NEHRP Clearinghouse

Title
Experimental Evaluation of Seismic Isolation of Medium-Rise Structures Subject to Uplift.
File
PB91217950.pdf
Author(s)
Griffith, M. C.; Kelly, J. M.; Coveney, V. A.; Koh, C. G.
Source
National Science Foundation, Washington, DC., January 1988, 181 p.
Identifying Number(s)
UCB/EERC-88/02
Abstract
Earthquake simulator tests were performed on a base-isolated 1/5-scale 7-story reinforced concrete structure with a height-to-width ratio of 1.23. The scale model had been previously tested to failure as a fixed base structure, so it had to be modified to accept the base isolation devices as would be required in a rehabilitation project. Lightweight, low-cost bearings were tested to determine whether such bearings would be suitable for base isolation of smaller structures and houses in less well developed countries where earthquakes pose a major hazard. The test results were compared with values given by the tentative base isolation design provisions proposed by the seismology committee of SEAONC. The study found that base isolation of medium-rise structures provides significant reductions in story and base shears and story accelerations, but the shear connection between the bearing and the column must be maintained during column uplift. In addition, the favorable test results indicated that the rehabilitation of the damaged structure was successful. The performance of the lightweight bearings was nearly identical to that of the more conventional sets used, except that they appeared to be slightly more flexible in shear. The use of lightweight bearings is particularly promising for base isolation of low-cost housing.
Keywords
; Buildings; Vibration isolators; Earthquake resistant structures; Earthquake engineering; Bearings; Simulators; Structural vibration; Earthquakes; Loads (Forces); Vibration damping; Columns (Supports)