A SIMPLIFIED ANALYSIS OF EDGE SETTLEMENT OF A LARGE ABOVEGROUND LIQUID STORAGE TANK

This work is concerned with the analysis of deformation and bending moment distribution along sections of bottom plate of a large aboveground cylindrical liquid storage tank with appreciable out of plane differential edge settlement. The analysis uses approximate simple beam bending theory to model the settled section of the plate and takes into account the effects of foundation compliance, shell and hydrostatic loading and the shell-bottom plate junction stiffness. Results are presented for the effects of edge settlement maximum amplitude, plate thickness, foundation stiffness, and hydrostatic loading on the allowable edge displacement maximum amplitude. Comparison of the results of the present study with the API Standard 653 shows that the API standard 653 which does not take into account the effects foundation stiffness, plate-shell junction stiffness and plate thickness gives in general a conservative estimate of the allowable edge displacement limit and that this limit, depending on system parameters, may be relaxed by as much as 20%.