Author(s)

A. Maekawa & K. Fujita

Abstract

This paper describes the vibration tests, in which sinusoidal wave excitations with large input are conducted to the scale model tank of a thin-walled cylindrical water storage tank, and the theoretical analysis on the vibratory behaviours which are observed during the vibration tests. Large input excitation tests are carried out, in which the test tank is excited intensively by sinusoidal waves of a resonance frequency. The response of the tank, which means beamtype vibration, is not excited in proportion to the input acceleration above a certain level. Since oval-type vibrations largely appear on the sidewall of the tank in the tests, the interaction of oval-type vibrations over beam-type vibrations is considered. Concerning the deformation of the sidewall of tank by the oval-type vibrations, it is found that a large decrease in the flexural rigidity reduces the response of beam-type vibrations. A nonlinear vibration model is proposed assuming the flexural rigidity depends on the amplitude of oval-type vibrations. The analysis using this model has a good agreement with the results of the tests. Thus, it is demonstrated both empirically and analytically that the response of beam-type vibrations is reduced and the resonance frequency of beam-type vibrations is lowered by the coupling with oval-type vibrations. Keywords: coupling, oval-type vibration, beam-type vibration, cylindrical water storage tank, response reduction, nonlinear vibration model. 1 Introduction A cylindrical water/fluid storage tank, widely used in various fields including power stations and chemical plants, must be designed to ensure a high level of seismic resistance [1, 2]. The recent trend of using a large water storage tank

Keywords

coupling, oval-type vibration, beam-type vibration, cylindrical water storage tank, response reduction, nonlinear vibration model.