Study On The Static And Stability Of High-pier Extradosed Cable-stayed Bridges

The extradosed cable-stayed bridge is characterized by low tower,rigid girder and centralized cable.Because of its excellent structural function and economy,the extradosed cable-stayed bridge has been rapidly developed and extensively applied recently around the world.By taking a high-pier long-span extradosed cable-stayed bridge-the Hongxi bridge under construction as engineering example,its static and stability behavior is investigated,by changing the design parameters,the influence of these design parameters on static and stability behaviors of the extradosed cable-stayed bridge is also studied,which provides a reference for structural design of the extradosed cable-stayed bridge in the future.Firstly,state of the art of the extradosed cable-stayed bridge is reviewed,and its development trend,the structural characteristics,mechanical properties and its research progress are discussed,and the existing problem and further research of extradosed cable-stayed bridge are put forward.Secondly,the finite element model is set up by using the finite element analysis software MIDAS/CIVIL,the static behavior at the stages of largest double cantilever,largest single cantilever,completion and service conditions is analyzed.Thirdly,the linear and geometric non-linear stability of the bridge at the stages of bare tower,largest double cantilever,largest single cantilever and service condition are analyzed.Lastly,parametric analysis of structural static and stability of extradosed cable-stayed bridge is conducted,and the effects of design parameters including the girder height,the main-side span ratio,the length of non-stayed segments,the tower height to span ratio,the size of the tower,the form of the tower,the form of cable arrangement and the size of the pier on the static and stability performance are investigated,and the reasonable values of design parameters are also discussed.The results show that:structural design scheme of HongXi bridge is reasonable,and the deflection and stress under the serviceability limit stage and the ultimate limit stage meet the requirements of design code.The bridge is more stable,largest double cantilever stage is the most unstable state,and the geometric nonlinearity has great influence on this condition.Since the extradosed cable-stayed bridge has a low tower,the change of tower design parameters has little influence on static behavior.However,the girder height,the main-side span ratio,the length of non-stayed segments and the tower height to span ratio have important affect on static behavior,and should be considered carefully.As for the stability,the high-pier extradosed cable-stayed bridge is mainly controlled by pier,increasing the pier size can improve structural stability.