On the Seismic Response of Elevated Steel Water Tanks Using a Lever-Arm Steel Slit Damper

The seismic behavior of an above-ground steel liquid storage tank supported on steel columns and retrofitted with a compact lever-arm amplification mechanism combined with a steel slit damper (SSD) is investigated in this study. The lever-arm mechanism amplifies the relative displacements transmitted to the SSD, enabling efficient energy dissipation through a compact device. Both the conventional and the retrofitted tank are subjected to nonlinear time history analyses (NLTHA), with soil–structure interaction (SSI) explicitly incorporated into the numerical models. The comparison between the two configurations reveals that the retrofitted tank achieves notable reductions in column drift and hydrodynamic wall pressures. The conventional tank is found to be particularly susceptible under soft-soil conditions, while the lever-arm/SSD system demonstrates consistent mitigation performance across all examined soil profiles. The numerical results indicate that the proposed system not only minimizes structural damage but also achieves an average quantitative reduction of 26% in fluid sloshing wave heights compared to the conventional bare frame. These outcomes establish the proposed passive control scheme as a viable and effective retrofit strategy for the seismic upgrading of elevated steel liquid storage tanks at sites with diverse geotechnical characteristics.