Formulae for Evaluating Buckling Strength of FBR Main Vessels under Earthquake Loading

Although plastic shear-bending buckling of the cylindrical part of Fast Breeder Reactor (FBR) main vessels under horizontal earthquake loading is one of the most critical problems in structural design, the evaluation method of buckling strength is not specified in related standards in Japan. Central Research Institute of Electric Power Industry (CRIEPI), commissioned by the Ministry of International Trade and Industry of the Japanese government, is carrying out verification tests of fast breeder technologies (from FY 1987 through 1993). The Demonstration Test and Research Program of Buckling of FBR is part of the commissioned research program, and the first half was accomplished after establishing a seismic buckling design guideline (a tentative draft) in FY 1989. The purpose of this paper is to describe the results of static buckling tests and numerical analyses, and to present formulae for determining the buckling strength of FBR main vessels. Shear buckling and bending buckling are evaluated under the assumption that both buckling modes slightly interact with each other. Regarding shear buckling, shape imperfection within the plate thickness is considered in the formulae originally, and a correction factor for larger imperfections is provided