Henri Gavin, Ph.D., P.E., Associate Professor
[ Project Summary ]
[ Numerical Models and Software ]
[ Physical Experiments ]
[ Education ]
[ Publications ]
[ Presentations ]
[ Acknowledgments ]
The functionality and serviceability of hospitals, emergency-response centers, and data centers immediately after an earthquake depends not only on the performance of the structural system, but also on the performance of the building contents. Non-structural systems, and telecommunications equipment in particular, can be particularly fragile to seismic effects. 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. Typically these equipment isolation systems (EIS) are of a friction-pendulum, or rolling-pendulum type, and consist of sets of shallow steel dishes containing a hard steel ball. Rolling EIS's perform extremely well during low-level seismic events, however, 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. The primary goal of this project is to model, and assess the role of damping systems to extend the strong performance of rolling isolation systems for long period excitations.
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 2008, provide a unique opportunity to assess the true seismic vulnerability of the EIS's to near-fault effects.
This project aims to answer important questions related to seismic protection of critical sub-systems: * What is the maximum level of seismic protection that rolling isolation systems can provide to fragile equipment for near-fault ground motions and far-fault motions? * What is the sensitivity of rolling equipment isolation systems to the large displacement demands of near-fault ground motions? * Can elastomeric or frictional damping effectively attenuate pay-load accelerations and isolator drift?[ Top ]
This material is based upon work supported by the the Civilian Research and Development Foundation for the Independent States of the Former Soviet Union (CRDF) under Award No. MG1-2319-CH-02 and by the National Science Foundation under Grant No. NSF-CMMI-0704959 (NEES Research), Grant No. NSF-CMS-0402490 (NEES Operations). and Grant No. NSF-CMMI-1436015. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundatioon. The researchers acknowledge assistance from Dr. R. Fleischman and Dr. J. Restrepo in facilitating the payload testing aspects of this work.[ Top ]