Analysis Of Seismic Response For Cable-stayed Bridge With Soil-Pile-Super Structure Dynamic Interaction

The earthquake is a kind of serious natural disaster. When earthquake occur, bridges are always damaged and traffic lines are cut off in the earthquake region, causing huge difficulty for rescue, secondary disasters aggravate, and huge economic losse. With the high-speed development of the urbanization and the economy, the construction of the bridge projects in China is developing rapidly. cable-stayed bridges are widely used in the long span highway bridge systems, so it is signality to study the seismic respond of the cable-stayed bridge.At present, the structural anti-seismic design is generally based on the assumption that the ground is rigid and the ground motion in nearby free field is used as the shaking input. If the structure is established on the bedrock or solid ground, this assumption is reasonable. However, if the structure is established on the soft foundation, the seismic respond of it will be changed by the interaction between the foundation and the super structure. The seismic respond based on the rigid ground assumption will cause an unreasonable result. Therefore this paper analysis the seismic respond of cable-stayed bridge with soil-pile-supers tructure dynamic interaction. The conclutions may provide some useful references of the seismic fortification cable-stayed bridge for the designers, constructors and managers .This paper takes a proposed large span cable-stayed bridge as the study object. Establishes a finite element analysis model of the soil-pile-superstructure dynamic interaction. Analyzes the influences of the the initial structure state for bridge structure vibration modals. Discusses the influences of the damping ratio, the vibration mode combinations and the motivational pattern for the bridge structure seismic response. Comparas and analyzes the seismic response of the bridge structure of the uniform excitation and non-uniform excitationwith traveling wave effect under the E2 earthquake cases.The main conclusions are following: The vibration frequencies of soil-pile-super structure system are lower than the super structure system, but the changes of curves are trend to same, vibration modalsares are basically the same. The seismic horizontal displacements and bending moment responses of the tower of soil-pile-super structure system are higher than that of the super structure, but the shearing force responses are lower. The vertical displacement responses of girdders of soil-pile-super structure system are lower than the that of super structure, but bending moment responses are higher. The internal forces of cable of soil-pile-super structure system are higher than that of the super structure. With the traveling wave effect, the horizontal displacement responses of the tower of soil-pile-super structure system are lower than that of the super structure, but the vertical displacement responses of girders are higher.The shearing force responses of the tower and internal forces of cable of soil-pile-super structure system are decrease, but the bending moment responses of girders are increase.