Seismic Sloshing in a Horizontal Liquid Storage Tank

A horizontal water storage tank was analyzed for seismic shaking at the ITER Tokamak Complex in France. The objectives were to (a) estimate the seismic forces in the tank; (b) calculate the sloshing response of the tank; (c) determine if baffles are needed to control sloshing; and (d) evaluate the possibility of using a single fixed support in the longitudinal direction to allow free thermal expansion of the tank. An approximate conservative analysis predicted very high sloshing waves and seismic forces in the tank. The fluid–structure interaction in the tank showed that only about 28% of the liquid moves with the tank wall and generates seismic forces in the longitudinal direction. The remaining 72% of the liquid sloshes near the free surface and does not generate significant seismic forces. The sloshing wave is not high enough in the longitudinal direction as the fundamental sloshing mode is not excited because of its very low natural frequency. Hence, baffles are not needed to control sloshing. The seismic force is low enough for a single fixed support to resist the entire seismic force in the longitudinal direction.