Calibration of a discrete spherical tank model through a mechanical-equivalent mass-spring model

The analysis of fluid-structure interaction (FSI) in storage tanks is a fundamental aspect of structural design, particularly in spherical tanks used for water storage. Numerical methods implemented in finite element software are commonly employed to address this phenomenon. These methods are typically based on complex formulations that integrate fluid dynamics, providing detailed and accurate results. However, in structural design, engineers often prefer simplified models that adequately capture the essence of the problem without requiring complex simulations. This research aims to validate the modeling approach of FSI in spherical storage tanks using a mechanical-equivalent mass-spring model (MEMSM). The impulsive and convective components of the fluid were represented as lumped masses and springs whose stiffness is associated with the oscillation of the convective component. A perfectly fixed base was assumed, neglecting effects of soil-structure interaction (SSI), to remain consistent with experimental conditions used for validation. The model was validated by comparing the natural vibration frequencies, and the results indicate that the MEMSM model predicts these frequencies with a difference of 1.3% for the impulsive component and a maximum difference of 6.7% for the convective component. This result validates the proposed approach and underscores its main contribution: providing an alternative, efficient, and easily implementable tool for the dynamic analysis of spherical tanks, suitable for early stages of structural design without compromising accuracy.