2021 Fiscal Year Final Research Report
Clarification of Sequential Seismic Loads Mechanism Acting on a Long-Period Bridge and its Visualization
| Project/Area Number |
19K21983
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 22:Civil engineering and related fields
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| Research Institution | University of Tsukuba |
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Principal Investigator |
Shoji Gaku 筑波大学, システム情報系, 教授 (60282836)
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| Co-Investigator(Kenkyū-buntansha) |
市村 強 東京大学, 地震研究所, 教授 (20333833)
牧 剛史 埼玉大学, 理工学研究科, 教授 (60292645)
長山 智則 東京大学, 大学院工学系研究科(工学部), 教授 (80451798)
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| Project Period (FY) |
2019-06-28 – 2022-03-31
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| Keywords | 長周期型橋梁 / 強震動 / 地表断層変位 / 連鎖地震荷重 / 作用メカニズム / 地震応答の視覚化 |
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| Outline of Final Research Achievements |
A three-dimensional finite element model was constructed for the long-period bridge-ground system of the Ohkirihata Bridge and Kuwazuru Bridge damaged by the Kumamoto earthquake, and the mechanism of the sequential seismic loads acting on the system was revealed, focusing on strong ground motions and deformation of supporting ground such as surface fault displacement. For the Ohkirihata Bridge, the strong ground motions seem to dominantly cause the horizontal displacement of slabs and girders, the shear failures of laminated rubber bearings, and the inelastic response and inclination of pier P4. In addition, the surface fault displacements seem to increase the above nonlinear responses from pier P2 to pier P4. Regarding the Kuwazuru Bridge, the sequential damage process was clarified in which the girder end was lifted due to the loss of the support function of the bearings at the abutment, and the cable stress was released and the girder end collided with the wall at the abutment.
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| Free Research Field |
防災・減災工学
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| Academic Significance and Societal Importance of the Research Achievements |
連鎖地震荷重として強震動及び地表断層変位等の支持地盤の変状に焦点を当てて，熊本地震で被災した大切畑大橋と桑鶴大橋に対する未解明であった連鎖地震荷重の作用メカニズムを推定できた点に大きな学術的意義が認められる．長周期型橋梁を構成する構造要素や地盤の連成する複雑な地震応答を時刻歴波形だけでなく3D CADを活用して3次元的に視覚化できた点においても有用な知見を示し得ており大きな社会的意義が認められる．
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