Dynamic Characteristics And Aseismatic Behavior Of Long-span Composite Girder Cable-stayed Bridge

In this thesis, according to the design of construction drawing, Three dimensional finite element model of Yongjiang bridge, which is composite girder cable-stayed bridge with joint-tower and four-plane, is developed using general commercial software MIDAS/CIVIL 2006. Meanwhile, dynamic characteristics, seismic behavior and parameter optimization of Energy dissipation device of the long-span cable-stayed bridge are described.Firstly, an introductory review of seismic research status of bridges at home and abroad and seismic analysis method of long-span cable-stayed bridge is summarized. Engineering background and main research are described. Methods of finite element analysis of the bridge structures are also presented. Then, the free vibration modes and frequencies of the bridge are computed using the subspace iteration method. The effect on dynamic characteristics with or without pile-structure is compared. Next, linear spectrum response analysis and nonlinear time-history analysis of earthquake are applied to analyze seismic behavior of the structure; and the influence of wave-passage effect interaction to the seismic response of the bridge is considered. Analysis shows that the main bridge in the earthquake will have a greater longitudinal displacement, and should be controlled to ensure the seismic safety of bridge. Subsequently, the main design parameters of viscous dampers are described by nonlinear time-history analysis. Then the effect of damping constant and damping exponents on the seismic response of the structure are studied. It shows that, a reasonable choice of viscous dampers can respond to the structure reduction of both displacement and internal forces in the same time, and improve the cable-stayed bridge seismic capacity and durability. This can be used as reference for other bridges seismic analysis and earthquake-reduction design. Finally, based on the results obtained, some suggestions are presented about the design of viscous dampers in the long-span cable-stayed bridge.