| Project/Area Number |
06452293
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Architectural environment/equipment
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| Research Institution | Kobe University |
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Principal Investigator |
MORIMOTO Masayuki Professor, Faculty of Engineering, Kobe Univ., 工学部, 教授 (10110800)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAGAMI Kimihiro Research Associate, Faculty of Engineering, Kobe Univ., 工学部, 助手 (90231331)
KITAMURA Yasutoshi Professor, Faculty of Engineering, Kobe Univ., 工学部, 教授 (20031099)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | elevated structure noise / elevated motor way / sound radiation / noise control / vibration / model analysis / boundary element analysis / 高架構造物 / 桁 |
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| Research Abstract |
The problems with the elevated structure noise, which is the noise in audio-frequency range radiated from the structural elements of the elevated motorway, recently arises around the elevated motorways. To investigate the mechanism of the generation of, and to establish the countermeasure to the elevated structure noise, the following considerations were carried out :
1. Model analysis of the acoustic radiation of steel I-beams : The sound radiation characteristics of web plate of steel I-beams were analyzed using a simplified model. The beam was modelled a baffled strip of elastic plate of infinite length in the model analysis. The features of the calculated results were discussed in comparison with those of those of the actual elevated structure noise in order to shed some light on the main cause of the noise.
2. Boundary element analysis of the vibration of steel I-beams : To make a further investigation on the main cause of the noise, vibration of a steel I-beam was analyzed by bound
… More
ary element method (BEM). The relationship between the elevated structure noise and the structure of the beam was discussed in detail from the above BEM results.
As the results from the model analysis, the radiated sound from an elastic plate strip of infinite length was found to have very similar features to the elevated structure noise. This can be interpreted to imply that steel I-beams can possibly be the main cause of the elevated structure noise. The results of the BEM analysis show that the transverse vibration, which may be the most responsible to sound radiation, is dominant in the web plate around 500Hz, and it is still dominant when the web is excited by a nearly in-plane force. These results suggest that the web plate of steel I-beams is strongly relevant to the elevated structure noise. From the above results, it can be concluded that the main cause of the elevated structure noise is the web plate of steel I-beams. Though there is still some problems to be solved, which include the actual excitation condition of the beam, for example, the above results can help with basic ideas for countermeasures to the elevated structure noise problems. Less
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