1998 Fiscal Year Final Research Report Summary
A study on development and application of high performance steel for bridge structures
| Project/Area Number |
08305014
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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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, Department of Engineering, Professor (20016645)
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| Co-Investigator(Kenkyū-buntansha) |
MIKAMI Ichizou Kansai University, Department of Engineering, Professor (80067636)
MASUDA Nobutoshi Musashi Institute of Technology, Department of Engineering, Professor (00016700)
FUJII Katashi Hiroshima University, Department of Engineering, Professor (60127701)
MORI Takeshi Hosei University, Department of Engineering, Professor (10157860)
ICHIKAWA Atsushi Tokyo Institute of Technology, Department of Civil Engineering, Professor
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| Project Period (FY) |
1996 – 1998
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| Keywords | High performance steel / Fracture toughness / Brittle fracture / Fatigue behavior / Low cvcle fatigue / Large input heat welding / High strength steel |
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| Research Abstract |
In this research project, the objective is to develop and apply high performance steel for bridge structures. The followings were studied.
1) Deterioration of fracture toughness due to large plastic strain: Concerning the cold-worked bending process or huge earthquakes, the deterioration of fracture toughness due to large plastic strain was studied. In addition, the differences of effect between tensile plastic strain and compressive plastic strains were discussed with some kinds of steels by observation of brittle fractured surface and mechanical testing.
2) Possibility of large input heat welding: Because of some negative effects, such as cracks or deterioration of properties and so on, generally, it has been prohibited to, apply the large input heat welding. In this research project, concerning the high performance steels, the applicability of large input heat welding was tested with carrying out the CTOD testing of large scale welded girder specimens.
3) Fatigue Performance of High Strength Steel: For rationalization of steel bridges, fatigue performance of high strength steels was discussed with joint and large-scale girder specimens. In this study 900 MPa class steel, which has never used for actual bridges, was dealt with. In addition, improvement methods of fatigue strength were also studied.
4) Low Cyclic Fatigue Behavior under Earthquake: Concerning the low cycle fatigue failure of steel pier under earthquake, low cyclic fatigue testing was carried out, and damage accumulation mechanism was studied
5) Brittle Fracture of Beam-Column Joint: In order to improve the toughness and ductility of steel beam-column joint, cyclic loading testing was carried out and some retrofitting and improving techniques were also tested. In that testing, brittle fracture which initiated from that welded corner could be simulated experimentally. As a result, decreasing the strain concentration at the corner with corner rib was the most effective for prevention of brittle fracture.
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