# Understanding the Seismic Resilience of Metallic Cylindrical Tanks Through Parametric Analysis
These methods use simplified mechanical analogies to represent the complex phenomena of fluid-structure interaction, based on solutions to the Laplace equation under specific boundary conditions, allowing for the calculation of hydrodynamic pressure distributions induced by seismic forces. This research focuses on assessing the seismic response of both rigid and flexible cylindrical steel tanks, specifically above-ground tanks that are fully anchored at their base with an open top, which is commonly used for water or other liquid storage. The primary goal of the study is to evaluate the hydrodynamic pressures exerted by the fluid on the tank walls due to seismic excitation, as these pressures are crucial for determining the tank's seismic response. The circumferential stresses in the tank shell are highly influenced by these hydrodynamic forces, and their accurate evaluation is essential. While mechanical models provided by international standards can calculate global response parameters such as shear and overturning moments at the base of the tank, they do not account for the circumferential stresses, which are vital for a comprehensive analysis of the tank's structural integrity. Cylindrical tanks are typically preferred over rectangular ones because of their ability to withstand large circumferential stresses due to their geometry. This study examines the effects of various parameters, such as the tank's aspect ratio \(H/R\) and wall flexibility, on seismic performance. To assess the accuracy of current code provisions for the seismic analysis and design of liquid-containing structures, the research compares numerical results with those proposed by existing design standards. Specifically, three international codes are analyzed and compared: the New Zealand NZSEE recommendations [33], the European code UNI EN 1998-4:2006 [34], and the American Water Works Association AWWA D100-05 standard [40]. However, before applying numerical techniques for design purposes, the accuracy of these methods must be validated against experimental data. For this purpose, a fully nonlinear fluid-structure interaction (FSI) model based on the Arbitrary Lagrangian-Eulerian (ALE) formulation of the liquid-structure finite element method is used. Two existing experimental studies of anchored tanks are utilized for model validation. Fluid motion is governed by the compressible Navier-Stokes equations, and both material and geometric nonlinearities are considered to accurately determine stress, strain, and pressure distributions throughout the tank. The study proposes a rigorous finite element model to capture the three-dimensional behavior of cylindrical tanks, including the sloshing behavior of the contained liquid. Given that the methods used by the three standards to assess hydrodynamic pressures vary, this research aims to evaluate their reliability by comparing the results obtained from advanced finite element analyses. The findings from this study will contribute valuable insights into the actual behavior of above-ground cylindrical tanks under seismic motions and offer recommendations for improving the accuracy of seismic analysis and design for these structures.