Dynamic simulation and critical assessment of a composite bridge in high-speed railway

Evaluation of critical responses of a bridge including resonances in high-speed (HS) railway is a dominant issue in order to confirm the structural safety of bridge and the stability of ballast on bridge deck. In numerical way for critical assessment, it is important to make a sophisticated numerical model and considering the variation of actual properties of structural members. This study proposed a train-track-bridge interaction model focusing on Sesia viaduct, and calibrated the model properties as matching these modal characteristics and dynamic responses to measured ones. By the numerical and experimental comparison, calibrated model could reproduce accelerations up to 30 Hz both of on the time and frequency domains accurately. Especially, good agreements on sleeper accelerations can indicate the high reproducibility of interaction force, which is one of key factors of train-track-bridge interaction simulation. Numerical computation by calibrated model clarified that the deck acceleration up to 30Hz increases by seventh and eighth resonances between passing vehicle length and structural modes, not only global third bending or third torsional but also high order local deck modes. In addition, high performance computing technique based on super computer in RTRI was adopted for parametric analysis in order to investigate the requirements to realize highly accurate estimation for the maximum deck acceleration by the numerical way. As the results of parametric study focusing on design assumption, calculation modal order and train/bridge interaction, it was clarified that the design model causes overestimation by twice maximum acceleration on the deck, and the amplification of excitation forces caused by passage on deflected rails, which is considered in high-order modes and train/bridge interaction, is a key factor to achieve accurate deck acceleration evaluation.