STUDY ON TRAIN-INDUCED VIBRATION CHARACTERISTICS AND MITIGATION MEASURES OF OVER-TRACK BUILDINGS

Over-track buildings have gained a significant attention in recent years due to their efficient use in space and convenient transportation conditions. Current research on train-induced vibrations in over-track buildings primarily focuses on the underground tunnel or ground floor modes, with relatively limited investigation into novel elevated development modes. To study the vibration characteristics and mitigation measures during subway train operations for these novel over-track buildings, a typical engineering project was selected as the research object. Field measurements were initially conducted to quantify the vibration loads induced by subway trains. Subsequently, a comprehensive analysis was undertaken through the numerical simulations and field measurements to investigate the propagation characteristics, influencing factors, and the effectiveness of the corresponding mitigation measures on vibrations in the over-track building. The analysis results show that train-induced vibrations are predominant in the vertical direction, with frequencies primarily ranging between 25 Hz and 60 Hz. As the vibration wave propagated upward along the floors, vibrations at the mid-span of girders and slabs first decreased and then increased, while vibrations at the bottom of columns continuously increased. An analysis of influencing factors demonstrates that increasing the overall structural stiffness or adjusting the impedance ratio between floor slabs and columns can reduce vibration transmission. The installation of three-dimensional damping bearings at the bottom of the structure can significantly reduce the propagation of vibrations and the relevant vibration reduction rate can reach about 68.4%. These findings provide a reference for the vibration analysis and vibration isolation design for over-track buildings.