| Project/Area Number |
17K06548
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | National Institute of Maritime, Port and Aviation Technology |
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Principal Investigator |
Takahashi Ichihiko 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 (30425748)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 疲労き裂 / 補修法 / ストップホール / 再発き裂 / くさび荷重 / 斜面型くさび部材 / 適応くさび部材 / 耐疲労スマートペースト / 補修 / くさび効果 / くさび / 適応型くさび部材 / 維持管理工学 / くさび部材 |
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| Outline of Final Research Achievements |
When a fatigue crack is found in structures, the most commonly used emergency measure is making a stop-hole at the crack tip, whereas cracking may reinitiate from the hole edge under certain stress conditions. In the present study, a wedge-reinforced stop-hole, which reduces the stress amplitude at the hole edge by applying a wedge load, was newly proposed and a simple repair method was examined, which is performable from one side and capable of easily and effectively halting or restraining fatigue cracks.
Specifically, a slope-type adaptive wedge member was newly designed and applied to plate specimens for fatigue tests. No reinitiation of crack was observed for the smooth hole edge and the fatigue life increased at least 20-fold by the adaptive wedge member. On the other hand, when a crack was intentionally reinitiated from a notch at the hole edge, remarkable suppression of crack growth was observed and the fatigue life increased at least 12-fold by the adaptive wedge member.
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| Academic Significance and Societal Importance of the Research Achievements |
経年構造物の損傷事例に占める疲労損傷の割合は高く、き裂補修の重要性については言を俟たないが、現場補修の自由度は限られており、応急的にストップホールを用いる場合が多い。ストップホールの補強法は種々提案されているが、施工に時間と手間がかかる、裏側にアクセスできない箇所には適用できない等の課題があり、き裂を片側からでも簡便かつ効果的に停止／抑制できる簡易補修法が待望されるところである。本研究の成果はそのような現場のニーズに応えるものであり、片側施工の容易さに加え、き裂再発防止と再発き裂の進展抑制のいずれにも有効である、実施工用に大幅なコンパクト化が可能である等々、数々のメリットを有するものである。
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