Global vertical resonance phenomenon between steel building and human rhythmic excitations

• Human rhythmic activities affect the global vertical vibrations of a building.
• Vibration tests and time history analyses were conducted for investigation.
• The vertical vibrations of building are due to resonance phenomenon.

An abnormal vibration accident caused by human rhythmic excitations occurred in the upper floors of a 39 story steel building in Seoul, Korea. In this paper, the effects of human rhythmic excitations on the global vertical vibration of a high-rise steel building were evaluated. Experimental tests were conducted to measure the natural frequencies and the floor acceleration responses of the building. Also, using three-dimensional finite element model, the vertical natural frequency of the building was estimated by conducting modal analysis, and time history analyses were performed by applying the various human rhythmic excitations to the floor slab of a fitness center in the 12th floor of the building. The modal analysis results verified that the building has the global vertical vibration mode of 2.7 Hz natural frequency which was identified by experimental tests. The vertical accelerations of the floors resulting from the time history analyses also agreed very well with the experimental results. Finally, it was concluded that the resonance phenomenon between building structure and human rhythmic excitations with the step frequency of 2.7 Hz caused the abnormal vertical vibration accident of the building.