Horizontal Resonance of a 13 Story Building Under External Machine Vibrations.

Excessive vibrations seriously affected the comfort of residents living on the upper floors of a high-rise shear walled building in Beijing. The ambient vibration tests were conducted to measure the floor acceleration responses, which were found to contain almost periodic signals likely to be excited by vibration sources with frequency of about 1.5Hz. The transverse vibration levels of the building above the 8th floor are not acceptable as revealed by the one-third octave spectra and weighted acceleration levels according to the 'Standard for Allowable Vibration of Building Engineering' of China. The modal properties of the building are identified by a Bayesian FFT method, indicating that the resonance between the building and the vibration sources caused the excessive vibrations. For comparison, the vibration test of an adjacent building with the same structural design was also conducted, together with modal analysis by the finite element method. It is found that as the story level increases, different trends of amplification in floor root mean square (RMS) acceleration and mode shape component of the two buildings cause different vibration levels. After tests outside the residence community, the main vibration sources were identified to be the working machines in two stone processing factories a few hundred meters away from the building. The vibration tests with measurements in the building and near the vibration sources with different number of machines in the two factories were also conducted. The results show that the vibration levels of the building can be controlled below the acceptance value by reducing the number of machines. [ABSTRACT FROM AUTHOR]