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چکیده
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Seismic isolation technology is one of the most efficient and most effective ways to reduce earthquake response. Among these, near-field earthquakes with high speed and pulse condition can cause critical cases in the seismic performance of base isolations. For this purpose it is necessary to design base isolations that have near-field special performance and structural response to maintain the optimal performance. In this paper, damping effect of lead rubber bearing with different periods for the structural response that designed based on notification No. 2009 and 1446 of Japan's regulations, are studied. For this purpose, seismic performance of two steel isolated buildings under near field seismic excitation with nonlinear time history analysis are studied and responses of base isolations displacement, story acceleration, base shear of stories and story drift are taken into account. The results show increasing in damping only lead to undesirable results such as increasing amounts of acceleration response of stories and story drifts under near field excitation. In the isolators under near-field records, if both damping and ductility increase, although displacement in level of the isolators increases, but other parameters such as displacement and acceleration produced in the stories decreased considerably that play an important role in reducing non-structural damage, i.e. the equipment and sensitive facilities.
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