TECHNOLOGY AND CASE STUDY FOR ANALYSIS OF VIBRATIONS AND RESONANCES OF POPULATED BUILDINGS

The determination of the building frequency resonances and mode shapes is usually undertaken at the design phase. These parameters are critical for the prediction of the vulnerability and vibration performance of the building due to potential seismic or severe wind loading. An experimental verification of the design parameters can be accomplished after the construction is completed, but before the building is populated. Mechanical, electro-magnetic or hydraulic actuators are used for this purpose. However, these tests are expensive and thus are not commonly used in the case of residential buildings. Wind loading and/or some residential activities offer an alternative means as a no-cost vibration source that can be used to collect information about the building vibration behavior and shape modes. In addition, these sources are convenient to use as they require simple recording equipment and can be performed even after the population of the building without disturbance or inconvenience to the residents. In this study, a simple but efficient procedure is developed for data acquisition and processing. The data acquisition system consists of three-component seismometers Mark Products L4-3D and a portable seismic station GEODE. A procedure and software for data processing have been developed in MS Excel and VB environment. This procedure allows animating and analyzing the first and second vibration modes of the building as well as the torsional resonances using the measured response to wind loading and residential activities. The developed procedure allows mitigating the influence of the spontaneously increasing sharp spikes of residential vibrations and to convert the original records into more even form without affecting the phase relations between all recorded components. This procedure allows the representation of vibrations at the first, second and torsional modes of the building as non-disturbed vibrations from elastic oscillators.