Seismic Performance and Control of Elevated Liquid Storage Tanks with Negative Stiffness and Inerter-Based Dampers
Naqeeb Ul Islam, R. S. Jangid
Abstract
This study presents the application of a novel negative stiffness and inerter damper (NSID) for structural response control of reinforced concrete (RC) elevated liquid storage tanks (LST). The innovative NSID combines the advantages of the two mechanical devices by concurrently combining negative stiffness dampers (NSD) and inerter mechanisms. A multi-degree-of-freedom staging system with a two-mass lumped model (sloshing and rigid masses) for the liquid-filled container is used to model the RC-elevated LST. The stiffness constants associated with these lumped masses are calculated based on the tank wall and liquid mass parameters. The governing equations for the elevated LST model with NSIDs are derived and represented in state-space form. Time history analysis is carried out under near-fault (NF) and far-field (FF) earthquake records to investigate the performance of NSIDs as supplemental dampers. The most effective NSID parameters are found by optimizing them using a parametric analysis. Three different design scenarios based on different placements of NSIDs along the height of an elevated LST are presented. The overturning moment, base shear, rigid mass accelerations, and sloshing displacements are the objective parameters for evaluating the seismic performance and control efficiency of the NSIDs. Numerical studies show that the optimum NSID utilizes a minimum dashpot coefficient and effectively reduces the structural response quantities. In particular, the controlled LST shows a maximum 61.8% reduction in overturning moment compared to uncontrolled LST, which is a considerable decrease.