About the Group
In order to mitigate the seismic risk posed to shock and vibration-sensitive equipment, isolation systems have been installed within hundreds of data centers, hospitals, and emergency response centers. During near-fault ground motions (such as ground motions with a long-period velocity pulse) the displacement demand on the isolators are likely to result in the isolation system rolling beyond its limits and could result in impacts or the toppling of equipment. Current seismic qualification standards for equipment protection systems do not require long-period excitation. For these reasons, the current level of seismic risk to isolated equipment in hospitals, data centers, and emergency response facilities is virtually unknown. The Large High-Performance Outdoor Shaking Table (LH-POST) at the UCSD-NEES equipment site is one of the only facilities in the world capable of exerting the long-period high-velocity motions required to assess the behavior of rolling isolation systems under near-fault conditions. Experiments at LH-POST on a precast concrete structure, planned for May 2008, provide a unique opportunity to assess the true seismic vulnerability of the EIS’s to near-fault effects.