Optimizing seismic performance: Integrating friction dampers into spherical liquid tanks

This study addresses the vital challenge of ensuring the safe storage of Liquid Natural Gas (LNG) in spherical tanks during seismic events, focusing on the crucial balance between meeting seis- mic performance criteria and mitigating economic losses due to potential operational disrup- tions from necessary retrofitting efforts. In response to this challenge, we present a case study on retrofitting an LNG tank near the North Anatolian Fault (NAF) line of Türkiye. Through a com- prehensive seismic evaluation, this study reveals inadequacies in the existing case's compliance with seismic criteria. It suggests a remedy involving the increased stiffness of lateral force-resist- ing members coupled with the utilization of friction dampers. Following the proposed stiffness increase achieved through retrofitting, our approach is fundamental to exploring alternative damping mechanisms designed to enhance the steel column-brace support structure. One of the key design challenges is the unique dynamic behavior of LNG, especially its sloshing during earthquakes, which necessitates a comprehensive understanding of fluid-structure interaction for accurate modeling and analysis. Through a series of transient analyses incorporating actions, we evaluate the effectiveness of the proposed retrofitting measures on the structure. Our findings introduce a feasible and efficient retrofitting strategy, marked by minimal operational interrup- tion, primarily by avoiding the extensive demolition and reconstruction typically required.