Seismic response of the outer shell of a liquefied natural gas storage tank using a semi-analytical dynamic substructuring technique

This paper deals with the seismic response of the outer shell of a liquefied natural gas storage tank. The concrete shell is considered as three inhomogeneous subsystems, namely; a circular plate of varying thickness on an elastic foundation, a cylindrical wall and a spherical dome. The linear dynamic response of the complete system, subjected to a strong seismic ground motion, is derived in the frequency domain using a semi-analytical approach. The concept of frequency- and wavenumber-dependent dynamic spring stiffness is introduced for the exact satisfaction of the displacement continuity and force equilibrium at the interfaces between the three subsystems. The ground motion is described kinematically in the form of a Rayleigh wave propagating along the free surface of the soil. The influence of the Rayleigh wave speed and of the interference of the structural responses to the horizontal and the vertical seismic ground motion are examined for a particular case