Bi-linear Stability Analysis Of CFST Arch Bridge Based On Midas/Civil

CFST arch bridges are widely used in actual bridge structures due to their many advantages.In recent years,with the continuous increase of bridge span,its width-span ratio has gradually decreased,making the stability of CFST arch bridges gradually become the focus of everyone’s attention.This article takes a CFST arch bridge as the research object.Firstly,the development status,advantages and disadvantages and stability research status of CFST arch bridges at home and abroad are introduced.In the second chapter,it introduces two types of stability problems,finite element analysis methods,nonlinear equations solving methods and iterative convergence criteria.Secondly,based on the experimental results of related literature,I studied how to use Midas/Civil software to realize the method of nonlinear stability analysis of the structure of the rod system,compared the calculation accuracy of different analysis methods and studied the effect of initial defect size and mode on structural stability.Finally,a nonlinear stability analysis of the arch bridge of an actual project is carried out,including static stability analysis and dynamic stability analysis,and the influence of different factors on the stability of the arch bridge is discussed.The results show that: in the Midas/Civil software,the material nonlinear analysis of the bar structure can be realized through the static elasto-plastic analysis(Pushover)and the dynamic elasto-plastic analysis static method.When the fiber model is used to analysis the structure,the result is more accurate.The stability of the structure is greatly affected by the initial defects,which should be taken seriously in the actual engineering;the stability of the bridge is less affected by geometric nonlinearity,but is more affected by material nonlinearity.In actual projects,the influence of both on the structure should be considered at the same time;the stability factor of the structure gradually decreases with the decrease of the concrete grade,and gradually increases with the increase of the wall thickness of the steel tube;the lateral bending stiffness has the greatest impact on the stability of the structure.When it reaches a certain value,it is no longer economical to improve the stability of the arch rib by changing the lateral bending stiffness;lateral seismic loading has the greatest impact on the dynamic stability of the structure,and the dynamic stability of the structure will be affected by the initial defects,so it should be paid more attention to in actual engineering.