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| Vibration and Noise Analysis of Single Line U Beam in Urban Rail Transit |
| LUO Wen -jun，CHENG Long |
| (Engineering Research Center of Railway Environment VilDration and Noise，Ministry of Education，East China Jiaotong University，Nanchang，Jiangxi 330013, China) |
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Abstract Abstract ： Research purposes ： The finite element prediction model of beam - plate vibration including rail，ballastless track and bridge structure is established，and the vibration and its structural noise in the frequency range of 20 ?200 Hz under tlie direction of vertical wheel - rail force are analyzed. The vibration characteristics of the U - beam in the frequency domain， the structural noise characteristics of the near and far - field of the U - beam and the acoustic contribution of each plate are discussed. Aiming at the problem of low frequency noise of bridge structure，the vibration and noise of U - beam are analyzed，and the optimization of section is proposed. Research conclusions： ( 1 ) The amplitude of the vibration amplitude of the U - beam is about 31. 5 ~ 63 Hz， the amplitude of the wing is the largest，followed by the bottom plate and the web. (2)The vibration power level loss from rail to Ubeam is about 16. 9 dB to 20 dB，and the vibration power level of Ubeam is basically the same as that of sound pressure contribution that of bottom plate > web > wing plate. ( 3 ) The peak value of the sound pressure level in the near field is 50 Hz，the sound pressure level of the bottom plate is the largest，followed by the web and the wing. ( 4) The far - field noise is mainly affected by the bottom plate that the role of the pressure contribution is about 81 %，should be the main noise reduction object, while the vilDration peak of tlie wing is large, but tlie impact on the sound field is very small, almost negligible. (5) The research results can provide a reference for the bridge vibration and noise reduction measures of urban rail transit.
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Received: 20 February 2017
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2017, Vol. 34 
