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Organization Title

OSMS 93-07

"Analysis of Records From Four Base-Isolated Buildings During Low Levels of Ground Shaking"

by M.J. Huang, P.K. Malhotra and A.F. Shakal

Huang, M.J., P.K. Malhotra and A.F. Shakal (1993). Analysis of Records From Four Base-Isolated Buildings During Low Levels of Ground Shaking. Proceedings of Seminar on Seismic Isolation, Passive Engery Dissipation, and Active Control, Volume 1. Applied Techonology council, ATC 17-1, 1993, p.319-330.

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Introduction

Low-level acceleration records wore obtained from four base-isolated buildings during recent earthquakes. The buildings are 2, 5, 8, and 9 stories in height. The distances from these buildings to the earthquakes, which include the 1992 Landers, the 1992 Big Bear and the 1991 Sierra Madre events, range from 28 to 163 km. The peak accelerations at the foundation level of the buildings were between 0.02 g and 0.14 g. The acceleration responses of the buildings were as high as 0.19 g at the roof.

The drifts between the roof and the base of the superstructure and the relative displacements across the isolators for each building were derived from the Landers earthquake records. The results show that the 2-story building had negligible drift and its structure above the isolator responded almost like a rigid body during low-level shaking. On the other hand, the drifts for the other three buildings were not negligible. The deformations of the isolators for these four buildings range from 0.8 to 1.6 cm, which are much smaller than the design values, and the fundamental periods are slightly longer than the fixed-base periods.