Low-frequency noise radiation from traffic-induced vibration of steel double-box girder bridge

Low-frequency noise radiated from bridge vibrations has been reported as an environmental noise problem in many countries. In order to investigate the mechanism of low-frequency noise radiated from bridge vibration, a steel bridge with a double-box is adopted for study. Modal parameters of the bridge, including natural frequency, damping ratio and mode shape, are identified from field tests by a combination of Eigensystem Realization Algorithm and Fast Fourier Transformation. Then the grillage model of the bridge is established and physics parameters of the model are updated by genetic algorithm according to identified natural frequencies. The dynamic response of the bridge by the action of a moving vehicle is calculated and assumed as the sound source of low-frequency noise. Then low-frequency noise due to bridge vibration is estimated according to sound wave propagation theories. The validity of the numerical method is verified through comparison with experimental results. Furthermore, noise reduction methods are proposed and corresponding effects are discussed. Results show that numerical simulation is feasible in assessing low-frequency noise due to traffic induced vibration of a bridge, which offers a possible way for environmental assessment as well as being a good reference for noise reduction design of bridges. The deck plate of the bridge is the primary source of low-frequency noise. Hence, increasing the stiffness of a deck plate is effective for noise control. Improving the road roughness can also reduce low-frequency noise.