NEHRP Clearinghouse
- Title
- Experimental Testing of a Friction Damped Aseismic Base Isolation System with Fail-Safe Characteristics.
- File
- PB81148595.pdf
- Author(s)
- Kelly, J. M.; Beucke, K. E.; Skinner, M. S.
- Source
- National Science Foundation, Washington, DC., July 1980, 62 p.
- Identifying Number(s)
- UCB/EERC-80/18
- Abstract
- An experimental study of a Coulomb friction damped aseismic base isolation system with fail-safe characteristics is described in this report. The base isolation system utilized commercially made natural rubber bearings and a skid system which comes into operation at preset levels of relative horizontal displacement between the structure and the foundations. The fail-safe skid provides hysteretic damping and prevents failure of the isolation system in the event of displacements larger than those assumed in the original design. The isolation system can be designed for an earthquake which can be reasonably expected within the lifetime of the structure; in the event of an earthquake of unanticipated intensity the fail-safe system will prevent collapse of the structure. The testing of the system involved an 80,000 lb model, approximately 1/3 scale to a real structure mounted on the 20 ft x 20 ft shaking table at EERC and subject to a variety of earthquake inputs. The results show that the hysteretic effect of the fail-safe system does not greatly increase the accelerations experienced by the structure but considerably reduces the relative displacements at the isolation bearings. The action of the fail-safe system was tested by using an earthquake input that produced a resonant response in the isolated mode of the model. The stability limit of the isolation system was exceeded and the bearings failed but complete failure of the isolation system and thus collapse of the model was prevented by the fail-safe system. The implementation of the system in full scale structures poses no technical or construction problems.
- Keywords
- Elastomers; Earthquake resistant structures; Sliding friction; Mechanical hysteresis; Structural design; Dynamic response; Buildings; Earthquake engineering; Coulomb damping; Foundations; Bearings