Research on local vibrations of bridge deck of UＨPC simply‑ supported box girders subjected to train excitations

Based on field test, the local vibration behavior of a 32 m simply-supported PC box girder under the excitation of high-speed train is analyzed. A coupled vehicle-rail-bridge vibration analysis model is established, the acceleration responses of the bridge at different locations are calculated, and the reliability of the model is verified by comparing with the measured results. The local vibration characteristics of a 56 m simply-supported UHPC box girder is studied by numerical methods, and the vibration responses of two types of bridges under different filtering conditions are compared. The influence of train speed on local vibration of the bridge is analyzed, and the mechanism of high-order resonance of the train and the bridge and its influence on the operation safety are discussed. The results show that the girders exhibit local vibration characteristics at different locations, with the top slab center and the flange edge being the most significant. The local vibration of the UHPC box girder is more intense than that of the PC box girder. The phenomenon that the box girder vibrates more prominently at specific speeds shall be related to the local vibration modes of the deck and the high-order resonance of the train excitations. The local vibration of the PC box girder is mainly influenced by the 6th and 7th resonant speed bands, while the UPHC box girder is mainly influenced by the 3rd, 6th, and 7th resonant velocity bands. © 2024 Chinese Society of Civil Engineering. All rights reserved.