RESEARCH ON IDENTIFICATION OF STRUCTURE-BORNE NOISE SOURCE OF HIGH-SPEED RAILWAY SIMPLY-SUPPORTED BOX GIRDER BASED ON COHERENCE ANALYSIS

Low-frequency structure-borne noise will be produced by structural vibration of bridge under train loads, which will cause noise pollution problems for residential environment. In this paper, a noise-identification method for bridge local vibration based on coherence analysis is proposed. Firstly, the noise-identification method combining spectral analysis and coherence analysis is determined. The basic theories of spectrum analysis, coherence analysis and partial coherence analysis are introduced, and an iteration solution method is used in optimal linear input model for partial coherence analysis, then the corresponding Matlab code is written. Secondly, with the measured data in the vibration & noise test for a viaduct in Cheng-Guan Railway, the mechanisms of noise radiation from structural vibration in bridge are discussed by the combined method of spectral analysis and coherence analysis, the structure-borne noise radiated from bridge is separated and identified by spatial coherence analysis and the impact area of structure-borne noise can be obtained though the analysis of multiple coherence function. Comprehensive analysis show that: coherence analysis combined with spectral analysis is an effective method to obtain the relationship between the structural vibration and structure-borne noise radiated from bridge, meanwhile the independent contributions and spectral characteristics of all structure-borne noise sources with coherent relationship can be well separated and identified, which can provide theoretical guidance for measures regarding vibration and noise reduction in bridge.