| Project/Area Number |
61460177
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | NAGOYA UNIVERSITY |
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Principal Investigator |
MATSUI TETSUYA NAGOYA UNIVERSITY, SCHOOL OF ENGINEERING, 工学部, 助教授 (70023083)
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| Co-Investigator(Kenkyū-buntansha) |
KATO KENJI TOYOTA COLLEGE OF TECHNOLOGY, 講師 (80043206)
OHMORI HIROSHI NAGOYA UNIVERSITY, SCHOOL OF ENGINEERING, 工学部, 助手 (90092387)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1987: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1986: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Keywords | Floating offshore structures / Irregular waves / Moored vessel / Wave drift force / 長周期運動 |
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| Research Abstract |
A series of theoretical and experimental investigations have been conducted to predict the slow drift motion and mooring line forces for floating structures in irregular sea waves. The resluts obtained from this project are summarized as follows:
(1) An exact method for simulating the slow drift motion and mooring line forces for floating offshore structures has been proposed within the framework of the second order potential flow theory. The method has been applied to understand the slow drift behaviour of such structures as an articulated column and a moored semi-submersible. It was confirmed that the simulated time histories of the slow drift motion of the semi-submersible are in fairly good agreement with the measured ones in model tests, if the viscous damping term is evaluated appropriately, say by means of the Morison formula.
(2) A specific instrument for the random forced oscillation test has been manufactured to measure the hydrodynamic forces on an articulated column model in the low frequency motion. The effects of the high frequency motion of the column and the incoming waves on the hydrodynamic forces have been investigated in dateil. The conclusions arising from the test are listed in the following:
a) The hydrodynamic damping of the articulated column in the low frequency motion is mainly due to viscous effects.
b) Such damping forces are strongly influenced by the presence of the high frequency motion of the column as well as the incoming waves. Due to small number of the measured data their significant scatter observed. it is difficult at the present stage to predict quantitatively the hydrodynamic forces on the column in the low frequency motion. This will be a matter for future research.
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