| Composite girder cable-stayed bridge is a cable-stayed bridge system which combines concrete bridge decks and steel beam, with its excellent mechanical behavior, widely used in the construction of the bridge. In this paper, the research object, Hekou Bridge, is a large-span composite girder cable-stayed bridge located in high intensity area. For analysis its seismic response under the different influence parameters, the main contents of this paper are as follows:(1) Summarized the present seismic response analysis methods of bridge, and described in detail of static method, spectrum method and time history analysis method which the basic principles, advantages and disadvantages.(2) Based on the theory of finite element, a spatial finite element model of Hekou Bridge has been established in MIDAS/CIVIL software. Considering pile-soil-structure interaction or not, the dynamic characteristics of two models has been analyzed. The results show that while considering pile-soil-structure interaction, the structural stiffness is reduced;. Dynamic characteristics analysis of the finite element model which has the different form of the tower-girder connection show that tower and beam consolidated to strengthen the structural rigidity, the primary frequency of the bridge is increased to 88%, which the shape of vibration mode changes.(3) Analysis on seismic response of composite girder cable-stayed bridge, include analysis on seismic response in different load cases by the uniform excitation time history method, and comparing to the response result of seismic excitation is inputted from unidirectional and combination of direction. Meanwhile, the paper discussed on seismic response of the maximum cantilever stage of composite girder cable-stayed bridge located in high intensity area.(4) For the influence of traveling wave on effect seismic response of structure, in this paper seismic waves with different velocity are used as the seismic input. Compared to the uniform excitation, analysis on the relationship of the change of wave velocity and the traveling wave effect is discussed.(5) By using time-history analysis, the influence of pile-soil-structure interaction, constraints between tower and beam, different damping calculation and modal numbers for structural seismic response of Hekou Bridge was analysed in detail, which provides reference for the seismic design of composite girder cable-stayed bridge. |
