Sound Radiation Characteristics of Viaducts in High-Speed Railway

Noise radiated from the elevated bridge structure in high-speed railway is a great concern. In order to analyze the noise radiation characteristics of box bridge structure, two couples of steady-state load are applied at the center of box bridge with double lines, and then using the modal of box bridge structure and the acoustic transfer vector the linear relationship between bridge surface vibration velocity and sound pressure is established in frequency domain by the direct boundary element method. Then the modal displacement is transformed into a vibration velocity vector for the calculation of the noise radiation characteristics of arbitrary points in the acoustic field with the modal acoustic transfer vector. The study results show that modal acoustic transfer vector method can adequately be combined with vibration characteristics of the box bridge itself, so it can more accurately reflect the influence of the box bridge's own structural characteristics on structure noise radiation. In addition, it can reduce the computation time. With the distance increasing horizontally from the bridge center, the box bridge noise radiation will decrease in some positions, but it will increase in other places. The sound pressure distribution of vertical direction away from the bridge surface at the distance 30m horizontally fluctuates obviously with frequency. With the distance increasing vertically above the bridge, sound pressure will decrease gradually. Overall, the sound pressure above the bridge is lower than under the bridge.