Analysis Of Seismic Traveling Wave Effect On Multi-span Continuous Isolated Bridge

Since the bridge structures generally span somehow large, the pier bottom basetypes and soil conditions around are quite different, and also, surely there aredifferences when seismic waves arrive at the surface through different paths anddifferent geological conditions, the seismic waves of each pier bottom are different.It is necessary to consider the impact of non-uniform input vibration while conductingthe analysis of bridge structure seismic response; what’s more, traveling wave effect isthe main cause of ground motion spatial variation. On the basis of previous studies,this paper is concerning on the study of isolated bridge’s traveling wave effect asdifferent parameters change.The main research contents are as follows:(1) The researches on seismic response of the bridge under traveling waveearthquake excitation are reviewed, based on the comprehensive reading andunderstanding of related literature home and abroad.(2) A motion equation under traveling wave earthquake excitation on the isolatedbridge is deduced in the form of absolute displacement and using the progressiveintegration of isolated bridge by incremental motion equations for solving.(3) Analyzed the basic principles of the isolated bridge, and described theisolation of bridge structure design scheme and method in details, on this basis,carried an isolation design of a six span continuous girder bridge and made a finiteelement analysis of the isolation bridge.(4) An analytical study is conducted to evaluate the seismic traveling wave effectof a multi-span continuous isolated girder bridges under the input of longitudinalwave in the earthquake. The effects of some parameters such as the apparent velocity,the height of the pier, earthquake input dimension, and the type of the bearing areinvestigated.(5) Take the multi-span continuous isolated bridge as the research subject,according to the reduced rule of the model bridge is simulated earthquake shakingtable test research, compared the seismic response of the bridge model under the uniform excitation and traveling wave non-uniform input, verify the correctness of theresults of theoretical analysis, and the reliable experimental data and conclusions areobtained.Through the study on the six-span continuous isolation bridge of the travelingwave effect parameters, there were the discoveries that the traveling wave effect candecay the deck acceleration and the forces reaction of pier bottom, it is good to takingthe action of traveling waves for isolated bridges; the greater the apparent velocity ofthe ground motion, the greater the response of each pier internal forces, the internalforce more unfavorable reaction; shorter the pier, the greater the stiffness of the pier,Redistribution caused by the traveling wave effect is more obvious. Compared withthe traditional fixed bearing seismic bridge, it is more obvious attenuation of thetraveling wave effect for the lead rubber bearing (LRB) isolated bridge.