2002 Fiscal Year Final Research Report Summary
A Study on Structural Response Behavior and Strength Evaluation Systems of Submerged Floating Structures with Tension Legs in Waves
| Project/Area Number |
13450411
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
海洋工学
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
OKADA Hiroo Osaka Prefecture University Graduate School of Engineering, Prof., 大学院・工学研究科, 教授 (90081398)
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| Co-Investigator(Kenkyū-buntansha) |
KITAURA Ken-ichi Osaka Prefecture University Graduate School of Engineering, Lecturer, 大学院・工学研究科, 講師 (00081399)
KISHI Mitsuo Osaka Prefecture University Graduate School of Engineering, Assoc. Prof., 大学院・工学研究科, 助教授 (00145814)
MASAOKA Koji Osaka Prefecture University Graduate School of Engineering, Assoc. Prof., 大学院・工学研究科, 助教授 (10244659)
TSUBOGO Takashi Osaka Prefecture University Graduate School of Engineering, Research Assoc., 大学院・工学研究科, 助手 (80254431)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Submerged floating structures / Strength of tension legs / Bending (cracking) failure / Reliability analysis system / Parameter sensitivity analysis / Fatigue behavior of steel materials / Hydroelastic behavior of box girder / Collapse behavior of circular tubes |
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| Research Abstract |
(1) The first research is concerned with the elastic response behavior of marine tunnel structures with tension legs in irregular waves. First, a simplified estimation method for dynamic responses under regular oblique wave conditions is analytically presented using a simple beam on an elastic foundation. Then, a simplified estimation method is presented for the dynamic behavior under irregular wave conditions by using above analytical results and combining irregular sea wave spectra. Next, the limit state mode is presented for estimating the reliability level for cracking failure of the main body under extreme wave loads. Finally, the applicability of the methods is investigated through numerical examples carried out for a 1,000m-class marine tunnel structure with tension legs under some irregular sea state conditions. And characteristics of the short-term responses and reliability levels for the cracking failure of the main body were numerically shown. Effects of the critical moment
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for cracking failure and bending and mooring rigidities concerning with the expected value of the maximum bending moment on reliability levels are also investigated by sensitivity analysis.
(2) Next, the hydro-elastic characteristics of a submerged floating structure supported with tension legs in regular waves is investigated under some assumptions of the linear long wave theory and thin plate theory. Then, the hydro-elastic characteristics of a floating structure model with a submerged plate and tension legs in regular waves are investigated numerically. Next, in order to demonstrate the validity of theoretical results, an experimental study was carried out for a basic model in regular waves. It is found that experimental results for the frequency response amplitude were in good correspondence to theoretical results in the low frequency range. Finally, numerical studies are carried out for a 1,000m-class submerged floating structure whose was composed of double hull structure under trial design. From analytical results, characteristics of the frequency response amplitude for deflection and bending stress of the structure are investigated.
(3) In order to investigate fatigue behavior of steel materials under triple repeated stress, characteristics of behaviors on temperature and hysteresis-loop energy are experimentally investigated. The relation between fatigue life and these behaviors is considered using these experimental results.
(4) The effect of pre-strain on fatigue behavior of steel materials under perfectly repeated stress is experimentally investigated. From these results, the relation between fatigue life and behaviors on temperature and hysteresis-loop energy is considered.
(5) As a part of basic study on the collapse behavior of marine pipeline structures, effects of combined loads and partially reduced thickness due to corrosion on collapse behaviors of circular tubes under combined with bending moment and lateral pressure are numerically investigated by using a non-linear finite element method. Less
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