水平及び鉛直荷重を受ける円筒容器の座屈強度に及ぼす初期不整形状の影響に関する研究

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

岡藤 孝史*; 三浦 一浩*; 佐郷 ひろみ*; 村上 久友*; 安藤 勝訓 ; 宮崎 真之

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

高速炉の容器を大型化することに伴う直径と板厚の比の増加や免震設計への適用に対応するため、軸圧縮,曲げおよびせん断荷重下で弾塑性座屈を評価できる座屈評価方法を開発している。本研究では、弾塑性解析により容器全体にわたる長波長の初期不整形状の座屈強度への影響を評価し、新たに提案する座屈評価式の適用性評価及び初期不整量を評価する際のゲージ長の検討を実施した。また、溶接による局所変形・残留応力についても、同様に解析により座屈強度への影響を評価した。

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.