Dynamic Compatibility and Frequency-Selective Mitigation Assessment of an Anti-Vibration Spherical Steel Bearing for an 8 × 100m Continuous Steel Truss Railway Bridge

Long-span road–rail steel truss bridges require support-level vibration mitigation without compromising bridge serviceability, train-running safety and comfort, or environmental vibration control. This entirely numerical study establishes coordinated vehicle–bridge interaction (VBI) and vehicle–bridge–soil models for the Wuchang-side 8×100 m continuous steel truss approach bridge of the Baishazhou road–rail Yangtze River Bridge. Ordinary steel bearing and anti-vibration spherical steel bearing (AVSSB) schemes are compared under the same track irregularity, train speeds, and one-to-four-line operating cases. Finite AVSSB vertical stiffness produces only limited modal shifts, reduces the impact coefficient by up to 4.4%, and reduces the selected pier lateral acceleration by up to 13.7%, without a discernible deterioration in the derailment coefficient, wheel-load reduction ratio, carbody acceleration, or Sperling comfort index at the reported precision. Frequency selectivity is important in engineering terms because reducing a narrow medium- or high-frequency component does not necessarily reduce the low-frequency-dominated overall ground vibration index. The practical contribution is therefore a system-level screening procedure; an AVSSB may be adopted as a dynamically compatible support modification when selective structural vibration reduction is required, but the speed and multi-line operating scenarios must still be checked independently for environmental vibration compliance.