Modal characteristics of vertical vibration in typical steel frame structures under road traffic loads: actual measurements and finite element model update

The increasing expansion of urban transportation networks has significantly amplified structural vibrations transmitted to adjacent buildings, particularly in the vertical direction. While vertical modal characteristics fundamentally govern building responses to such excitations, the underlying deformation mechanisms remain insufficiently understood. Therefore, this study aims to reveal the interaction mechanism of the components during vertical vibration of a steel frame structure under road traffic loads, through field measurements and numerical analysis. A novel model updating method based on horizontal components modal matching was also developed, successfully enhancing the accuracy of numerical analysis. Key findings reveal two characteristic vertical vibration patterns sharing common interaction mechanisms but differing in spatial manifestation: (1) global coordinated deformation modes where flexural beam-slab motion systematically induces column axial straining throughout the structure, and (2) locally dominated deformation modes where architectural unique configurations trigger beam-slab bending in specific regions. The identified deformation patterns directly explain observed vibration amplifications, particularly at upper floors and geometrically irregular zones. The findings of this study have universal significance, providing valuable insights into the vibration pattern of steel frame structures under road traffic loads and offering theoretical guidance for identifying locations with excessive risk and designing vibration control devices.