Simple design procedure for liquid-filled steel conical tanks

Conical steel vessels, having an upper cylindrical section and supported by a reinforced concrete shaft, are becoming widely used for water containmen t in elevated tanks. However, the current codes of practice for water struc tures in North America do not include any rational method for designing suc h vessels. In this study, a simple and rational design procedure that consi ders instability, yielding, large deformations, geometric imperfections, an d residual stresses is developed for these hydrostatically loaded steel ves sels. The procedure is based on a verified finite-element model and employs a multiple-regression analysis to develop formulas that relate the maximum stresses resulting from the hydrostatic pressure to geometric and thicknes s parameters. The approach uses these formulas to permit the design of vari able thickness liquid-filled conical tanks that are subjected to both hydro static and snow load. Verification of the design procedure is carried out t o prove that the procedure is accurate, economical, and conservative.