Study On The Earthquake-reduction And Seismic-isolation Design Method Of Continuous Beam Bridges

It is well known, in general, that the bridges are the hinge of transportation, which are heavily invested in, and have important influence on national economy. Once destroyed, they will lead to huge economic lose, in fluence earthquake disaster reduction and repair of disaster area heavily. So it is very important to study the motheds of seismic design. A new mothed of seismic design is corned into being, because the tradition motheds of seismic design have some shortages. It is very important to adopt the effective earthquake-reduction and seismic-isolation measure to insure the safety of the structures in earthquake.Presently, preferably effective earthquake-reduction and seismic-isolation devices, such as viscous damper, sliding-frictional bearings, Lead-rubber bearings and Lock-up device, have been applied in overseas bribges. But they have hardly been applied in Chinese bridges. Accorbing to this circs, combinig with north-bridge approach of Su-tong long-span bridge, which is studied seismic isolation, this paper has studied some relative research work as followings.First, a brief summarizing of the developing situation and the signifinance studying of the technique of seismic isolation are introduced. The characteristic and origin of the harmness of bridge structure is analyzed.The developing direction of its seismic design mothed and earthquake-reduction and seismic-isolation technique are depicted.Second, by the computer program SAP2000N, three-dimensional finite element model of the north-bridge approach of Su-tong long-span bridge is simulated. Simulated model is mostly emphasized on in the model, which should be the stiffness, mass and boundary condition of the bridge in the fact.Third, according to the characteristics of north approach of Su-tong large bridge, the schemes of installing earthquake-reduction and seismic-isolation devices of the common continuous bridge are ensured. By comparation of the reduction effection of them, the optimized earthquake-reduction and seismic-isolation schemes are recommended, and the installed schemes of the conmmon seismic isolation devices are optimized.Fourth, according to the characteristic of north approach Su-tong long-span bridge, the schemes of installing earthquake-reduction and seismic-isolation devices of the high-pier continuous bridge are ensured. By comparation of reduction effection of earthquake-reduction and seismic-isolation devices, the optimized seismic isolation schemes are recommended.Fifth, in this paper, the main design parameters of viscous damper and lead-rubber bearings are discussed. The earthquake-reduction effectiveness of the main design parameters of viscous damper and lead-rubber bearings are studied. The conclusions can be used as referenc to earthquake-reduction and seismic-isolation design of the large continuous bridge, At last, based on the conclutions, some suggestions about the design of the large continuous bridge are presented.