2012 Fiscal Year Final Research Report
Estimation of Residual Life of Fatigue Cracked Steel Bridge Members
| Project/Area Number |
22360177
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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 |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
HANJI Takeshi 名古屋大学, 大学院・工学研究科, 准教授 (80452209)
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| Project Period (FY) |
2010 – 2012
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| Keywords | 鋼橋 / 疲労 / 溶接継手 / 面外曲げ / 応力拡大係数 |
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| Research Abstract |
Stress intensity factor (SIF), an essential parameter to identify the crack propagation behavior, under out-of-plane bending condition was obtained analytically, and verified with fatigue tests. The SIF at crack front of through-thickness crack varies in plate thickness direction under out-of-plane bending, and the SIF distribution along crack front is influenced by the crack length and the crack thickness. Based on the results, a simple equation for estimating the SIF of through-thickness fatigue crack subjected to out-of-plane bending was proposed.
As an actual fatigue damage experience caused by out-of-plane bending, propagation behavior of through-thickness fatigue crack detected in orthotropic steel deck was investigated. Fatigue crack originated by out-of-plane bending sometimes suddenly changes its propagation direction into trough rib. By using FEA, the SIF of the through-thickness crack was estimated, and the propagation direction of the fatigue crack was predicted by the maximum energy release rate criterion. Based on the analysis results, crack growth mechanism and reason of the directional change were explained.
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