NEHRP Clearinghouse
- Title
- Experimental Testing of an Energy-Absorbing Base Isolation System.
- File
- PB81154072.pdf
- Author(s)
- Kelly, J. M.; Skinner, M. S.; Beucke, K. E.
- Source
- National Science Foundation, Washington, DC.; Malaysian Rubber Producers' Research Association, Brickendonbury (England)., October 1980, 73 p.
- Identifying Number(s)
- UCB/EERC-80/35
- Abstract
- The results of an experimental study of an aseismic base isolation system are described in this report. Commercially produced natural rubber bearings and tapered steel energy-absorbing devices are the primary components of the base isolation system. The steel energy-absorbing devices span the natural rubber bearings and connect the foundation to the base of the structure. Structural integrity under low-intensity excitations, such as those produced by wind forces, is maintained since the cantilever device remains stiff up to a predetermined level of loading. Once this level of loading has been exceeded, the devices yield and the natural rubber bearing base isolation system operates to isolate the structure from the damaging effects of high-intensity ground motion. Since the action of the energy-absorbing device is elastic-plastic, the performance of the isolation system is enhanced by the introduction of considerable hysteretic damping into the system upon yielding of the devices. After the energy-absorbing device had been subjected to a series of preliminary static tests designed to determine the hysteretic behavior of the device, the natural rubber bearings and devices were incorporated in an 80,000 lb structural model. The model was mounted on a twenty-foot square shaking table and subjected to a range of earthquake ground motion. Relative displacements at the natural rubber bearings were considerably lower with the devices installed, while structural accelerations were not increased significantly. Reduction of the displacements at the bearings of an isolation system such as that described here is necessary to ensure that the bearings remain stable under load. When both the energy-absorbing device and natural rubber bearings were in place, the structural model withstood simulated earthquake ground motions of extremely high intensity.
- Keywords
- Energy absorption; Earthquake resistant structures; Mechanical hysteresis; Structural design; Dynamic response; Buildings; Earthquake engineering; Ground motion; Foundations; Bearings; Natural rubber