Design And Application Of Combined Seismic Isolation Device In Cable-Stayed Bridges

Cable-stayed bridges are widely used in river-crossing and sea-crossing projects in China because of their beautiful appearance and large span capacity.Because the development of cable-stayed bridges is relatively short,the research on the seismic response and isolation design method of cable-stayed bridges is not perfect.In order to study the seismic isolation effect of combined isolation devices in cable-stayed bridges,the dynamic performance and seismic response of the bridges are studied by using lead rubber isolation bearings,viscous dampers and Lock-up devices,taking the double-tower cable-stayed bridge of South Navigation Span of Zhoudai Bridge as an example.The results show that the combined isolation devices can effectively improve the stress condition of the bridge structure,and are appropriate.Restricting the longitudinal displacement of the bridge can achieve better seismic isolation effect.The contents of this paper are as follows:(1)Combining with the literature,this paper summarizes the current development of cable-stayed bridges,expounds the characteristics of cable-stayed bridges and the limitations of the current seismic isolation design of cable-stayed bridges,and introduces the research progress of common seismic isolation devices.(2)The mechanism and mathematical simulation methods of three kinds of isolation devices,lead rubber bearing,viscous damper and Lock-up device,are introduced in detail.This paper introduces the general situation of Zhoudai Bridge South Navigation Hole Cable-stayed Bridge,including the size information of each part of the cable-stayed bridge,the use of materials and modeling methods.Midas finite element software is used to simulate the whole bridge and calculate the natural vibration period and frequency of the cable-stayed bridge.The first ten modes and mode shapes are listed.(3)Three classical seismic waves are selected.After adjusting the seismic waves according to the code,the time history analysis method is used to analyze the cable-stayed bridge,calculate the peak values of internal forces and displacements in the key parts of the cable-stayed bridge,and compare the responses of the bridge structure under three seismic waves,so as to determine the seismic wave which has the most adverse effect on the cable-stayed bridge as the seismic load input in the seismic analysis.?(4)The main control parameters of the three isolation devices are analyzed,and the seismic response of the bridge after using the isolation devices alone is studied,and the rule of the effect of isolation and isolation varying with the parameters is obtained.(5)Three kinds of isolation devices are combined to compare and analyze the influence of different combination schemes of the combined isolation devices on the seismic performance of bridges.Through the analysis,it can be seen that the combined use of threekinds of isolation devices has better effect than one or two combination schemes of isolation devices.Composite isolation devices are beneficial to improve the seismic performance of cable-stayed bridges.