Dynamic Analysis Of Long-Span Pedestrian Suspension Bridge

Pedestrian suspension bridges are widely used in mountainous areas and some tourist attractions in the central and western regions because of their great spanning capacity,beautiful appearance,clear force,convenient construction and good economic coordination.Compared with the vehicle suspension bridge,the bridge structure has the characteristics of narrow deck,small dead load ratio,small stiffness and more flexible structure.With the increase of span,its dynamic characteristics are more obvious,especially the response of the bridge structure under earthquake excitation is prominent.Usually in engineering practice,in order to increase the structural stiffness and improve the wind stability of bridges,wind-resistant cables are applied.At present,the research on pedestrian suspension bridges with wind-resistant cables mainly focuses on the influence of wind-resistant cables on the static wind stability and dynamic characteristics of the superstructure,and seldom considers the influence of wind-resistant cables on seismic response.In order to study the dynamic characteristics and seismic response of long-span pedestrian suspension bridge,this paper takes Dajiangkou pedestrian suspension bridge in Xupu County as the engineering background to carry out the following research:(1)According to the structural design drawing of Dajiangkou pedestrian suspension bridge in Xupu County,the finite element model of the whole bridge is established by using the finite element analysis software Midas/Civil,and the dynamic characteristics of the bridge structure are analyzed by multiple Ritz vector method.The pile-soil interaction is considered in the analysis,and the vibration modes,natural frequencies and periods of the bridge structure are obtained after calculation.(2)The response spectrum analysis method is used to analyze the seismic response of the finite element model of the bridge input acceleration response spectrum according to five working conditions.The internal force and displacement responses of the key sections of the main girder and the main tower under the quadrature component earthquake are obtained.(3)Artificial seismic wave is generated by MATLAB software,and dynamic time history analysis method is selected.Artificial seismic wave is acted on the structure model.The seismic response of the main component section of bridge structure at any time in the time-history range is calculated by direct integration method.(4)Using Midas/Civil software,a finite element model without wind-resistant cable is established to calculate the dynamic characteristics of the bridge without wind-resistant cable model,and the dynamic characteristics of the bridge without wind-resistant cable model are compared with those with wind-resistant cable model to study the influence of wind-resistant cable on the dynamic characteristics and seismic response of long-span pedestrian suspension bridge.