Concepedia

TLDR

The paper presents a method to analyze the earthquake response of deformable cylindrical liquid storage tanks. The method uses finite‑element derived free lateral vibrational modes combined with a boundary solution technique, emphasizing cos θ‑type modes, to compute tank responses to ground motions and compare deformable tanks with rigid ones. Vibration tests confirm the accuracy of the mode‑based approach, and numerical examples show how tank geometry and cos nθ‑type modes affect seismic response.

Abstract

A method for analyzing the earthquake response of deformable, cylindrical liquid storage tanks is presented. The method is based on superposition of the free lateral vibrational modes obtained by a finite-element approach and a boundary solution technique. The accuracy of such modes has been confirmed by vibration tests of full-scale tanks. Special attention is given to the cos θ-type modes for which there is a single cosine wave of deflection in the circumferential direction. The response of deformable tanks to known ground motions is then compared with that of similar rigid tanks to assess the influence of wall flexibility on their seismic behavior. In addition, detailed numerical examples are presented to illustrate the variation of the seismic response of two different classes of tanks, namely, “tall” and “broad” tanks. Finally, the significance of the cos nθ-type modes in the earthquake response analysis of irregular tanks is briefly discussed.