Nonlinear sloshing response of cylindrical tanks subjected to earthquake ground motion

A numerical method is proposed for the seismic response analysis of cylindrical tanks accounting for nonlinear hydrodynamic effects. The equations of motion are transformed from the physical domain into a well-defined computational domain by means of a change of variable such that there is no need to remap the computational domain at each time step as the computation of the response progresses in time. The numerical solution is then obtained using finite differences in cylindrical coordinates. The numerical formulation is applied to study the response of cylindrical tanks subjected to ground motion records from the Mexico earthquake of September 19, 1985. The response is studied in terms of wave height on the liquid surface, and shear force and overturning moment at the base wall, and compared against the linear solution. The case of resonance under harmonic excitation is also analysed and discussed. Implications on considering nonlinear hydrodynamic effects are drawn for design purposes.