Application of FEM-BEM-PEM Hybrid Random-vibration Method on Low-frequency Structure-borne Noise Prediction of U-shaped Girder in Urban Rail Transit

The U-shaped beam, a novel beam type, is extensively used in urban rail transit due to its ability to block radiation noise from wheel–rail interactions, providing effective noise control at the source. This study aims to investigate the dynamic response and structure-borne noise of a 25[Formula: see text]m concrete simply supported U-shaped girder at a vehicle speed of 80[Formula: see text]km/h, and to assess the effectiveness of novel track vibration damping devices. Grounded in stochastic vibration theory, this study employs pseudo excitation methods (PEM) to obtain the frequency domain response of a finite element model of the U-shaped girder. The structure-borne noise is then analyzed using the acoustic indirect boundary element method (BEM), with frequency-domain responses from PEM as input conditions. The eastern extension section of Nanjing Metro Line 2’s simply supported U-shaped beam is used as a case study for practical and theoretical analyses of dynamic characteristics and structural radiation noise. This study reveals that the sound pressure level of the mid-span section’s bottom plate is higher directly below and above it, while it is lower on either side of the web. Considering the ground reflection effects, sound pressure levels are highly closer to ground reflections. The damping device significantly attenuates vibration noise in the frequency range of 50–200[Formula: see text]Hz, with the bottom plate exhibiting superior vibration reduction effects compared to the web. The predictive method aligns closely with field test results, validating the feasibility of the approach. This study demonstrates that the U-shaped beam effectively controls rail transit noise, and the novel track vibration damping devices significantly reduce vibration noise, particularly in the bottom plate. This research provides valuable insights for noise control in urban rail transit systems.