Dynamic Response and Running Safety of a Four-Track 4 × 40 m Continuous Rigid-Frame Bridge Under Wind–Vehicle–Bridge Coupling

Continuous rigid-frame bridges with standardized spans are increasingly favored in high-speed railway networks owing to their stable structural mechanics and economical lifecycle maintenance. Despite their widespread adoption, comprehensive quantitative analyses detailing wind–vehicle–bridge coupled dynamic interactions remain notably sparse, particularly under the combined excitations of high-speed transit and overall track geometry deviations, which incorporate both stochastic irregularities and deterministic long-term deck creep. To bridge this knowledge gap, the present study investigates the dynamic stability and operational safety of a 4 × 40 m continuous rigid-frame bridge featuring a specialized parallel double-box cross-section. Initially, the tri-component aerodynamic force coefficients for this coupled system are extracted utilizing computational fluid dynamics (CFD) simulations. Subsequently, a three-dimensional wind–vehicle–bridge interaction model is formulated. This governing dynamic framework integrates turbulent wind pressures and track geometry deviations as external excitations. The mathematical derivation of this model is fundamentally based on d’Alembert’s principle. Utilizing this advanced model, the transient dynamic responses of traversing CRH6 trainsets are systematically evaluated across a comprehensive matrix of environmental lateral wind velocities, ranging from 0 to 30 m/s, and operational speeds varying between 120 and 200 km/h. The computational outcomes demonstrate that both the vehicular accelerations, in lateral and vertical directions, and the structural deflections strictly satisfy stringent statutory safety limits across all simulated environmental scenarios. This ensures satisfactory ride comfort and running stability for the high-speed trains. Ultimately, this research substantiates that the investigated bridge topology maintains an adequate dynamic safety margin even under severe crosswinds. It does not constitute a kinematic bottleneck for the maximum operational speed of the railway corridor under the modeled conditions. These insights establish a solid theoretical foundation for the aerodynamic design and safety evaluation of analogous high-capacity rail infrastructure.