2018 Fiscal Year Final Research Report

Ultimate longitudinal bending strength of ship hull girder considering multi-axial stress and repeated loading effects

Research Project

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Project/Area Number	15H02328
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Research Field	Naval and maritime engineering
Research Institution	Osaka University
Principal Investigator	Fujikubo Masahiko 大阪大学, 工学研究科, 教授 (30156848)
Co-Investigator(Kenkyū-buntansha)	柳原大輔九州大学, 工学研究院, 准教授 (10294539) 田中智行広島大学, 工学研究科, 准教授 (20452609) 山本元道広島大学, 工学研究科, 准教授 (30274111) 田中義照国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (40373419) 飯島一博大阪大学, 工学研究科, 教授 (50302758) 辰巳晃大阪大学, 工学研究科, 助教 (60736487) 堤成一郎大阪大学, 接合科学研究所, 准教授 (70344702)
Project Period (FY)	2015-04-01 – 2019-03-31
Keywords	船体構造 / 座屈強度 / 縦曲げ最終強度 / 繰り返し荷重 / 多軸応力 / コンテナ船
Outline of Final Research Achievements	When a double bottom of ships is subjected to bending due to lateral loads, bi-axial compression is exerted in the bottom plate and they affect the ultimate longitudinal bending strength of ship hull girder in the hogging condition. Under repeated wave loads, buckling deformation of bottom plate may be accumulated and this may further decrease the ultimate hogging strength. In this study, the ultimate hogging strength of a hull girder of container ships was analyzed by nonlinear FEM considering the effect of bottom local loads. The buckling/plastic collapse behavior of a continuous stiffened panel under repeated bi-axial thrust is examined both experimentally and numerically. The cumulative collapse behavior of a hull girder under wave loads was investigated by simplified collapse analyses and wave tank test. Based on the results, the effect of multi-axial stress states and repeated loading on the ultimate longitudinal bending strength of a ship hull girder is investigated.
Free Research Field	船舶海洋工学
Academic Significance and Societal Importance of the Research Achievements	コンテナ船の縦曲げ崩壊事故調査から、二重底の曲げ変形による二軸圧縮場が船底の座屈を加速し、さらに波浪繰り返し荷重が座屈変形を累積させて最終崩壊に至らしめた可能性が指摘された。本研究では、船底局部荷重を考慮したコンテナ船の縦曲げ崩壊挙動に関する数値解析、および二軸繰り返し圧縮荷重下の防撓パネルの崩壊試験および解析より、船体桁の縦曲げ最終強度に対する多軸応力と繰り返し載荷の影響を調べた。