Research On Seismic Response Analysis And Isolation Design Of Long-span Network Arch Bridge

The network arch bridge has the advantages of light and beautiful body,clear force transmission path,large span capacity and superior economic index.It is being gradually popularized in China.Due to the lack of systematic research on the earthquake resistance of the long-span the network arch bridge,it is necessary to carry out special researches on its dynamic performance and the design of seismic isolation design in the construction of major projects.Based on the project of the Yellow River Bridge on Qilu Avenue in Jinan,this thesis analyzes the dynamic characteristics and seismic responses of the long-span the network arch bridge,then designs and optimizes the seismic isolation system.The main results are listed as follows:(1)The methods of bridge anti-seismic analysis and the principle of seismic isolation design are introduced.Lastly,structural characteristics and seismic principles of commonly used seismic isolation devices are then summaried.Lastly,This thesis expounds the domestic and international situation in anti-seismic researches of the network arch bridge and figured out some existing problems.(2)Combined with a large span simple supported network arch bridge case,Midas/civil software is used to establish its three-dimensional dynamic analysis finite element model.After calculation,the dynamic characteristics of the bridge are obtained,which indicates that the external stiffness of the bridge deck is less than the in-plane stiffness.By comparing the dynamic characteristics of the tied arch bridge with different suspender arrangements,It is illustrated the network arch bridge has different static and dynamic behavior characteristics relative to Nielsen system and vertical suspender arch bridge.(3)The response spectrum method and elastic time history analysis method are used to calculate the seismic response of the bridge supported by ordinary steel bearings.The results of the two analysis methods are compared,which show that response spectrum method can not be used as a safe and conservative calculation method for long-span complex bridges.The relative motion method(RMM)is used to study the effect of traveling wave on the large-span network arch bridge,generally speaking,the influence of shear wave velocity on the internal force and displacement of the control section is adverse.The results of seismic response show that the relative displacement between pier and beam and adjacent span during strong earthquake is very obvious,which should be an important control factor in the design of seismic isolation system.(4)Combined seismic response characteristics of the long-span simple supported girder and arch combination system and the performance of seismic spherical steel bearing,FPS friction pendulum bearing and fluid viscous damper,this thesis assesses the seismic isolation efficiency of the three device applied to the multi span simple supported beam arch composite system separately or in combination,and some representative conclusions are obtained.