Study On Seismic Energy Dissipation Of Curved Continuous Girder Bridge

The curved girder bridges have a widespread use in highway and city expressway overpass because of its linear fluent and beauty structure. But they are more susceptible be damaged in earthquake, as its asymmetrical layout. Therefore, to understand the seismic response specialty of curved girder bridges, the application of shock absorption device in curved girder bridges and many factors related to it, which has the important practical significance for the curved bridge anti-seismic design.In this paper, the author based on a curved continuous girder bridge, using ANSYS to set up the 3-D finite element model of the whole bridge, then add four shock absorption devices at radial and tangential direction of movable bearing. The four shock absorption devices are E-steel dampers, viscous dampers, friction pendulum bearing and Lead-Rubber-Bearing. Afterwards, the author input three different types of ground motions. Through the analyzed and compared this curved continuous girder bridge's seismic response under three ground motion, the author obtained some valuable conclusions:The selection of shock absorption device and its parameter is closely related to the dynamic characteristics of the curved girder bridges, the shock absorption device can set in radial and tangential direction of curved bridge and adapt to the arrangement of the bearings. Under the action of three typical ground motions with different spectrum composition (the Elcentro ground motion, the Tianjin ground motion and Northridge ground motion), these shock absorption devices have diffident shock absorption effect. After calculation, it can be seen that these four kinds of shock absorption devices have different sensitive degree of the spectrum, relatively speaking, the viscous damper has better shock absorption effect under all three ground motions, it is un-sensible to the spectrum composition, and it is applicable. Therefore, when designing damping devices we should consider of the vibration environment of the curved girder Bridges.Because of it has different joint stiffness between inside pier and outside pier with main girder, the seismic force of the inner pier and outside pier has great difference under ground motion, the inner one is greater than the outside one. After shock absorption devices are added, although the joint stiffness between the girder and pier is changed, which lead to the difference of degree decrease, the outside piers force of the bridge remained "small". In this paper, the viscous damper has the best shock absorption effect in the direction across the bridge under three ground motions. Secondly lead-rubber bearings, but it is sensitive to the spectrum composition of ground motion. E-steel damper and friction pendulum bearing almost has no contribution to shock absorption effect in the direction across the bridge.After add these four shock absorption devices, the seismic response of continuous curved girder bridge under three ground motions can rise and fall, that is when shock absorption device is added in reducing the key points, the seismic response of other parts will gained in different degrees, but in the referenced ground motion designing the shock absorption devices' dynamic parameters, the effect were well. Also, these four shock absorption devices can effectively reduced the bending moment and torsion of the piers, proof that they can reduce the bending and twisting coupling effect of curved continuous girder bridge.In this paper, on the basis of calculation and analysis the author concluded viscous damper can effectively reduce the seismic of this curve continuous girder bridge, is a kind of more superior applicable to the seismic energy dissipation of curved continuous girder bridge. For one is because it is not sensitive to the spectrum composition of ground motion, the other is it can effectively reduce seismic response of the key point, while in other parts the seismic response of non-key point are increasing littler.