2020 Fiscal Year Final Research Report
Axial Collapse Mechanism and Its Prevention Method for Reinforced Concrete Beam-Column Joint Failing in Joint Hinging
| Project/Area Number |
18K04435
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 23010:Building structures and materials-related
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 建築構造・材料 / 鉄筋コンクリート構造 / 柱梁接合部 / 降伏破壊 / 軸崩壊 |
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| Outline of Final Research Achievements |
Many reinforced concrete (R/C) buildings consisting of beam-column frames have collapsed during earthquakes because the beam-column joint region which failed in joint-hinging was not able to sustain the column axial load. Such a collapse mechanism for R/C corner column-beam joints was investigated through laboratory tests using beam-column subassemblages subjected to bi-directional lateral loads and varying column axial load. Primary findings drawn from the study are as follow.
Axial collapse in a corner column-beam joint was accelerated by column axial load varying from tension to compression and bi-lateral cyclic reversed loads. Crash of concrete and local buckling of column longitudinal bars within the joint, placed along column faces without framing beams, caused an abrupt inclination of the upper column to the lower column, inducing a loss of ability for sustaining vertical load.
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| Free Research Field |
建築構造学
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| Academic Significance and Societal Importance of the Research Achievements |
地震動を受けた鉄筋コンクリート（RC）建物の柱梁接合部が曲げ降伏破壊したあと、三方向地震動によって軸崩壊に至る力学機構を三つのモードに分類してその特徴を明らかにした。本研究で実施したRC柱梁部分骨組の実験に基づき、柱梁接合部内で柱主筋が座屈しコンクリートが圧壊することで、上柱と下柱とが柱梁接合部を中心に折れ曲がって柱軸力を保持できなくなり、軸崩壊することを指摘した。
この成果は、RC柱梁接合部の軸崩壊を防止するための新しい耐震設計法の提案に活用できる。これは、新規に設計する鉄筋コンクリート建物の耐震性能の向上および建物の長寿命化に貢献するため、社会的な意義は大きい。
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