An innovative isolation system for improving the seismic behaviour of liquid storage tanks

The current study proposes a new vertical seismic isolation of an aboveground liquid storage tank (AST) and theoretically and numerically evaluates its effectiveness for a comprehensive practical range of tank geometries. In the proposed system, the forces in the vertical direction caused by the overturning moment are isolated as an alternative to the common horizontal system used for shear base isolation of ASTs. The equations of motion for a liquid tank equipped in the proposed system were extracted using the mass-spring simplified model of contained liquid. A parametric study was performed by employing the non-linear solution of the governing equations and the effectiveness of the proposed system for all AST aspect ratios is discussed. The numerical results show that the overturning moment of the tanks equipped with the proposed isolation system decreased significantly with respect to the corresponding fully anchored tanks. The results of the parametric study on the tank aspect ratio and liquid height indicate that the proposed system is more efficient for slender tanks than for broad tanks.