In order to solve the problem that the contradiction between pier bottom internal force and girder displacement in the seismic isolation design of continuous bridges with high pier and long span, a seismic isolation system by combining friction pendulum system and brace is proposed based on the structural characteristics of braced-continuous bridge and the idea of energy dissipation, which can realize the double control of pier bottom internal forces and girder displacement. The equivalent damping ratio calculation formula of the brace is derived and the superiority of the combined use of friction pendulum system and brace is verified by contrastively investigating the seismic response of four isolation case. Finally, parameter analysis is carried out for brace, and the advantages in statics of the additional brace are also analyzed. The study results show that the equivalent damping ratio of the brace is 9%, the hogging moment of the fulcrum of the continuous bridge in the static aspect is reduced by 27%, the maximum reduction rate of the pier bottom moment is 79%, the maximum reduction rate of the pier bottom shear force is 83%, and the maximum reduction rate of the girder displacement is 50%. The combined use of friction pendulum system and brace can restrict pier bottom bending moment and girder displacement, and reduce the static and dynamic response of large span continuous bridges effectively.
Key words
continuous bridges /
high pier and long span /
double control of force and displacement /
seismic isolation
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References
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