| Project/Area Number |
15360247
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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 | Ritsumeikan University |
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Principal Investigator |
IZUNO Kazuyuki Ritsumeikan University, Dept. of Civil Engineering, Professor, 理工学部, 教授 (90168328)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Hiroshi Ritsumeikan University, Dept. of Civil Engineering, Professor, 理工学部, 教授 (90066712)
KAJITA Yukihide National Defense Academy in Japan, School of Systems Engineering, Research Associate, システム工学群, 助手
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2003: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | unseating prevention system / shock absorber / seismic design of bridge / capacity design / cable / conservation of energy / deformation limit / collision between girders / 落橋防止システム / 耐震設計 / 運動方程式 / 摩擦 / 緩衝材 / 道路橋 |
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| Research Abstract |
All road bridges in Japan have been fitted with a seismic unseating prevention system to prevent bridge girders from falling during an earthquake. In the current design of Japanese highway bridges, the necessary strength of the system is prescribed to be 1.5 times the reaction force for the dead load of the bridge girder. In other words, the capacity is stipulated in terms of the dead load alone, with no consideration of the dynamic response of the bridge system.
With the emergence of the seismic unseating prevention system as an important issue in Japan, much research has been conducted in recent years. However, most studies have focused on specific factors in bridge collapse such as cable capacity, while research on the design procedure for the unseating prevention system itself remains limited. The bridge unseating prevention system has been designed based on theoretical considerations under many assumptions because it is difficult to evaluate the operation of the system during an actual earthquake. It is necessary to ensure that the system functions adequately during earthquakes.
In this study, the design of connecting devices for preventing bridge girders from becoming unseated during strong seismic motion is extended to include consideration of the velocity response of the bridge. The demand strength and cross-sectional area of the connecting cable are derived based on conservation of energy considerations. The demand capacity of the connecting cable is also defined for the worst case that the girder falls from the pier. The installation of shock absorber with optimum stiffness based on its deformation limit and the cable stiffness is found to reduce both the stress on the cable and the required cross-sectional area.
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