Study On The Influence Of PSI To Seismi Response Of Hybrid Girder Cable-Stayed Bridge With Single Tower

When it comes to the cable-stayed bridge,the hybrid girder cable-stayed bridge has been given special attention,not only for its most rapid development speed in the past twenty years,but also for it's becoming the peak and the future of the long-span and super-span cable-stayed bridge,although it was born late.The hybrid girder cable-stayed bridge owns a lot of unique properties,and has been widely built.There is something significant undoubtedly should be done to the theory progress of the seismic research and the engineering practice on this kind of bridge in the future,for example to carry out seismic response analysis,to study the laws of seismic responses,to explore the failure form and failure mechanism of the earthquake may occur.The analysis for the influence of pile-soil interaction to seismi response of hybrid girder cable-stayed bridge with single tower was done in this thesis,which was based on the existing research achievements on the seismic response of the long-span cable-stayed bridge and pile-soil-structure interaction?PSSI?of the structure by home and abroad reaseachers.The main research contents in this thesis are as follows:?1?The development process and structure characteristics of the hybrid girder cable-stayed bridge are summarized concisely,the research achievements on the seismic response of long-span cable-stayed bridge and pile-soil-structure interaction?PSSI?of the structure by domestic and foreign scholars are described briefly.?2?According to the second Hanjiang River Bridge being built in Yuekou on the Qianjiang Railway Branch Line,a hybrid girder cable-stayed bridge with single tower,two dynamic finite element calculation models are established by using midas Civil 2015,one is model I without considering pile-soil interaction?i.e.,model without piles?,another is model II that considered the pile-soil interaction?i.e.model with piles?.Then,the dynamic free vibration characteristics including effective mode participation coefficient in quality of the models are calculated via multiple Ritz vector method.According to the fortification level,site classification and soil type in site for the bridge,the standard design response spectra for the bridge are selected,and then the seismic response spectrum analysis of the models are carried out on five earthquake action cases considering two earthquake standards.?3?One earthquake wave named pel₉0_san that is the most consistent with the requirements for the bridge is selected with the method in relative specifications combining the site conditions.And the peak acceleration of the selected earthquake wave is adjusted to be equal to the peak acceleration of the response spectrum of the frequently and rarely occurred earthquake in the response spectrum analysis,then the adjusted earquake wave is taken as the ground motion input for the models,finally the time-history analysis of the seismic response of the models under uniform excitation mode on five earthquake action cases are carried out.?4?A comparative study on the maximum earthquake internal force response and maximum displacement response of structure control section or the control points of the models between the response spectrum analysis and the time-history analysis are carried out,then relevant conclusions are made: the calculation results with two methods comply with the specifications;the pile-soil interaction has significant effect to the seismic response of the hybrid girder cable-stayed bridge with single tower,which can not be ignored;one suggest is given that model with piles should be adopted in its seismic response analysis,considering the safety of bridge structure as far as possible.The achievements of this thesis can be used for the seismic response analysis and aseismic designof the same type bridge in the future.