UNDERSTANDING THE CHARACTERISTICS OF BULGING BY USING VIBRATION TEST AND NUMERICAL FLUID FLOW ANALYSIS

Abstract

It was found by the damage survey of the Great East Japan Earthquake and the Kumamoto earthquake that many water tanks which had been designed and manufactured according to the latest standard was damaged due to sloshing and bulging phenomenon. Although there is a countermeasure against sloshing which causes vibration of water surface, no countermeasure against bulging which cause mainly vibration of structure. For that reason, this paper aims to grasp bulging characteristics by using vibration tests of acrylic rectangular water tank and numerical fluid flow analysis. This study reveals bulging phenomenon has different characteristics from sloshing. Concretely, comparing results of vibration tests and analysis confirms that bulging occurs in a relatively wide frequency range. Result of analysis indicates that high pressure is applied to the corners in the bulging, the center and contact part with the bottom of the side plate of the water tank, although sloshing damages the ceiling and the upper part of the side plate. The results suggest that we need to find a countermeasure against bulging in the water tank which is different from that against sloshing.