Research On Equivalent Model Of Sound Radiation Prediction For Box Girder Bridge Of High-speed Railway

With the large-scale construction of high-speed railway network,high-speed railway makes people’s travel more efficient and convenient,while the noise pollution it produces has a great impact on the noise sensitive areas along the residential environment.There is a large proportion of Bridges in high-speed railway line,and the structural noise produced by the train when it passes through the bridge has caused a great harm to the lives of residents along the line.Therefore,it is very important to carry out accurate and rapid prediction of sound radiation and noise reduction measures of high-speed railway box girder bridge.Based on the interaction theory of multi-body system and acoustic boundary element method,the vehicle-rail-bridge coupling dynamics model and acoustic boundary element model of box girder bridge are established in this paper.The vibration characteristics and acoustic radiation characteristics of box girder bridge are analyzed systematically.Taking the roof structure of equivalent box girder bridge with the largest contribution of sound radiation as the research object,a single roof with reasonable constraints is adopted.The boundary element method is used to calculate the equivalent roof radiation power,and the proportional coefficient between equivalent roof and box girder bridge sound power in peak frequency band is solved,and the curve fitting of the proportional coefficient is carried out to obtain the equivalent model of sound radiation prediction.On this basis,based on the equivalent roof with higher computational efficiency,the paper carries out the research on the noise reduction measures of bridge roof thickening,roof reinforcement and high elastic fastener.The main results are as follows:(1)The vibration characteristics of box girder bridge in high-speed railway mainly include the whole vibration and the local vibration of roof.The sound power of box girder bridge increases first and then decreases.The sound power in 0-50 Hz frequency band is obviously stronger than other frequency bands.The roof is the most important contribution plate of sound radiation of box girder bridge,so the equivalent model of sound radiation prediction of box girder bridge is established with the roof as the research object.(2)A single roof constrained by spring elements with more reasonable stiffness and spacing is selected as the equivalent roof.The proportional coefficients of equivalent roof and box girder bridge sound power in peak frequency band were solved,and the curve fitting of the proportional coefficients was carried out to obtain the equivalent model of sound radiation prediction.The radiation noise of the whole bridge in the peak frequency band can be predicted more accurately by multiplying the equivalent model with the equivalent roof sound power.For the radiation noise of other frequency bands,the equivalent roof noise can be directly replaced.Compared with the box girder bridge,the number of equivalent roof units and nodes is greatly reduced,and the prediction efficiency of acoustic radiation is greatly improved.(3)Using equivalent model and equivalent roof to study the noise reduction measures of box girder bridge will greatly improve the efficiency of calculation and the calculation results are more accurate.Equivalent roof local thickening,overall thickening,longitudinal reinforcement can significantly reduce the vibration response of the bridge,has a good vibration reduction effect;In terms of noise reduction effect,local thickening,overall thickening and longitudinal reinforcement of the equivalent roof can significantly reduce the radiated noise of the bridge,and the overall thickening has the best vibration and noise reduction effect.The stiffness of fastener has a great influence on the vibration characteristics and acoustic radiation characteristics of bridge.With the stiffness of fastener decreasing,the vibration and acoustic radiation of box girder bridge will also decrease to varying degrees.