Xiangtan City, Xiangjiang Bridge Dynamic Characteristics And Seismic Performance Study

The main bridge of the fourth Xiangjiang River Bridge in Xiangtan is cable-style flying swallow type concrete-filled steel tubulartired rod arch bridge with the total span of 120+400+120m. The stay-cable is anchoraged at the main arch directly which constitutes the new combination system bridge that the main arch bears force chiefly and the cable-style play the subsidiary role.The present thesis explores the Seismic Response:1,The present thesis is to analyze the self-vibration characteristics of the structure and obtain the first ten natural frequencies and modes as well as to make further exploration on some factors of structure self-vibration characteristics, such as the number and position of the transverse, stiffness of the main arch and tower, arrangement of stay cable , prestress , soil spring with the spatial girder finite element model of the main bridge of the fourth Xiangjiang River Bridge by Ansys.2,The present thesis is to obtain and compare the internal force response of the pirotal sections of the fourth Xiangjiang River Bridge through Response Spectrum analysis on different conditions.3,According to the Response Spectrum fitting method,direct method and Hao&OLliveria method of building the artificial seismic wave the Fortran program was compiled to generate the single point drive and multi-point drive artificial seismic wave for the fourth Xiangjiang River Bridge .The author put forward to the shortcoming of the Response Spectrum fitting at the same time and modified the artificial seismic wave generated through the minin mean square speed method.4,The present thesis is to obtain the internal force response of the pirotal sections by the time history analysis method with the artificial seismic wave corrected on different conditions as well as to make further discussion the effection of the time history analysis method and and the Response Spectrum analysis. 5,The present thesis is to obtain and compare the multi-point drive the internal force response of the pirotal sections by the time history analysis method on the condition of geometric nonlinear.6,The author give an evaluation to the seismic behavior of the fourth Xiangjiang River Bridge colligating the result of all kind of condition.