Clarification of the effect of high-speed train induced vibration on a railway steel box girder bridge by monitoring using Laser Doppler Vibrometer

摘要

The effect of train-induced vibrations and the train speed on local stresses at each part of a steel box girder bridge was studied by field measurement. The field measurement was conducted using conventional sensors for train induced vibration and laser Doppler vibrometers for ambient vibration. The data acquired were analyzed to identify the natural frequencies and the changes based on the retrofit in the modal shapes of the railway bridge. The results show that vibrations at the lower flange of the main girder increased the local stresses causing damage. Next, the study shows that the vibration depends on the cyclic external load induced by train speed. Finally, train induced vibration phenomena was explained using simple analytical model combined with measurement and influence of train speed increase on local vibration was predicted.