Study on the effect of initial imperfection shape on buckling strength of cylindrical vessel under the horizontal and vertical loads

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori ; Miyazaki, Masashi

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, the effect of initial imperfection and stress of large vessels manufactured by welding multiple plates on the buckling load was evaluated via a series of analyses. In these analyses, the superimposition of global imperfection over the entire vessel due to accumulation of misalignment in buckling mode imperfection had minimal effect on the buckling load. Accordingly, the length for measuring the imperfection amplitude should correspond to the wavelength of the buckling mode. The local imperfection and residual stress by welding also exerted small effects on the buckling load.