Axisymmetric Finite Element Analysis for Sloshing Response of Floating Roofs in Cylindrical Storage Tanks

Abstract

Floating roofs are widely used to prevent evaporation of the contents of large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to floating roofs due to liquid sloshing. Establishing the structural integrity of floating roofs subjected to sloshing is an urgent issue for the petrochemical and oil refining industries. The present paper proposes an axisymmetric finite element analysis for the sloshing response of floating roofs in cylindrical storage tanks. The hydrodynamic coupling of the fluid and the floating roof under seismic excitation is taken into consideration in the analysis. The fluid is assumed to be incompressible and inviscid, and the roof is assumed to be linear elastic. In addition, the sidewall and the bottom are assumed to be rigid. The theory for the finite element analysis, in which the behavior of the fluid is formulated in terms of dynamic pressure using the Eulerian approach, is proposed. The basic vibration characteristics of the floating roof, such as the natural frequencies and vibration modes, can be obtained from this analysis. These characteristics provide engineers with important information on the floating roof design.