Dynamic interaction analysis between high-speed train and multi-span prestressed concrete box girder bridges

This study analyzes dynamic interaction between high-speed trains and multi-span reinforced concrete box-girder bridges, considering approach embankment stiffness and rail–bridge connection. A finite element model in Midas Civil 2024 simulates the coupled train–rail–bridge system using Eurocode-based train and equivalent-rail representations. Parametric analyses across ranges of embankment stiffness and connection rigidity identify modeling parameters. Subsequently, time-history dynamic analyses are performed on a continuous prestressed concrete box-girder bridge to quantify responses under multiple train velocities. The dynamic impact factor is evaluated for critical components and compared against international provisions to assess applicability to Vietnamese conditions. Results highlight sensitivity of bridge responses to boundary stiffness transitions and connection rigidity, and delineate parameter ranges that limit vibration and amplification at high speed. The study recommends an optimal configuration for approach stiffness and rail–bridge connection, providing a technical basis for safe and efficient design of high-speed railway bridges in Vietnam.