Diseño y evaluación sísmica de un tanque metálico de almacenamiento de 700 m³ considerando interacción fluido–estructura

Abstract

Steel water storage tanks constitute essential infrastructure within industrial facilities, particularly when they form part of fire protection systems, where their proper performance is critical before, during, and after the occurrence of a seismic event. In regions of significant seismic hazard, the structural or functional failure of such systems can lead to severe consequences, not only due to the loss of the stored resource but also because of the impact on facility safety, operational continuity, and personnel protection. Despite their importance, in professional practice the seismic analysis of storage tanks is often carried out using simplified approaches, without explicitly considering fluid–structure interaction effects or the actual conditions of the foundation soil. During a seismic event, the fluid contained within the tank does not behave as a rigid mass acting integrally with the structure, but rather interacts dynamically with the tank walls, generating additional hydrodynamic pressures and distinct vibration modes. This behavior gives rise to impulsive and convective components of the fluid motion, which significantly influence the global seismic response of the tank, particularly in terms of lateral forces, overturning moments, and foundation stability. Neglecting these effects may lead to inaccurate estimates of seismic demands, thereby compromising the structural performance and safety of the system under design-level earthquakes. In addition, the geotechnical conditions of the site represent a critical factor in the seismic response of the tank. The foundation soil not only provides structural support but also actively participates in the transmission and amplification of seismic actions. Variability in its mechanical properties may result in differential settlements, stress concentrations, and changes in support conditions, which become more critical under dynamic loading. In storage tanks, even moderate ground deformations can induce additional stresses in the steel shell and alter the distribution of contact pressures, adversely affecting the global stability of the system. Furthermore, soils with low shear strength, high compressibility, or unfavorable behavior under cyclic loading may experience stiffness degradation during seismic excitation, increasing the risk of sliding and overturning of the tank. In the case of saturated granular soils, the potential for liquefaction constitutes a particularly critical IV issue, as the reduction in effective soil strength may lead to excessive deformations, permanent displacements, or even a complete loss of structural support, regardless of adequate structural design of the tank. Within this context, the present research is justified by the need to develop an integrated seismic analysis of a 700 m³ steel water storage tank, explicitly incorporating fluid–structure interaction effects and considering the foundation soil conditions. By applying the equivalent dynamic model proposed by Housner and adopted by international standards such as API 650, the impulsive and convective components of the fluid response and their associated seismic demands are evaluated. In addition, the global stability of the system is verified through checks for overturning, sliding, and foundation contact pressures, considering both full-tank conditions and scenarios with minimum water levels. In this manner, the research contributes to reducing the uncertainty associated with the seismic design of storage tanks, providing a coherent and applicable technical methodology that enhances structural safety, system reliability, and informed decision-making in the design of critical industrial infrastructure located in seismic regions Keywords: Design, sismic evaluation, tank