A Study on Structural Standardization of Connections of Floating Offshore Structure

Research Project

Project/Area Number	60850081
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	船舶構造・建造
Research Institution	University of Tokyo
Principal Investigator	YOSHIDA Koichiro Faculty of Engineering, University of Tokyo, 工学部, 教授 (90010694)
Co-Investigator(Kenkyū-buntansha)	小野木宏日本鋼管(株), 重工研究所, 構造研究室長 KOH Yunbo Faculty of Engineering, Nagasaki Institute of Applied Science, 工学部, 助教授 (70103398) 福岡哲二 (株)三井造船昭島研究所, 主任研究員 TAMEHRO Masaki Faculty of Engineering, Hiroshima University, 工学部, 教授 (70155274) ONOGI Hiroshi Heavy Engineering Institute, Nippon Kokan FUKUOKA Tetsuji Mitsui Zosen Akishima Institute 栖原寿郎九州大学, 応用力学研究所, 教授 (60038528)
Project Period (FY)	1985 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥27,800,000 (Direct Cost: ¥27,800,000) Fiscal Year 1987: ¥5,000,000 (Direct Cost: ¥5,000,000) Fiscal Year 1986: ¥11,000,000 (Direct Cost: ¥11,000,000) Fiscal Year 1985: ¥11,800,000 (Direct Cost: ¥11,800,000)
Keywords	Semisubmersible / Structure of Connection / Internal Reinforcement / Transmission of load / Bukcling-Collapse Strength / Fatigue Strength / Model Test / 有限要素法 / 浮遊式海洋構造物 / 標準化 / 応用分布 / 座屈崩壊 / 統計分析 / 応力分布
Research Abstract	Based on results of survey of structural reinforcements at connections of actual semisub- mersibles, two cases were inverstigated in this study; a case wher a brace is directly welded to outer surface of column and a case where a brace penetrates a column shell wall. On the other hand, based on results of analyses of actual semisubmersibles subjected to design waves, 12 kinds of foundamental load patterns were proposed to express loading conditions of connections by linear superposition of these foundamental load patterns. It was also confirmed that exial force applied to brace is dominant in structural strength of connection. Therefore, axial forces were mainly applied to braces in this study. Tests using several Kinds of small scale acrylic models and calculations by the FEM were carried out in order to discuss transmission mechanism of load between internal reinforcement members of connection. It was clearified by thid study that such a case where a brace penetrates column shell wall and it is supported by a hrizontal diaghragm is the most effective from stress flow and weight minimizaing view points. Buckling-collapse strength was studied by samll scale steel model tests and FEM calculations on specimens with differenct internal reinforcement members. It was concluded by these investi- gations that connections with brace penetration and internal supporting memberf of horizontal diaghragm or ring girder have relatively high resisntance to buckling-collapse. In the latter case, selection of face plate and appropriate allocation of tripping brackets for web platge of ring girder are important. By using both small and large scale steel models, fatigue tests were carried out. It was clarified that the reinforcement method mentioned above showe high resistance to fatigue. Moreover, significance of crack initiation life, through-thickness life and failure life was discussed as a general aspect of the case of specimens with complicated reinforcement members.