Preliminary Study Of Near-fault Seismic Response Mechanism On High Damping Base-isolated Structure

Earthquake is one of the very serious harm to humans and is difficult to predictdisasters, with catastrophic and unexpected features. Research on the seismic design ofengineering structures has been a focus of research. Near-fault ground motionssignificantly different from the normal vibrations of far-field characteristics, but also onthe structure caused by the more obvious. Because of good damping effect, isolationtechnique has been widely used. Lead rubber bearing has been widely used,but it willlead to structural eccentric and environmental pollution. Since a single high-performanceand no pollution, damping isolator has been used more and more widely. This thesis is astudy in contrast to near-fault and far field ground motions of these two isolatedstructures.In this paper, using the finite element software SAP2000,we have established withthe same upper structure of non-isolated structure, high damping isolated structure andlead-isolated structure. High damping isolated structure is based on lead-isolatedstructure, that ensure an equivalent level of isolation layer the same as the averagestiffness. In the same time, its equivalent damping ratio has been greatly improved. Bynonlinear dynamic time history, we compare the dynamic response of these threestructures in the far-field ground motions and near-fault ground motions.In general far field motions, lead isolated structure damping effect is better than highdamping isolation structure. In the near-fault ground motions, the two isolated structureis very close to the damping effect. With the improvement of the equivalent dampingratio, high damping isolation structure compared with lead core isolation structure,showing a smaller reaction in the lower part of the structure, a stronger reaction in theupper structure.