Effect of tuned mass dampers on seismic fragility of piping system in nuclear power plant – Integrating experiment and finite element analysis

Abstract

Nuclear power plants encompass complex piping systems, which play a critical role in both operation and maintenance. With the occurrence of various beyond design earthquakes worldwide, there is an increasing necessity to enhance the seismic safety of the key components. Tuned Mass Dampers (TMDs) have gained prominence as an effective strategy for improving the seismic performance of piping systems. Existing studies on TMDs have primarily focused on evaluating their performance based on the reduction of system responses, such as displacement and acceleration, at locations where these responses are maximized. However, in actual nuclear power plant structures, the seismic evaluation of piping system is typically assessed through fragility analysis, and most piping systems are more susceptible to localized damage at connection points, such as elbows and T-joints, rather than at points of the maximum response. This study investigates the effectiveness of TMDs under various seismic loadings and assesses their impact on the seismic fragility curves of piping systems. To achieve this, an extended numerical experiment is conducted, developing a numerical model of a full-scale piping system that was validated against experimental results. Additionally, we examined the ability of TMDs to mitigate various local piping responses under high-intensity earthquakes which are challenging to address experimentally. Finally, fragility analyses are performed using several previously proposed TMD design methods, evaluating the influence of TMDs on the seismic fragility curves of the piping system.