Parametric Analysis of the Combination of Rubber and Sliding Bearings for Seismic Isolation of Steel Structures

Human has always searched for solutions for mitigating the destructive effects of earthquakes on structures. One of the solutions to this problem that is currently under attention is the use of seismic isolation. In this method, a base isolation system is used to increase horizontal flexibility and the fundamental period of the structure so as to escape the range of earthquake destructions. The low damping rubber bearing used in this study demonstrated a linear behavior and adequate stiffness, but low energy dissipation. On the other hand, the sliding bearing demonstrated a high level of energy dissipation and a lack of ability to return to the initial state. The aforementioned isolators are both easy to build. Hence, a combination of these two bearings will yield an economic highlyefficient isolation system. This study was conducted on fourand eight-story structures with 3and 5-span steel moment-resisting frames with an aim to find the optimum combination of the rubber and sliding bearings. SAP 2000 was used for the purpose of the nonlinear response history analysis. Two series of seven-piece accelerograms including near-source and far-source accelerograms were used. The combination of bearings was determined on the basis of far-source accelerograms while the performance of the combination was examined based on near-source accelerograms.