Study On Seismic Isolation Performance Of Medium Span Bridges

Small and medium span bridges is a common form of bridge structures in bridge construction in China. Currently, The study for seismic isolation of such bridge type is not perfect. There is still no clear theoretical specification as a guide for Seismic Isolation Design of such bridge type, there must be some security risks if according to the traditional design methods. Seismic Isolation Design of bridge in the future is bound to have an increasingly important role, the paper analysed the performance of seismic isolation for such bridge type. The main contents are as follows :(1)Describes the seismic isolation bridge principles,characteristics and Summarizes the development status of seismic isolation at home and abroad as well as future trends. Summarizes the seismic isolation design method and principles and methods of seismic analysis of the finite element models and explains how to simulate different seismic isolation bearings.(2)Through the seismic isolation device( LRB, dampers) for parameter sensitivity analysis, we can draw bridge seismic isolation design seismic isolation device parameter variations on the bridge isolation effect of reducing the impact.(3)Through the different structure types( cylindrical pier and rectangular pier), different seismic isolation scheme( ordinary laminated rubber bearings, dampers with ordinary laminated rubber bearings used in combination, LRB, high damping rubber bearings, ball rubber bearings) combined 10 kinds of finite element model calculation, comparing the use of different power characteristics in the same seismic waves, the main beam displacement, displacement of pier, plastic hinge regional variations, and the force of the below of the pier.(4)Through the LRB, high damping rubber bearings, ball bearing all the three seismic isolation devices were established in three different forms of high pier structures, such as equal pier height, unequal pier height but symmetry pier, unequal pier height pier from no symmetry. In contrast to the same seismic isolation scheme, pier height of change on seismic isolation effect. we can research the law by comparison of the characteristics of the cycle, displacement, plastic rotation, internal forces, such as the dynamic response of the pier end results under the same seismic force.