| Project/Area Number |
19K04577
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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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| Review Section |
Basic Section 22020:Structure engineering and earthquake engineering-related
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2021: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2019: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 溶接 / 残留応力 / 疲労 / 局所加熱 / 鋼床版 |
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| Outline of Research at the Start |
疲労き裂が多発する鋼床版端部の垂直補剛材と縦リブが近接する領域を対象に，溶接線が複雑に配置される狭隘構造における残留応力分布の特徴を，モデル供試体を用いた実験および熱弾塑性解析により明らかにする．さらに，対象とする構造の耐疲労性を向上させるため，高周波誘導加熱装置による比較的低温の局所加熱を施し，溶接部の引張残留応力を低減させる技術の適用を試みる．そして，残留応力の低減効果を定量的に明らかにするとともに，疲労試験を行い，残留応力の低減による耐疲労性の向上効果を明らかにする．
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| Outline of Final Research Achievements |
The purpose of this study is to clarify the characteristics of welding residual stress and to improve fatigue resistance of steel bridge decks in which fatigue cracks are prone to occur, especially in the region between vertical stiffeners and longitudinal ribs at the edge of narrow slabs. Thermal elastic-plastic analysis was performed on a small specimen modeling the target structure to confirm that local heating reduces welding residual stresses. Fatigue tests were performed on the specimens as welded and with local heating. As a result, the fatigue life of the locally heated specimen tended to be significantly longer than that of the as-welded specimen. It was found that the effect of fatigue life improvement was strongly influenced by the condition of cyclic external loads.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究成果により，局所加熱による溶接残留応力の低減が道路橋鋼床版の端部垂直補剛材とデッキプレートのまわし溶接部に適用可能であることが明確になった．また，局所加熱による残留応力の低減が疲労寿命の向上効果にどのように寄与するのかを明らかにしたことは学術的に大きな意義を有する．また，既存の疲労寿命向上技術と，本研究で注目した局所加熱の疲労寿命向上効果を比較することで，その位置づけを明確にしたことは，実用化に対する具体的な知見を示したものであり，その社会的意義は大きいと言える．
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