Seismic Response Analysis And Isolation Study Of (40+64+64+40)m High-speed Railway Continuous Girder Bridge

Prestressed concrete continuous beam bridges are widely used in China's high-speed railway projects due to their large spanning capacity,good stress and good performance.When earthquakes occur,bridges are often severely damaged.China is a country with frequent earthquakes.So it is very necessary to analyze and study the seismic response of continuous beams and control the vibration.In this paper,different types of seismic isolation bearings are introduced into a four-span continuous beam bridge,and the finite element model of the Zheng Wan high-speed railway(40+64+64+40)m prestressed concrete continuous beam bridge is established by Midas Civil 2019 software.The displacement and internal force response of the bridge under four different support conditions are studied.The main contents are as follows:(1)The research status of seismic analysis of continuous beam bridges is described,and the working principle of the bridge isolation and isolation system and four commonly used isolation and isolation bearings are introduced.(2)Establish a finite element model of prestressed concrete continuous beams under four support conditions,namely model A using spherical steel bearings,model B using lead rubber bearings,model C using sliding friction bearings,and using Model D of the high-damping rubber bearing,and comparing and analyzing the natural frequency and period of the bridge structure under four different supporting conditions,and studying the influence of the bridge structure on its dynamic characteristics after using vibration-isolating bearings.(3)Under the action of frequent earthquakes,select the appropriate response spectrum according to the specifications,use the response spectrum analysis method to analyze the displacement and internal force responses of the four different supports,and perform the internal force and displacement responses of the continuous beam under different support conditions Contrast,analyze the seismic isolation and isolation efficiency of the three seismic isolation bearings in the bridge structure under the excitation of multiple earthquakes.(4)Under rare earthquakes,use Midas Building to select 5 appropriate seismic waves in the strong earthquake records,and use the time history response analysis method to calculate the continuous beams under four different support conditions under the one-dimensional earthquake action.Displacement and internal force responses,and comparative analysis of the results,to study the seismic response law of different seismic isolation bearings under rare earthquakes.(5)Under the rare earthquake,by rationally defining the position and length of the plastic hinge of the bridge pier,the Takeda tri-fold hysteresis model is used to analyze the plastic hinge state of the bridge,and the brake is applied under the rare earthquake The pier enters the second yielding state,and both the side pier and the secondary pier are in the elastic state.Under the action of the transverse bridge,only the 124 pier enters the first yielding state,and the rest are in the elastic state.The moment-rotation angle hysteresis curve at the bottom of the plastic hinged piers is drawn,and the shape of the curve is analyzed using the path movement rules of the Takeda tri-fold line hysteresis model.