Seismic Response Analysis On (42.85+72+72+75+42.85)m Continuous Beam Bridge

Bridges are expensive and take a long time to build.If a bridge is damaged by an earthquake,the damage is incalculable.Therefore,it is necessary to analyze the seismic response of bridges.In this thesis,a(42.85+72+72+75+42.85)m prestressed concrete continuous girder bridge on the new Lianyungang-Zhenjiang railroad passenger dedicated line is used as the research object,and the finite element model is established using the finite element analysis software Midas Civil 2020,and the seismic response analysis of the continuous girder bridge is carried out using the response spectrum method and the time course analysis method,and the main work is as follows.(1)To analyze the dynamic characteristics of the established finite element model and study the trend of period and frequency under each order of modalities of the bridge.(2)Considering the two conditions with and without train load,the seismic load is applied to the down-bridge and cross-bridge directions of the finite element model using the response spectrum method,and the displacement of the key section of the main girder and the top of the pier as well as the internal force response of the pier bottom are analyzed.The effect of the train load on the seismic response of the bridge under seismic action is studied.(3)Under the conditions of multiple earthquakes,three seismic waves are selected in accordance with the code requirements,and the three seismic waves are applied to the down-bridge and cross-bridge directions of the finite element model using the time course analysis method,and the displacements of the key section of the main beam and the top of the pier,as well as the internal force response of the pier bottom are analyzed under the action of different seismic waves.(4)Under rare earthquake conditions,plastic hinges are established at the bottom of the piers,and the yield state of the plastic hinges of each pier under the seismic action in both directions is analyzed by using the time course analysis method.The effect of changing the reinforcement of vertical reinforcement and hoop reinforcement on the plastic hinge state of bridge piers is studied.It is concluded that the ductility of the bridge pier can be improved by increasing the reinforcement of the vertical reinforcement of the bridge pier.