1989 Fiscal Year Final Research Report Summary
Integrity and Strength of Offshore Structure Suffered from Deterioration during Service Period
| Project/Area Number |
62302035
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
船舶構造・建造
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| Research Institution | Osaka University |
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Principal Investigator |
UEDA Yukio Osaka Univ., Welding Research Institute, Professor, 溶接工学研究所, 教授 (30029037)
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| Co-Investigator(Kenkyū-buntansha) |
OKADA Hiroo Univ. of Osaka Pref., Faculty of Engin., Professor, 工学部, 教授 (90081398)
YAO Tetsuya Hiroshima Univ., Faculty of Engineering, Professor, 工学部, 教授 (20029284)
IWATA Mitsumasa Hiroshima Univ., Faculty of Engineering, Professor, 工学部, 教授 (80034346)
MURAKAWA Hidekazu Osaka Univ., Welding Research Institute, Assoc. Prof., 溶接工学研究所, 助教授 (60166270)
TOMITA Yasumitsu Osaka Univ., Faculty of Engineering, Professor, 工学部, 教授 (30029251)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Offshore Structure / Joint Strength / Deterioration / Corrosion / Collision Strength / Crack Damage / Fatigue Strength / Reliability analysis |
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| Research Abstract |
1. As external loads acting to offshore structures, waves in actual sea was analyzed statistically and the characteristics of irregular waves was discussed.
2. The corrosion rate of offshore structure in very sever circumstance is found to be approximately 2 to 10 times as high as 0.1mm/year of usual cases. In order to find optimum location of cathod, a method of theoretical analysis was developed. In parallel with this, a method of reliability analysis of deteriorated cylinder by fatigue crack was developed for plastic collapse under compression. The effect of the magnitude and distribution of corrosion in cylinders was theoretically analyzed on compressive collapse loads.
3. The hydrodynamic effect on structural behavior of offshore structure collided by supply boats was investigated. The dynamic behavior of an entire offshore structure is classified so that the damage of collided member can be estimated efficiently.
4. Effects of crack-damage on the rigidity and strength of cylindrical members were investigated both theoretically and experimentally. Relationship between axial buckling and propagation of cracking of cylindrical shell was experimentally clarified.
5. Numerical analysis by FEM was carried out on the rigidity and strength of the joint between chord and several braces, to which the axial forces and bending moments are transmitted three-dimensionally from the braces.
6. Based on the characteristics of existing fatigue testing methods, several predicting methods of fatigue strength of joint including the effect of corrosion was examined.
7. The system of reliability analysis of framed structures was extended to include gradual deterioration and applied to offshore structures of jacket-type and of guide-tower type.
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