Seismic retrofit of spherical liquid storage tanks with energy dissipative devices

Abstract

Numerical studies on the seismic behavior of a typical spherical liquid storage tank, equipped with conventional braces or retrofitted with passive energy dissipation devices, are presented. Three energy dissipation systems, in the form of diagonal braces, are investigated: non-linear viscous dampers and buckling-restrained and friction struts. All numerical analyses are performed by means of a detailed finite element model, considering the exact geometry of the elevated steel tank structure, the fluid-structure interaction effects for an arbitrary level of fluid filling, as well as the non-linearities introduced by the various bracing systems. Representative results for base shear forces, vertical displacements of the fluid content due to sloshing and displacements at characteristic locations of the retrofitted spherical tank are presented. The benefits introduced by each of the dissipative bracing systems used in this study are identified and discussed in comparison to the dynamic characteristics and the seismic response of the original spherical tank, fitted with a conventional bracing system.