Seismic Demand Analysis of Steel Storage Tanks Under Generalised Ground Motion

Seismic behaviour of steel tanks for oil storage is relevant in the light of industrial risk assessment because collapse of these structures may trigger other catastrophic phenomena, as fires or explosions due to loss containment. Therefore, seismic assessment should be focussed on leakage-based limit states. Damages suffered by storage tanks under seismic actions are generally related to large axial compressive stresses that can induce shell buckling near the base and to large displacements of unanchored structures leading to detachment of piping, liquid. The present paper approaches the analysis of seismic response of sliding, non-uplifting, unanchored liquid storage tanks subject to three-dimensional ground motion. The algorithm to solve the equation of motion for a simplified tank’s model is proposed and a sample estimation of the seismic demand by incremental dynamic analysis is discussed.