Case study: Acoustic radiation characteristics and mechanism of high-speed railway box-girder bridge

The proportion of box-girder bridges in high-speed railways in China is high. The noise caused by trains passing a box-girder bridge is more intense than the noise in other sections of the railway because it is radiated by the bridge. This study investigates the acoustic radiation characteristics and mechanism of the box-girder bridge including low-frequency vibrations below the hearing threshold. The foregoing is examined in terms of natural vibration characteristics, vibration responses of the bridge under nonlinear train–track dynamic interactions, and structural noise radiation principle. The results show that the structural resonance, acoustic radiation efficiency, acoustic–vibration coupling in the bridge cavity, and severe train-induced vibrations play important roles in the acoustic radiation of the box-girder bridge. Under moving train loads, bridge vibrations are mainly in the 80- to 100-Hz frequency range and cause distinct noise radiation. Moreover, the low-frequency (20 Hz) train-induced vibrations of the bridge can generate distinct low-frequency noise. Additionally, the box-girder bridge cavity induces acoustic–vibration coupling, which can aggravate the noise radiation on both sides of the box-girder bridge.