Vibrational and acoustical performance of concrete box-section bridges subjected to train wheel-rail excitation: Field test and numerical analysis

Abstract

For the sustainable development of high-speed railway (HSR) networks, it is becoming increasingly important to tackle usability problems, one of which is the bridge noise generated by high-frequency vibrations of bridge members owing to train wheel-rail excitation. Although concrete box-section bridges predominate in HSR infrastructures, their vibrational and acoustical performance has not been well studied. Field tests on two concrete box-section bridges, one dual-track and the other single-track, are carried out simultaneously during high-speed train passbys. Time-history and spectral characteristics of vibration velocity levels (VVLs) and sound pressure levels (SPLs) are measured and analyzed. Measured data show that the highest peaks of VVLs and SPLs for dual and single-track bridges appear at 50 and 63 Hz, respectively. High-frequency vibrations are independent of longitudinal location for bridges with uniform cross-section. The average difference between the magnitudes of VVLs (with a reference velocity of 10_9 m/s) and SPLs (with a reference pressure of 2_10-5 Pa) is about 28 dB at each frequency. A train-track-bridge dynamic interaction model is applied to determine the vibration of bridge members and the statistical relation between VVL and SPL is used to estimate the near-field bridge noise. The computed results match the measurement results. The cross-sectional bending vibration modes of box-section bridges are of two types: a top-slab-dominated mode and a bottom-slab-dominated mode. Numerical analyses show that the levels of vibration and associated noise are jointly determined by the wheel-rail contact force and cross-sectional bending vibration modes, which reach their highest peaks when the modal frequencies coincide with the frequencies of the wheel-rail contact force at high values. Adjusting the cross-sectional bending vibration modes to the frequency range of the wheel-rail contact force at low values is a feasible method to mitigate bridge vibrations and noise; for example, numerical results show that the addition of a third web in the center of the bridge cross section is effective.