High-Efficiency Dynamic Analysis of Heavy-Haul Train-Simply Supported Bridge Interactions: Theoretical Modelling and Experiments

Double-Track Bridges (DTBs) are widely used in heavy-haul railways to accommodate bidirectional traffic. Under asymmetric train loading, DTBs may experience pronounced torsional deformation and unbalanced bearing reactions, which can intensify train–track–bridge dynamic interaction. At the same time, the large structural scale of DTBs requires high computational efficiency. This study investigates the dynamic interaction characteristics of the Heavy-Haul Train-Double-Track Bridge System (HTDTBS) by developing a high-efficiency coupled dynamics model. The governing vibration equations of the heavy-haul train subsystem are derived from the D’Alembert principle. A multi-span double-track simply supported bridge is modeled by the Component Mode Synthesis (CMS) method to enable efficient simulation of large-scale bridge structures. The HTDTBS is coupled through nonlinear wheel–rail contact and equivalent track–bridge connection relationships. Based on this framework, the dynamic responses of the HTDTBS are examined in the time and frequency domains through theoretical analysis and field testing, and the measured data are used to validate the proposed model. Parametric analyses are then conducted to identify key design parameters that improve the dynamic performance of the HTDTBS. The results indicate that good consistency is observed between the simulation outputs of the established dynamic model and field test data. Asymmetric loading from heavy-haul trains generates notable torsional responses in DTBs. The rotation angle under loaded train conditions exceeds three times that under empty conditions. To guarantee favorable dynamic performance of DTBs, the recommended stiffness values are 140–180[Formula: see text]MN/m for rail fastener pads and over 800[Formula: see text]MN/m for bridge bearings.