Band-gap analysis of urban rail transit viaducts and parameter design of vibration-isolation bearings

Urban rail transit (URT) viaducts are subjected to long-term train-induced vibration, yet conventional train-bridge dynamic analyses rarely reveal how the parameters of bridge bearing control vibration transmission from the perspective of wave propagation. This study proposes a band-gap-analysis-based design method for vibration-isolation bearings in periodic URT viaducts. A train-track-bridge dynamic interaction program is first used to obtain the wheel-rail interaction forces, which are then introduced into a frequency-domain analytical model of a periodic bridge established based on Bloch’s theorem and the Fourier transform. The model is verified against an analytical solution for a periodic simply supported beam bridge. Taking the viaduct of Beijing Metro Line 13 as a case study, the characteristic wave modes, complex-wavenumber characteristics, and attenuation curves are analyzed to select the vertical stiffness and damping of the bearings. The results show that reducing the bearing vertical stiffness and increasing the equivalent damping can enhance spatial wave attenuation and reduce vibration transmission between spans. For the investigated viaduct, the suitable bearing parameters are identified as a vertical stiffness of 1.0 × 10 8 N/m and an equivalent damping coefficient of 6.0 × 10 6 N·s/m. Frequency- and time-domain comparisons further confirm that the recommended bearing system suppresses high-energy vibration components while satisfying displacement limits. The proposed method provides a theoretical and practical basis for vibration-isolation design of periodic urban rail transit viaducts.