Damping capability enhancement of the polyurethane seismic isolation device for HV post insulators and its numerical evaluation with the 2023 Kahramanmaraş, Türkiye Earthquake Sequence

One of the most effective methods of improving high-voltage (HV) porcelain insulator earthquake performance is seismic isolation. A low-cost seismic isolation device consisting of polyurethane springs has been developed previously to ensure the seismic safety of porcelain insulators. In this study, a supplementary steel damper mechanism was designed to improve the damping properties of the device. Quasi-static tests were conducted to determine the contribution of the proposed mechanism to the system characteristics, such as additional stiffness and damping. An extensive shaking table test program was carried out on a post-insulator system with and without base isolation to investigate the global dynamic behavior of the system while subjected to seismic excitation. Ten historical earthquake records matched with the required response spectrum of IEEE693-2018 were applied, and the experimental results were used to validate the finite element model. The effects of the proposed damping mechanism on the seismic isolation system were investigated experimentally and numerically. The effectiveness of the seismic isolation device with additional damping mechanisms has been assessed for a case study of the 6 February 2023 Kahramanmaraş (Pazarcık M7.7 and Elbistan M7.6) Earthquakes.