods taken to enhance to the lateral stability of this kind of bridge type is evaluated.