The Effects of Near-Fault Field Recordings on Isolated Steel Structures type of lead-Rubber

The aim of this paper was to investigate the effects of near-fault field records on flexural framed steel structures by applying the rubber-lead core type seismic isolators. Therefore, the seismic responses of the steel structures isolated with a fixed base have been compared in order to understand the performance of the seismic isolation. In this regard, steel structures with 4, 8 and 12 stories have been modeled using SAP 2000 software. The catastrophic events that have taken place in the immediate vicinity of the faults are due to the specific characteristics of the area; so, the appropriate accelerometers were selected by studying the effects of the proximity to the site. Moreover, the seismic responses affected by five time history records of the near-fault field were compared. It worth noting that applying the nonlinear time history analysis led to results that are more accurate. Seismic responses such as stories relative displacement, building base shear, potential energy and plastic joints are taken into consideration for the seismic isolators evaluation. The results show that the application of the seismic isolator in a 4-storey steel structure under the record of the near-fault field decreases the seismic responses by 40 percent on average comparing with the fixed base. However, in the 8-storey building, TABAS record has increased the seismic responses by 25 percent on average. Moreover, for a 12-storey steel isolated building, it can be concluded that by including some accelerometers, the seismic isolators had no effects on the reduction of seismic responses.

Keywords:

Steel structures , Rubber-lead isolator , Near-fault field , Non-linear time history