Structure Response Analysis of the Seismic Isolated Buildings in Bucharest City

Abstract

The paper intends to evaluate and analyze the accelerometric data recorded on certain buildings located in the Bucharest metropolitan area, one of the most exposed in Europe, with three strong earthquakes with magnitude MW>7 in the last century. Starting from information comprised by databases for soils and buildings existing in Bucharest, certain types of structures were selected, according to their specificity (old buildings, retrofitted, etc.) and being continuously seismic monitored. The selected three buildings are equipped with seismic isolators and viscous dampers. The response of these structures, at the ground level, subjected to medium intensity earthquakes will be discussed in terms of peak accelerations and spectral accelerations. Based on the currently accepted standpoint that the dynamic response of certain structures subjected to earthquakes is strongly dependent of the ratio between the natural period of the structure and the dominant period at the construction site, a comparative analysis against free-field data is presented. There would be presented the improvement of seismic response of isolated buildings in Bucharest and the reason these buildings were protected choosing this method. The aim is to provide warnings regarding the severity of seismic events, by means of characteristics of the ground motion, gathered from the response spectra, which may be given soon after the seismic event took place. All the data recorded on instrumented structures during two seismic events (MW = 5.5 and MW = 4.8), together with the subsequent analysis, can represent a reference study for future earthquakes with similar magnitude. The integration of near-realtime seismology with performance-based earthquake engineering allows for providing the information useful for earthquake engineers and decision makers and can enhance the mitigation of seismic risk.