| Concrete-filled steel tubular tied arch bridge is widely used because of its beautiful appearance,large span,reasonable stress and simple construction.With the development of arch bridge and the increase of span,the ratio of width to span is gradually reduced,and the problem of stability is increasingly prominent;with the increase of train speed,the dynamic characteristics of bridge structure affect the safety and comfort of driving.Therefore,this paper takes the 128 m tied arch bridge in Yinchuan South super large bridge of yinwu passenger dedicated line as the background,and analyzes the stability of the arch bridge and the dynamic response of the bridge structure under the action of high-speed train load.The main work is as follows:(1)In this paper,firstly,the theory of arch bridge stability and dynamic analysis is systematically expounded by consulting the data and domestic and foreign literature;After that,Midas civil is used to establish the finite element model of 128 m concrete-filled steel tubular tied arch bridge and analyze the stability of concrete-filled steel tubular in the construction stage.It is concluded that the stability coefficient gradually decreases from the pouring of arch rib concrete to the second stage of pavement dead load,but both meet the requirements of linear elastic stability coefficient greater than 4~5,indicating that the stability meets the requirements in the construction stage.(2)The linear elastic stability of the whole bridge under five working conditions is analyzed,which meets the requirements.Under the load of condition I(dead load + full span of two trains),the stability coefficient is 7.91,which is 21.3% less than that of the completed bridge.It shows that the characteristic value is related to the pressure level.The larger the pressure is,the smaller the stability coefficient is.(3)After analyzing the stability of arch bridge considering geometric nonlinearity,it is concluded that the stability coefficient of Arch Bridge Considering Geometric initial defect is reduced,and the larger the geometric initial defect is,the smaller the stability safety coefficient is.Therefore,when making,installing and transporting the arch rib,it is necessary to make the axis of arch rib conform to the theoretical line.(4)Based on the analysis of the influence parameters of the stability,the influence of the rise span ratio,the type of transverse brace and the non directional force of the suspender on the stability of the arch bridge is analyzed.The conclusion is that with the rise of the rise span ratio,the stability coefficient first increases and then decreases;the type of transverse brace has an influence on the stability,and the stability is better when the "K" type transverse brace and the "m" type transverse brace are used;for the through type arch bridge,the stability of the bottom type arch bridge is better when the Under the action of non directional force of suspender,the suspender tends to slow down the structural instability.(5)The dynamic response analysis of moving train load passing through the bridge at 250km/h ~ 350km/h shows that the amplification effect of arch bridge displacement and internal force increases with the increase of vehicle speed.The vertical acceleration increases with the increase of train speed,indicating that the greater the train speed is,the more obvious the dynamic effect is.(6)According to the dynamic performance evaluation of the bridge when the train passes through the bridge from the vertical deflection and vertical acceleration in the middle of the bridge span,the rigidity and vertical acceleration of the beam body meet the requirements under the design speed according to the corresponding specifications of our country;the beam body is safe. |
