ABSTRACT
In the past decade the wind turbine construction was highly extended all over Europe. But this expansion came also with some special design rules and construction technological problems, especially for location of this class of energy structures in seismic areas. As it is well known, Romania has a high seismic hazard, Vrancea region from Romania being actually the epicenter of major tectonic earthquakes relevant for the Eastern Europe. Therefore, when it comes to wind turbine design and construction in the prone seismic area, it is necessary to consider, apart from the wind action, the seismic action. More than these, the foundation soil conditions should be taken into account, as they directly affect the dynamic characteristics of the tower, in order to avoid the resonance phenomenon. Therefore the knowledge of modal analysis results of the structure, along with time history response considering the past recent earthquakes in the situ, is a relevant source of information in the attempt to evaluate the structural response during life cycle of this system. Considering these arguments, the present paper aims to assess the effects of soils structure interaction upon a wind turbine tower, located in Iasi region, an important hazardous region of Northeastern Romania, considering various earthquake actions typical for this situ. For the earthquake actions some recorded accelerograms of recent earthquakes from 1986 and 1990, for Iasi have been applied. The results of time history analyses applied on a 70 meters tall wind turbine considering 4 different types of soils as supports are presented and discussed, in order to have a better understanding of future behavior based on identification of possible maximum responses of this type of structures under the action of Vrancea’s earthquakes, which may occur during life time cycle functioning.
