Investigation On Dynamic Characterristics And Vibration Control Of Large Span Arch Bridge

With the development of society and economy the increasing speed of city development,rely on the bridge of continuous improvement,the bridge structure is a very important traffic lifeline in the service period,if damaged in the earthquake,it will be a serious threat to human life and property,so the dynamic characteristics analysis and reducing vibration control(earthquake)of bridge structure are of great significance.In this paper,take the half-through steel box truss arch bridge with main span of 531 m as an example,the finite element analysis software ANSYS on the seismic response of the static and dynamic characteristics of the structure and control characteristics and damping are analyzed based on the main research work carried out.(1)Establish the finite element model of the bridge in operating state.Compared with only under gravity loads,analyze the change of structural stress distribution response and the deformation in horizontal and vertical direction in effect of temperature change and braking force.Analyze the dynamic characteristics of the structure,by extracting the modal frequencies and the corresponding modes,draw the conclusion of the stiffness distribution of the structure in each direction,and the number of the modal which has control effect on the seismic response of the structure.(2)From the three aspects of displacement of structure stress distribution,the direction and internal force of main arch chords,analyze the response of structure under the earthquake in E1 and E2 probability with the response spectrum analysis method adopted and the earthquake action in three directions considered,and the response changes of structure under different probabilistic seismic load,then provide a reliable basis for the analysis of earthquake.(3)Considering the three directions of earthquake action,as well as structural material nonlinearity and geometric nonlinearity,the E2 probabilistic seismic time history analysis is carried out for the structure.From the three aspects of acceleration,displacement response,and the changes of stress distribution of the key components of the main arch chord and the bridge deck,discuss the vibration characteristics of structural responses the causes of them.Based on the elastoplastic time history analysis of structure under super large earthquake,and the analysis of the plastic development of the structure,and the rationality of the structural design is preliminarily judged.(4)In order to prevent falling beam damage,take the horizontal displacement of the bridge deck as control target,control the seismic response of the structure with viscous dampers,from three aspects of acceleration,displacement and internal force response,analyze the effect of structural vibration with damper controlled.Discuss the effect of dampers’ installation position on the control function of structural responses,and the viscous dampers’ control mechanism of the responses of structure.The influence of damping factor and velocity index on the response control of structure is analyzed by taking the displacement and internal force of structure as control object.