Seismic Response Analysis On (60+100+60)m Continuous Beam Bridge Of Nanning-Chongzuo Railway

Bridge engineering is a national lifeline project.China has a vast territory,complex terrain,and traffic is mostly dependent on bridges.Railway bridges play an important role in economic development and disaster relief,especially prestressed concrete continuous girder bridges,which have the characteristics of safety,economy,large span and convenient construction.However,such bridges are self-weighting,and piers are prone to bending and shear failure during earthquakes.Therefore,it is necessary to study the seismic response and seismic isolation measures of prestressed concrete continuous girder bridge.In this thesis,the(60+100+60)m prestressed concrete continuous beam bridge of Chaoyang double-line bridge of Nanning-Chongzuo Railway is taken as the research object.The finite element software Midas Civil is used to establish the whole bridge model.The dynamic characteristics analysis,response spectrum analysis,time history analysis and parameter sensitivity analysis of friction pendulum isolation bearing are carried out.The main work are as follows :(1)Two models were established by Midas Civil 2021(whether the pile-soil interaction was considered)to study the period and frequency,and the dynamic characteristics of the two models were compared.(2)Using response spectrum analysis.The longitudinal and transverse earthquakes are applied to the two models respectively,and the train load conditions are analyzed respectively,and the responses of displacement and internal force are compared and analyzed.It is concluded that the bridge is in elastic working state under frequent earthquakes and the necessity of considering pile-soil interaction.(3)Using time history analysis.Under the action of frequent earthquakes,the seismic waves are selected and amplitude modulated according to the code.The selected three seismic waves are applied to the model considering the pile-soil interaction in the longitudinal and transverse directions of the bridge.The time history analysis is carried out and the displacement and internal force responses are studied.The response results are compared with the response spectrum analysis method.(4)Using time history analysis.Under the action of rare earthquake,the plastic hinge unit is established at the bottom of each pier,and the selected three seismic waves are amplitude modulated and input into the model.The time history analysis of the pier is carried out,and the development of the plastic hinge of each pier is analyzed.The influence of the reinforcement ratio and the stirrup ratio on the ductility of the pier is studied.It is found that increasing the vertical reinforcement ratio of the pier can improve the ductility of the pier.(5)Under the action of rare earthquakes along the bridge,the influence of the curvature radius and friction coefficient of the hyperbolic friction pendulum isolation bearing on the seismic isolation is studied.The seismic response of the friction pendulum isolation bearing and the spherical bearing is compared and analyzed.It is concluded that the friction pendulum bearing fully consumes the energy of the earthquake to the bridge structure.