Study On The Stability Of High Pier Longspan Low Tower Cable-stayed Bridge In Construction And Operation Stage

The Jinshajiang Low Pagoda Cable-stayed Bridge is currently the largest railway lowstayed cable-stayed bridge in China.It is located on the main stream of the Jinsha River 1.3km below the junction of the Jinsha River and the Yalong River in Panzhihua City,Sichuan Province.It is the key and difficult project and control project of the Chengdu-Kunming Railway capacity expansion and reconstruction project from Miyi to Panzhihua.This article takes the Jinsha River low-tower cable-stayed bridge as an example to carry out the work on the Jinsha River low-tower cable-stayed bridge.It measures stress,cable force,and elevation on the spot,applies finite element theory,and performs simulation analysis with the help of finite element software.On this basis,the stability of the bridge is analyzed.The work and conclusions of this article are as follows:(1)A finite element model was established to simulate and analyze the stability of the Jinsha River low-tower cable-stayed bridge during construction and operation.(2)The stability analysis of the highest pier and the largest cantilever section of the bridge is carried out,and the stability characteristic value obtained by the finite element software meets the stability requirements.(3)At each stage of the second tensioning of the stay cable,the operation of the completed bridge,the full load of the side span,the full load of the middle span,and the full load of the full bridge,the finite element software is used to simulate and analyze,and it is concluded that the stable characteristic values of each stage are greater than 4,satisfying Stability requirements.(4)Use the finite element model to perform linear and geometric nonlinear analysis,from which it can be concluded that the stable eigenvalues meet the stability requirements.In the linear and nonlinear analysis,the stability eigenvalue is not obviously affected by the geometric nonlinearity,so the geometric nonlinearity may not be considered in the stability analysis.(5)By calculating the cable-beam live load ratio,the cable-beam live load ratio is directly proportional to the cross-sectional area of the cable stay and is inversely proportional to the main beam stiffness;as the cable-beam live load ratio increases,the main beam spans mid-bend The moment and the bending moment at the fulcrum continue to decrease,while the bending moment at the bottom of the tower gradually increases,while the maximum deflection of the main beam and the top of the tower continue to decrease;the stability of the bridge structure is affected by the cross-sectional area of the stay cable and the concrete of the main beam The influence of strength level is very small;during the completion of the bridge,the cable-beam live load ratio has little effect on the stability of the bridge structure.