Dynamic Characteristics And Seismic Response Analysis Of (25+100+25)m Mid Bearing Steel Box Girder Tied Arch Bridge

Steel box tied arch bridge is widely used in highway engineering and railway engineering due to its remarkable advantages such as high bearing capacity,large spanning capacity,and beautiful structural form.In recent years,with the increase in the number of steel box tied arch bridges in China and the frequent occurrence of catastrophic earthquakes,the issue of bridge damage has become increasingly prominent.Therefore,it is very important to study the dynamic characteristics,earthquake resistance and seismic isolation.This paper takes(25+100+25)m Bayannaoer middle bearing steel box tied arch bridge as the research object,and uses the finite element software Midas Civil to establish two kinds of finite element models for the general seismic design and seismic isolation design of the bridge.The dynamic characteristic analysis is carried out and seismic response analysis under the E1 and E2 earthquake excitation of the bridge are also carried out,mainly completed the following work:(1)The working mechanism of bridge earthquake damage and bridge isolation and isolation system was elaborated.The principle and method of the interaction between the pile and soil and the lead isolated rubber bearing in the key part of the simulation full bridge model are introduced.(2)Analysis of dynamic characteristics of middle bearing steel box tied arch bridge.The Midas Civil software is used to establish two seismic design models without shock isolation and seismic isolation,and the eigenvalue analysis is carried out,and the results are compared.(3)In order to optimize the dynamic characteristics of middle bearing steel box tied arch bridge,the influence of the four parameters of the arch rib,cross bracing,pile and soil interaction and the stiffness of the bridge deck system on the self vibration characteristics of the bridge structure is studied.(4)According to the site conditions,earthquake intensity and other control factors,the normalized response spectrum under the E1 earthquake was selected,analyze the response spectrum of two models with or without seismic isolation,and compare the internal force response and displacement response of key sections of the two models.Study on the isolation effect of lead isolated rubber bearing in the middle bearing steel box tied arch bridge under the excitation of E1 earthquake(5)Three reasonable seismic records were selected under E2 earthquake conditions,Time-history analysis was used to compare the responses of the two models under longitudinal,lateral and vertical earthquakes.The seismic isolation effect of rubber bearing with lead isolated in E2 earthquake is studied.