| Lead rubber bearing (LRB) has small horizontal resistance under creep loads, and its post-yield-stiffness reduces quickly under seismic excitations, while the hysteretic of lead core dissipates the seismic energy. Fluid viscous damper, which is speed-related energy dissipation device, could provide strong resilience and excellent position-limiting capability. Both of the devices above are widely used in seismic mitigation and isolation at present. In this paper, based on a highway multi-span continuous beam bridge under E2earthquake, longitudinal and transverse seismic response was obtained using time-history dynamic analysis. The work may provide some reference for similar seismic isolation design of highway equal section multi-span continuous bridge. The main work are as following:1. On the background of structure control technology at home and abroad, the working mechanism and suit condition of seismic isolation technique was systematically introduced. The influence on seismic response of several key factors was analyzed, such as the damping calculation method, seismic excitations input, pile-soil interaction, etc. Two major seismic isolation devices——LRB and fluid viscous dampers——were introduced, with a detailed summary of their common mechanical model.2. With regard to the transverse direction analysis, considering the two-way-coupling model of LRB, the bridge transverse seismic response was obtained, and the influence on seismic-reduction rate of LRB design factors was analyzed.3. As to the longitudinal direction analysis, LRB and nonlinear velocity-related fluid viscous damper were adopted respectively, to discuss the influence on seismic-reduction of their setting mode.4. For the longitudinal direction analysis, the combined use of LRB and fluid viscous damper was adopted and explored. Compared with other seismic-isolation results, the paper provides reference and suggestion for practical application.5. The influence on seismic-reduction rate of fluid viscous damper design factors was analyzed, then the least square method was adopted to fit the functional equation between the seismic response and the fluid viscous damper design factors. |
