Field measurement of the dynamic responses of a suspended monorail train-bridge system

This work presents an integrated and large-scale field measurement of the dynamic responses of a suspended monorail train-bridge system, which is rarely reported. This experimental train uses a high-capacity lithium battery for the operation. The maximum running speed of the train is up to 60 km/h. The experimental line was constructed on a full-scale steel bridge composed of a straight section, curved sections with different horizontal radiuses and a slope section of 60 parts per thousand. First, the train-bridge dynamic responses under different conditions are extracted based on the field test. Then, the car-body accelerations under different train speeds and bridge sections are analysed in detail, and the running stability of the vehicle is assessed by adopting the Sperling index. By comparing the dynamic responses of the train-straight bridge interaction and the train-curved bridge interaction, some significant discrepancies and interesting phenomena could be found. Subsequently, based on the test data, the vertical rotation angles of the beam end and the dynamic amplification factors of the bridge displacements under different vehicle speeds and bridge sections are obtained, and then the vibration levels of the bridge under different conditions are evaluated. Finally, by analysing the frequency spectra of the dynamic responses, the dominant frequencies of the acceleration signals of this monorail vehicle and bridge subsystems are revealed; in addition, the sensitive wavelengths that influence the running stability of the vehicle are found. These measurement results may provide valuable guidance for the design of the suspended monorail system and numerical model validation.