Influence of lumped mass and rotary inertia on seismic isolated post equipment

Abstract

This paper addresses a need to lessen the effects of seismic activity on heavy functional components installed on the top of post electrical equipment. A theoretical model was developed based on a distributed parameter system considering the lumped mass and the moment of inertia. Finite element analysis and shaking table tests were carried out on an ultra-high-voltage (UHV) bypass switch (BPS) with wire rope and viscous dampers to validate the theoretical model. Parameters analysis on seismic responses and isolation optimization based on rotational nonlinear constraints were conducted. Results show that the seismic responses of moment and displacement showed a strong linear law with the increase of lumped mass, but the acceleration response had a nonlinear decreasing trend. Notably, the moment of inertia effects shows a trend of increasing and then decreasing on moment responses. The composite isolation of stiffness and viscous damping can reduce the seismic response of equipment. For optimization analysis of seismic isolation, the ratio between variations of viscous damping and rotational stiffness along the steepest descent line are selected as a criteria, which can be used to identify the most influential parameter. Parametric analysis provides the optimal parameters for the seismic isolation, which are recommended for target-oriented control in engineering design.