Study On The Seismic Responses And Shock Absorption Technique Of Self-anchored Suspension Bridges

Concrete self-anchored suspension bridge, having a beautiful appearance, competitive in cost, is especially suitable for urban bridges. In recent years with the increasing of the span the demand of aseismic is becoming more important, so it is very necessary for us to research its dynamic property and its seismic response.The methods of establishing and solving of the dynamics equations were reviewed in this paper. Then a finite method analysis model of was built for a concrete self-anchored suspension bridge with a span of 180m—The Yellow River Rd. Bridge in ChaoYang City Liaoning Province. With the aids of a FEA programs, the first 100 natural frequencies and its according mode shape were obtained. The response spectrum analysis was performed to assess the seismic response primarily. Then an artificial wave was generated by adjusting a real seismic record. The time history analysis was performed and the results were compared to the spectrum analysis. It was found that the result is of spectrum analysis is larger then the time history analysis subjected to the longitudinal excitation.Earthquakes may induce pounding between the main girder and the towers. This paper discussed the basic assumptions, theories and methods of analyzing the pounding effects. The effects were evaluated in detail for the Yellow River Rd. Bridge. And the parameter analysis reveals that the pounding may increase or decrease the seismic response which is manly depend on the initial gap between the tower and the main girder.Without the need of external energy, viscous dampers can consume a large amount of energy during earthquakes, but not add any additional stiffness, and also allow the bridge's displacements due to temperature changes. It can be used as the preferred long-span bridges damping device. This paper presents the principles of choosing the viscous dampers on the main parameters. The influences of the viscous dampers placing between the main girder and the towers to the seismic responses and the impacts of pounding were studied. It was found that the longitudinal responses were reduced significantly but the decrease of the lateral responses was limited.