Buckling of Externally Pressurized Prolate Ellipsoidal Domes

Details are given of a numerical and experimental study into buckling of steel ellipsoidal domes loaded by static external pressure. A range of geometries and thicknesses of domes is examined, as is the influence of different boundary conditions. Shells are examined on the basis of having the same mass. The main focus of the study is on prolate domes, i.e., those taller than a hemisphere of the same base radius. Numerical predictions are confirmed by pressurizing six laboratory scale prolate domes to destruction. Details are given of the manufacture and test procedure for the domes. The adverse effects of variations in shape and wall thickness are discussed, and finite element predictions are made for geometrically imperfect domes. Correlation between the two sets of results is good. Numerically and experimentally obtained results are related to the current design codes: ASME Boiler and Pressure Vessel Code, Sec. 8, Division 2 (described hereon as ASME VIII), PD5500, and ECCS recommendations (ASME B&PV Code, 2004 ed., Sec. 8, Division 2, New York, NY; BSI 2003 “Published Document PD5500: Specification for Unfired Pressure Vessels,” BSI London; European Convention for Constructional Steelwork Recommendations, 1988 “Buckling of Stell Shells-European Recommendations,” ECCS-TWG 8.4, 4th ed., Brussels), which at present make no provision for prolate domes. Suggestions are made for the possible inclusion of such domes into the standards.