Clutching inertial system for base-isolated liquid storage tanks: Seismic performance and optimal parameters

Liquid storage tanks (LSTs) are susceptible to significant damage during earthquake events, necessitating their continued functionality and additional protection through isolation techniques. The sloshing response and overall base shear of LSTs are critical factors, particularly in base isolated (BI) tanks. This study aims to enhance the seismic resilience of LSTs by leveraging a newly developed advanced inerter-based vibration control methodology for structures. This innovative approach integrates a supplemental clutching inertial system (CIS) with a laminated rubber isolator (LRB). Utilizing an equivalent linearization technique, the study evaluates the equivalent damping and inertance constants to account for the nonlinear behavior of the CIS. These equivalent parameters are then used to assess the stationary peak response of the isolated tank structure, which encompasses sloshing and bearing displacements, forces within the CIS and the isolator, and the total base shear. Further, the analysis employs the stationary power spectral density function (PSDF) model of earthquake excitation by KanaiTajimi and the performance of the inerter-based hybrid control strategy is examined by varying system parameters, such as isolation period, isolation damping, CIS inertance mass ratio, and the tank's aspect ratio (i.e., broad or slender). An optimal inertance of the CIS is identified, leading to the least overall base shear for both isolated tank configurations. The impact of these parameters inertance mass ratio of the CIS is also investigated. Subsequently, the isolated tanks are exposed to eleven near-fault (NF) and far-field (FF) real-time earthquake excitations. The study evaluates the CIS's performance as an auxiliary system during these seismic events and contrasts the outcomes with the seismic response under stochastic excitations. The results highlight the effectiveness of the advanced inerter-based hybrid control strategy in reducing the seismic response of isolated tank configurations.