Mathematical model and results for seismicresponses of a nonlinear isolation system

The friction and viscous damping actions always cause nonlinear responses of a seismic isolation system under earthquakes. Their influence on the seismic responses needs investigation in detail. In order to analyze the effects of nonlinear phenomenon on the seismic isolation system, a mathematical model was built for such a nonlinear isolation system, and the nonlinear responses were calculated and analyzed. The numerical results indicate that an appropriate combination of spring, Coulomb friction and viscous damper is able to achieve an optimal seismic performance. The stiffness and natural period of system are significantly influenced by the friction action. Both the friction action and the viscous damping action can dissipate earthquake energy, and the optimal value of one depends on the value of the other in the seismic isolation system. All of the values of spring, Coulomb friction and viscous damper should be accurately evaluated before the design of seismic isolation system.