Local ground effects in near-field and far-field areas on seismically protected buildings

• Three types of r.c. buildings with 3, 7 and 15 floors (with different period ranges) protected with energy dissipaters.
• Far-field and near-field ground motions recorded on stiff soil and on common soil have been considered.
• Buildings seismically protected and braced buildings have been considered in the non-linear analysis.
• Buildings are kept in the elastic field and nonlinearities are concentrated in the dissipators.

This paper presents a 2-D numerical study on the nonlinear seismic response of buildings equipped with two types of energy dissipators, which dissipate energy activating two different mechanisms. Three types of reinforced concrete buildings with 3, 7 and 15 stories, respectively representative of short, medium and long period ranges, are considered. Dissipators are placed on steel diagonal braces at all the floors; their sliding threshold (or yielding) forces are taken as 100% of those generated by the equivalent static lateral forces recommended by EC8 for a ductile moment resisting frame. The input consists of six recorded earthquakes, 3 representatives of near-field earthquakes and 3 representatives of far-field earthquakes. Each input is considered once from the bedrock and once filtered by a common ground with several layers of different thicknesses. The responses of the buildings are discussed and compared emphasizing the filtering effects produced by the ground.