DOI: 10.5593/SGEM2015/B13/S5.117


S.F. Balan, B.F. Apostol
Friday 7 August 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-33-9 / ISSN 1314-2704, June 18-24, 2015, Book1 Vol. 3, 903-910 pp

The paper aims to discuss how to mitigate seismic risk through avoiding soil-structure resonance between dominant periods of the location and periods of the structure, starting from actual earthquakes records, using already known data about the fundamental period of vibration of the ground.
It is well known that major damages appear at resonance, when the natural period of structure is equal or very close to the dominant period of the site. For this reason, a correct evaluation of site dominant period is of high importance.
We will focus on the analysis of Bucharest Metropolis foundation soils, where buildings are placed in an exposed area to high seismic hazard. The regions of the south-east and south of Romania are affected mainly by Romania Vrancea strong earthquakes. Only in the XX-th century there have been several major earthquakes.
There are presented methods for computing the oscillation period of the soil and a short review of the methods for computing the oscillating periods of structures. In this respect, we have used the only available record for the 1977 strong earthquake recorded at seismic station INCERC.
An important database of earthquakes was obtained in recent years at NIEP, in the project URbanSeismology, through international collaboration with the University of Karlsruhe - CRC 461.
A map was drawn of oscillation periods for Bucharest. Having this map we know the dominant periods of every important zone in the city and we can judge if a building is suitable for such a zone and the authors opinion is that it is more safe to pick the right building for a zone it suits then to force a non-resonance design in that place.

Keywords : soil structure interaction, fundamental period, earthquakes, spectral response, dominant periods.