A Joint Friction Damping Model for the Seismic Analysis of Multilayer Suspended Thyristor Valve: Numerical and Shaking Table Study

The displacement and acceleration response are the key parameters in the seismic evaluation and design of a multilayer suspended thyristor valve. Meanwhile, the Rayleigh damping model, although popular for buildings and bridges, may underestimate the acceleration responses due to the high damping ratio in high-frequency ranges, as the suspension structure is significantly affected by high-order modes. This study investigates the damping source of the multilayer suspended thyristor valve, a scale-down model was constructed to obtain the equivalent damping ratios of several modes under seismic inputs. As the friction in the joints, other than the aerodynamic force, is the primary source of damping, the friction model is proposed to describe the energy dissipation behavior under earthquakes. An analytical model is established to validate the accuracy of the proposed model, and a detailed finite element model is founded to investigate the influence of the friction model. The friction model can correctly estimate the high-frequency range response, it is recommended to use the friction model in seismic evaluation of acceleration response of suspended thyristor valves. In addition, the equivalent damping ratio decreases with the pulled distance in the snap-back test, so the pulled distance is recommended to be no less than the estimated peak seismic displacement response.