2005 Fiscal Year Final Research Report Summary
Study on Development of Seismic Design Method for Steel Structures Considering Ductile Facture
| Project/Area Number |
16560410
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
GE Hanbin Nagoya Univ., Dept.of Civil Eng., Assoc.Professor, 大学院・工学研究科, 助教授 (90262873)
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| Co-Investigator(Kenkyū-buntansha) |
USAMI Tsutomu Nagoya Univ., Dept.of Civil Eng., Professor, 大学院・工学研究科, 教授 (50021796)
KASAI Akira Nagoya Univ., Dept.of Civil Eng., Lecturer, 大学院・工学研究科, 講師 (20303670)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Ductile Crack / Steel Bridge / Strain Concentration / Structural Detail Factor / Ultimate Strain / Local Strain / Loading History / Seismic Design Method |
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| Research Abstract |
The present study was aimed at developing a seismic evaluation procedure for steel structures considering the evaluation of ductile crack initiation, which is the first step of brittle fracture.
Firstly, a prediction criterion for structural steels against ductile crack initiation was proposed with the help of FEM necking process simulation on a round bar. In the analysis, void evolution was introduced as a technique for considering the section loss in the large strain range. The failure criterion of judging ductile crack initiation was decided using the void volume fraction based on the previous experimental results. Furthermore, the correlation of a local plastic strain and a global strain was shown, and the ultimate strains against the ductile crack initiation were proposed.
Secondarily, the quasi-static tests of steel columns were carried out to investigate the crack initiation mechanism and to examine the accuracy of ductile crack initiation strain proposed in a previous study.
Moreover, by performing elaborate analysis using shell elements, and fiber analysis using beam elements it's found that there exists a difference in the strain distribution at the point of crack initiation. As a result, a factor is proposed to account for the effect of structural details in the fiber analysis. It has been shown that ultimate state predicted by the proposed method agrees well experimental result.
It should be noted that this research is a basic research on the development of a unified seismic design method that can be used to check failures by either local buckling or brittle fracture.
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