For different soil stiffness, foundations of large oil tanks tend to suffer settlement in non-planar configuration under load. Whilst the influences of geometric imperfections and defects on the buckling strength of cylindrical shells have been investigated extensively, few studies have investigated the influences of tank bottom settlements in the boundary conditions and the influences of tank foundation settlements have received even less attention. This paper presents an integrated numerical and experimental study on a large unanchored open-topped steel tank. The buckling behaviors of the tank are analyzed using the finite element computer package ANSYS by means of nonlinear stabilization algorithm. Various items of actual geometrical structure which involve concrete ringwall foundation of tank, unanchored bottom with slope, shell tapering from the base to the top, wind girders and supports, top angles, stiffening rings and support plates are presented thoroughly in the non-symmetrical 3D finite element model. The experiment is presented with using of strain gauges for determining of stress distribution in the shell and bottom of tank and verifying the validity of the finite element model. The effects of foundation harmonic settlement on the elephant foot buckling strength of large unanchored open-topped oil storage tanks with tapered shells under axial compression are explored by numerical modeling. Geometric nonlinearity, nonlinear boundary conditions and elastic plastic material of Ramberg-Osgood model are involved simultaneously in simulate course. The obtained solutions are displayed graphically for selected values of system parameters: harmonic settlement amplitude, harmonic number, and critical buckling stress of axially compressed oil tank. The results will provide insights into the relationship between foundation harmonic settlement and buckling strength of the large cylinders.


Elephant Foot Buckling Analysis of Large Unanchored Oil Storage Tanks With Tapered Shells Subjected to Foundation Settlement

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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