axisymmetrical vibrations of Tanks—Numerical

Abstract

With few exceptions, current seismic design codes for ground‐based cylindrical tanks neglect the effect of vertical ground acceleration. Such motion can be transmitted, in a flexible tank, into radial pulsations of the tank wall resulting in additional stresses. A numerical study of the axisymmetrical dynamic characteristics of partly‐filled tanks is carried out. Natural frequencies and mode shapes are evaluated by means of a discretization scheme in which the shell is modeled by finite elements and the liquid region is treated analytically. The distribution of the hydrodynamic pressure along the inner surface of the shell as well as the distribution of shell stresses are displayed. For practical applications, a simplified formula is developed to calculate the fundamental natural frequency of full tanks.