| Abstract: | Essential requirements from a base isolation system include wind restraint, stability and fail-safe capacity. A new base isolation system that satisfies all three requirements and possesses other advantages was tested on the earthquake simulator at the University of California under the base of a one-fourth scale nine storey steel structure. The base behaves as fixed for low magnitude inputs. When sliding starts the rubber bearings provide additional stiffness and recentering. Displacements are better controlled than the ones for a purely elastomeric isolation system. Vertical deflections due to large horizontal drift encountered in solely rubber systems are eliminated. The fail safe capacity is provided by tension restrainers installed inside the rubber bearings, and by the constant contact of the base with the sliders. Base shear hysteresis loops are drastically enlarged by the presence of the sliders. |
