Stability Calculation And Relevant Parametric Analysis For CFST Arch Bridge

In recent years, CFST arch bridge has flourished in China. According to incomplete statistics, the deadline for the end of 2007, there are more than 200 seats CFST (concrete-filled steel tube) arch bridges including buildiing and under construction, of which there are 34 seats longer than 200m. However, the theoretical study on design calculation for such arch bridge lags behind the development of the practice. In this paper, to systematic study the relevant stability theory of CFST arch bridge and stability affect parameters , the finite elment method were used.(1) The research development of CFST Arch Bridge and its stability theory was summarized. The theory of nonlinear materials, pipe initial stress theory, and theory of the initial defect and the constitutive model of CFST were focused on. At the same time, the elements, principles and methods of stability analysis for CFST arch bridge with large-scale finite element software-ANSYS were introduced , and the foundation for stability of CFST arch bridge with ANSYS was laid.(2) In considering the geometric nonlinear, kinds of material nonlinear, or double nonlinear premise, a single-element method and double-element method, ANSYS FE software was used to calculate the ultimate load (UL) and ultimate displacement (UD) for two pilot CFST (single tube ) single-rib arch. A comparative with the experimental results was study, several constitutive relation theory models for core concrete and the adaptive for kinds of modeling methods were assessed, and the selection principles of accurate simulation and analysis with various methods for UBS (ultimate bearing state) for CFST arch were Made.(3) The Influence axiom for UL of circular CFST arch was obtained by analysis for impact parameters such as initial defect, initial stress, steel grade, steel ratios, concrete strength rating, load eccentricity, slenderness ratios, rise to span ratios, loading condition and element density and so on. Based on which a theoretical basis for optimization design of CFST Arch Bridge was provided.(4) Based on an actual bridge's stability impact parameters analysis, the result showed the following conclusions: the stability of the bridge in the design is conservative, steel pipe initial stress is greater impact on the stability for this CFST arch bridge. In the design of long-span CFST arch bridge, a non-symmetrical load should be designed as calculation control conditions, controlled the cross-ratio about 0.3 to 0.35, and controlled the UL impact by initial stress below 10%.