Influence on the seismic isolation performance of friction pendulum system when XY shear keys are sheared asynchronously

Abstract When the friction pendulum system and shear keys work together to resist the ground motion, which obliquely inputs (non 45°) to the bridge structure, the shear keys in XY direction will be sheared asynchronously, so that the friction pendulum system will have a violent changing direction curve movement on the sliding surface under the earthquake, and there is a strong plane friction coupling effect during this process. In view of this situation, this paper constructs a Spring-Viscous damping-Coulomb friction plane isolation system with XY shear keys, which realizes the detailed and accurate mechanical analysis under the plane friction coupling effect of friction pendulum system, and adopts self-programming to realize the calculation of the time history response. The results indicate that when XY shear keys are sheared asynchronously, on the one hand, it will change the motion state of system, caused the influence of the plane friction coupling, on the other hand, it will cause a sudden change of the structural acceleration at the moment of the shear key sheared. While the shearing force of XY shear keys is small, the plane friction coupling effect will play a leading role, which will reduce the maximum acceleration of the structure. Meanwhile, the plane friction coupling effect caused by XY sheared asynchronously will increase the maximum relative displacement of the structure, and this amplification effect needs to be more importantly considered in the design of structural seismic isolation when the PGA is small.