Rocking response of liquid-filled cylindrical tanks

The hydrodynamic response of liquid-filled storage tanks subjected to translational earthquake shaking has been the focus of studies for more than 75 years. In service, tanks experience six components of seismic input, with rocking due to support flexibility and/or rotational components of ground motion. Published theory for predicting hydrodynamic responses in rigid cylindrical tanks due to rotational seismic input is examined. Analytical solutions for pressure in the fluid and on the tank wall, and base moment are modified to account for the effects of angular displacements at the base. A finite element model of a water-filled cylindrical tank using the Arbitrary Lagrangian and Eulerian (ALE) solver in LS-DYNA is used to demonstrate the efficacy of the proposed expressions for three base rocking motions. Results from the modified analytical solutions and the finite element model are in excellent agreement.