2005 Fiscal Year Final Research Report Summary
Investigation of spatially varying ground motions and soil-structure interaction effect on bridge girder pounding
| Project/Area Number |
15560404
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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 | Okayama University |
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Principal Investigator |
CHOUW Nawawi Okayama University, Graduate School of Environmental Science, Researcher, 環境理工学部, 非常勤研究員 (70274016)
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| Co-Investigator(Kenkyū-buntansha) |
HIROSE Sohichi Tokyo Institute of Technology, Graduate School of Information Science and Engineering, Professor, 大学院・情報理工学研究科, 教授 (00156712)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Near-source earthquake / Response of soil-foundation-structure system / Non-linear response of soil-structure system / Pounding of bridge girders / Spatial variation of ground motions / Soil-structure interaction / Prevention of bridge girder unseating / Gap between girders |
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| Research Abstract |
The subject of the investigation is the simultaneous influence of spatial variation of ground motions and soil-structure interaction on the relative response of bridge structures. The duration of this research project is three years, and the fiscal year 2005 is the last year.
In the following the results of the investigation are summarized :
If the soil is soft and the neighbouring structures do not have the same slenderness, even though they have the same fixed-base fundamental frequency and experience the same ground excitation, pounding can take place, because with different slenderness both adjacent structures can vibrate out-of-phase.
In the case of frequency ratio larger than 0.6 the simultaneous effect of non-uniform ground motions and soil-structure interaction can significantly amplify the girder damage potential due to larger contact forces. Consequently, damage due to multiple subsequent poundings is possible.
In the frequency ratio range around 1.0 and also in the higher freque
… More
ncy ratio range above 1.6 non-uniform ground motions have stronger influence than soil-structure interaction. If the adjacent structures have different slenderness, however, soil-structure interaction can have stronger effect than non-uniform ground motions even at the frequency ratio of 1.0.
Although the Japanese design specification is currently the most advanced and strictest regulation and implicitly includes the effect of spatial variation of ground motions, the required seating length may still not be adequate, especially when the neighbouring bridge structure is flexible and when both structures experience different SSI.
Different soil-structure interaction can also occur, even though both adjacent structures have the same slenderness, the same fundamental frequency and experience the same ground excitation, if the supporting soil is spatially not uniform. This unequal soil-structure interaction can significantly affect the relative structural response. It should be incorporated together with the influence of spatially non-uniform ground excitation in future design regulations. Less
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[Journal Article] Reduction of the pounding effect between bridge girders induced by spatially varying ground motions2004
Author(s)
Su, H., Hao, H., Chouw, N.
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Journal Title
8th International Symposium on Structural Engineering for Young Experts, Xi'An, China, August 20-23, 2004,ISBN 7-03-013765-5/TU
Pages: 296-302
Description
「研究成果報告書概要(和文)」より
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