1994 Fiscal Year Final Research Report Summary
The Study on Improvement Method of Fatigue Strength of Steel Bridge Weld member
| Project/Area Number |
05452233
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
構造工学・地震工学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
MIKI Chitoshi Tokyo Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (20016645)
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| Co-Investigator(Kenkyū-buntansha) |
TATEISHI Kazuo Tokyo Institute of Technology Faculty of Engineering, Assistant, 工学部, 助手 (80227107)
MORI Takeshi Housei University, Faculty of Engineering, Assistant Professor,, 工学部, 助教授 (10157860)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Improvement Method of Fatigue Strength / Weld Metal / Undermatching / Post-Teating / Weld Defect / Configuration of Weld toe / Hardness / Weld Residual Stress |
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| Research Abstract |
The improvement methods of fatigue strength of weld joints were studied at the following two view points, 1.the effects of weld metal, 2.the effects of post-treating of weld toe. In this study, longitudinal weld joints and longitudinal weld rib joints were investigated. Consequdntly, the following three main results were obtained.
(1) Using longitudinal joints, the effects of undermatching of weld metals on fatigue strength of weld joints were investigated experimentally and statistically. The results showed that the undermatching makes the weld tensile residual stress at the weld joints, probability of weld defect occurrence, and probability of fatigue crack initiation from the weld defects decrease.
(2) Using longitudinal weld rib joints, the effects of weld metal and post-treating of weld toe on fatigue strength of weld joints. The results showed that changes of weld metals and post-treating affected on the configuration of weld bead (including weld toe), hardness, and weld residual stresses. And choosing appropriate weld metals and post-treating of weld toe improved the fatigue strength of weld joints.
(3) To evaluate the application of the above-mentioned two results (1) (2) to real steel bridge structure, fatigue tests with large girder specimens were performed. The large girder specimen had same wedl condition as small specimens which were used in (1) (2). The results showed that undermatching of weld metals and TIG-dressing improved the fatigue strength, and that the improvement method evaluated in this sutyd were effective on the real steel bridge structures.
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