2023 Fiscal Year Research-status Report
地震荷重下の高張力鋼溶接継手のデジタルツインベースの低サイクル疲労評価
| Project/Area Number |
23KF0050
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| Research Institution | Osaka University |
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Principal Investigator |
堤 成一郎 大阪大学, 大学院工学研究科, 准教授 (70344702)
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| Co-Investigator(Kenkyū-buntansha) |
LUO PENGJUN 大阪大学, 大学院工学研究科, 外国人特別研究員
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| Project Period (FY) |
2023-04-25 – 2025-03-31
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| Keywords | fatigue / crack / weld / seismic safety / plasticity |
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| Outline of Annual Research Achievements |
Based on the experimental and numerical studies was conducted in this research, It is concluded that the influences of weld toe shape and hardness distribution on the low-cycle fatigue behavior of steel welded joints was identified clearly. Also, due to its outstanding accuracy and robustness in evaluating both the fatigue crack location and fatigue life for the investigated butt-welded joints, the proposed combination of SCF formula with SMF formula is the most recommended method for the one-side full penetration butt-welded joints. These results can provide deep insights into the improvement of low-cycle fatigue life of steel welded joints, which are crucial to ensure the seismic safety of building structures and to mitigate the disastrous effects under long-period ground motions. These results can also help us establish a low-cycle fatigue life evaluation method in capable of considering multiple critical parameters, which will provide a useful tool for evaluating the safety and reliability of welded joints in building structures.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The fatigue behavior of butt-welded joints were investigated. Misalignments and weld geometries (including weld toe radius, flank angle, weld reinforcement height, and width) were measured using a 3D optical scanning system and subsequently used for fatigue evaluation. The test results indicate a noticeable decrease in nominal stress fatigue strength as the assembled axial eccentricities increase. Several stress magnification factor (SMF) and stress concentration factor (SCF) formulae available in the literature are employed to characterize the combined effects of misalignment and weld geometries. The investigation results indicate that misalignments and weld geometries both play critical roles in the fatigue behavior of butt-welded joints.
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| Strategy for Future Research Activity |
Due to its outstanding accuracy and robustness in evaluating both the fatigue crack location and fatigue life for the investigated butt-welded joints, the proposed combination of SCF formula with SMF formula is the most recommended method for the one-side full penetration butt-welded joints. However, the general applicability of the proposed method should be further confirmed through additional test results, as the current study is limited by the number of specimens.
So, the further experimental research is planed under various conditions including geometry and loading effects.
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