Analysis For Nonlinear Stabilities Of Concrete-Filled Steel Tubular Arch Bridges

Concrete-filled steel tubular(CFST) arch has been generally used in the bridge construction in past ten years. Its stability is the most importance element in construction and operation. The stability problem divides into two kinds generally of the elastic buckling and the elastic-plastic buckling. With span increasing and material strength enhancement, when reaching in-plane or out-of-plane buckling state the material in general enters the elastic-plastic deformation range and the resulting displacements are usually large. Therefore, as it concerns to CFST arch, the stability problem is that of double nonlinearity including material and geometric nonlinearity.In the construction process, often have very many initial flaws. It may has the influence to CFST arch bridge' s stability. Deflection of arch axial line is more common among the construction process. The sample in this paper shows that: arch axial line has had the deflection and the deflection has surpassed the standard permissible value.The paper introduce CFST arch bridge's development and present situation first. Base on the summary of the arches bridge' s advantage, the paper introduce the design theory and the current study of stability in details. Then elaborates the base way of CFST arch bridge' s stability analysis, and uses the stress-strain relationship of concrete filled steel-tube structure and the theory of large displacement and small deformation to analyze the material and geometric nonlinearity influence to the structure. At last, to set up four typical cases base on the survey of Taojiadu Bridge in Panzhihua which has had the deflection of arch axial line and to analyze its stability of elastic and elastic-plastic by ANSYS software.It is opportune and necessary to analize the stability of CFST arch bridge which has had deflection of arch axial line and the deflection has surpassed the standard permissible value. This paper not only has the theories signification but also has the reference value in engineering practice.