engleski

Continuous monitoring of dynamic parameters of the DGFSM building (Zagreb, Croatia)

Continuous broad-band measurements of vibrations on the 3rd floor of the building of the Department of Geophysics, Faculty of Sciences and Mathematics (DGFSM) in Zagreb provided high quality data that enabled monitoring of fluctuations of the building’ s basic dynamic parameters (fundamental frequencies and the corresponding damping). It was found that nonlinear behaviour is present even for the small strains induced by ambient vibrations, which was manifested in measurable reduction of fundamental frequency and increase of damping for larger excitation levels. These effects were also observed in response of the structure to two small local earthquakes which occurred during the observation period. Correlation of the observed long-term wander of dynamic parameters with the change of meteorological elements revealed notable correspondence of the variations of the fundamental frequency and the relative air humidity (which was related to soil saturation, thus causing variability of soil-structure interaction). The damping was found to vary synchronously with the air temperature. The results point to the importance of considering all aspects of nonlinearity of building response even for small strains.

building fundamental frequency; damping in buildings; ambient vibrations; soil-structure interaction; nonlinearity of building response

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