A Probabilistic Model for the Amplification of the Vibration Response of Railway Bridges Due to Random Track Unevenness in High-Speed Traffic

In combination with the moving train, track irregularities have a significant influence on the structural response of railway bridges. Compared to the ideal case of perfect track geometry without any irregularities, an amplification of the response is observed. This paper proposes a probabilistic model to predict this dynamic response amplification of railway bridges due to random track irregularities when subjected to high-speed trains. The developed regression model, based on a parametric numerical study, provides the mean and standard deviation of the dynamic response amplification separately for bridge deflection and acceleration, since large differences are found for these vibration variables. Depending on the span, mass, fundamental frequency, and damping coefficient of simply supported bridges, dynamic response amplification statistics are approximated for a range of train speeds and different track qualities. The proposed model estimates the dynamic response amplification due to random track irregularities at predefined exceedance probabilities, and a customized amplification factor is determined that is consistent with the semi-probabilistic safety concept used in structural design. An application example shows the superiority of this model compared to the commonly used code-based approach.