Preliminary study on effectiveness of internal force and displacement dual-control seismic isolation system for high-pier long-span continuous beam bridge

Here, to solve the problem of contradiction between internal force at pier bottom and displacement at beam end in seismic isolation design of high-pier long-span continuous beam bridge, a seismic isolation system with dual-control of internal force at pier bottom and displacement at beam end with combination use of friction pendulum bearings and supports was proposed based on characteristics of support continuous beam structure and energy dissipation and seismic reduction ideas. The calculation formula for equivalent damping ratio of support structure was derived, and seismic responses of 4 seismic isolation schemes were studied contrastively to verify the superiority of combination use of friction pendulum and support structure. Parametric analysis was conducted for support structure, and advantages in static aspects of additional support structure were also analyzed. The results showed that when equivalent damping ratio of support is 9%, negative bending moment at support point of continuous beam in static aspects decreases by 27%; in dynamic aspects, the maximum seismic reduction rate of pier bottom bending moment is 79%, the maximum seismic reduction rate of pier bottom shear force is 83%, and the maximum seismic reduction rate of beam end displacement is 50%; combination use of friction pendulum bearings and support can effectively control internal force on pier bottom cross-section and displacement at beam end to reduce static and dynamic responses of long-span continuous beams. © 2023 Chinese Vibration Engineering Society. All rights reserved.