Site Conditions, Impact Analysis, The Dynamic Characteristics Of The Damping Bridge

In this paper, the development and present situation of vibration absorption technology and the application isolation device, especially the Lead-Rubber-Bearing (LRB) are introduced. The principle and design method of isolation bridges are present; the influence of site condition on seismic ground motion, the classification and characteristic of site condition, the input of seismic wave and soil-structure interaction are analyzed.The rationality of the structure model and element parameters was verified through the calculation of the example in reference. The changing pattern was present through calculating the damping ratio, rigidity, frequency and acceleration in soil layers under different site conditions and seismic inputs.Considering different site conditions, earthquake motion, shear wave velocity and different bearings by time history analysts the changing trends of decreasing amplitude ratio are studied through finite element method. Finally, it is concluded that: the performance of LRB is excellent under the first and second site conditions; its performance becomes worse under the third and forth site conditions, and the isolation ability can't be obtained when the shear wave velocity is dropped below 140 m/s. Other ways of decreasing seismic response of bridges should be taken.