Seismic Responses of a Cable-Stayed Bridge to Spatially Varying Ground Motions

Abstract eng:
A random vibration methodology is formulated for the seismic analysis of cable-stayed bridges subjected to spatially varying ground motions. The ground motion spatial variability consists of the wave passage, incoherence and site-response effects. It is shown that all these effects have significant influences on the seismic response of the structure. The bridge investigated in this paper is a 7-span composite concrete-steel cable-stayed bridge. The overall length of the bridge is 1150 m, with a central span of 720 m between its two towers. The towers are Y-shaped reinforced concrete structures, with a height of 233.8 m. The bridge deck consists of three independent box girders. The central one is a closed steel box girder with streamline shape, and the two side spans are concrete box girders. The width and height of the deck are 30 m and 3.5 m, respectively. The cables are arranged in a double-plane fan type. Each cable plane has 23 pairs of cables. These cables are anchored to the deck at a 15 m interval on the main span and an 8 m interval on the side spans. For the large uncertainties in the specification of earthquake ground motions, it is inevitable to conduct parametric studies to determine the range of variability of the structures responses. The method used in this paper is quite efficient and convenient for such analyses.

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