Stability And Dynamic Characteristics Analysis Of Single Rib Braces CFST Arch Bridge

The single rib braces CFST arch bridge is a new type of bridge in recent years, it is elegant appearance, novel structure, the construction is simple and rapid, on the bridge construction field have great development space. The Guangwu highway Shuangfeng to Pingtai is demonstration project of ministry of communications and Guangdong province, considering meet the highway general layout, the overpass plane,vertical,cross section uniform highway alignment, design unit adopt the new type on the k111+495 overpass.Thanks to the material strength improve, the CFST arch bridge stability is outstanding on the construction and complement state, and thanks to the enlarging span, the bridge dynamic characteristics increasingly outstanding, how to solve this problem using in being economy and technical condition became restriction this type development key factor.This article systematic introduce the arch stability and dynamic theory, use finite element software, take for Guangwu highway Shuangfeng to Pingtai k111+495 overpass example, analyze the bridge's stability and dynamic, this dissertation has dealt with the following respects:(1)On the basis of consideration of geometric nonlinearity and material nonlinearity, adopt steel tube concrete unified theory, analyze the construction state stability, the results show that the first-order coefficients of stability of the completed bridge cases decline 10% when consider geometric nonlinearity, when consider double nonlinearity, the statues of the completed bridge first-order coefficients of stability is decline 60%.(2)Adopt line elastic buckling method, analyze the complement state stability, the results show that, the first steps of instability character almost same, the first-order of structure instability character is arch rib out-surface symmetric buckling, bridge deck torsion, so can explain the bridge transverse stiffness weaker to vertical stiffness, easily occurred out-surface instability.(3)Adopt spatial iterative method, analysis and calculation the bridge first-ten order natural frequency, the results show that, the bridge out-surface stiffness is small, the out-surface vibration of the arch rib appears first in bridge vibration and there are 4 steps of out-surface vibration in first 10 step; its vertical stiffness is more greater than its out-surface stiffness.(4) Discuss the brace arrangement,connecting component,arch rib stiffness,rise-span ratio,width span ratio influence the bridge dynamic, the results show that, the brace can improve the bridge transverse stiffness and can prevent early appearance arch rib local instability situation; the change of compressive stiffness for concrete-filled steel tube have little influence to each vibration frequency, and the change of bending stiffness for concrete-filled steel tube have certain influence to each vibration frequency; rise-span ratio has great effect to the bridge dynamic, width span ratio has great influence only to bridge deck out-of plane stiffness.