OSMS 94-29

OSMS 94-29

"Analysis of Records From Four Base-Isolated Buildings During the 1992 Landers Earthquake"

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

Huang, M.J., P.K. Malhotra and A.F. Shakal (1994). Analysis of Records From Four Base-Isolated Buildings During the 1992 Landers Earthquake. Proceedings Volume 1 of Earthquake Awareness and Mitigation Across the Nation. Fifth U.S. National Conference on Earthquake Engineering, July 10-14, 1994, Chicago, Illinois, p. 117-126.

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Introduction

Strong-motion records were obtained from four base-isolated buildings during the 1992 Landers earthquake. The buildings are 2, 5, 8, and 9 stories in height. The distances from these buildings to the Landers earthquake range from 106 to 163 km. The peak accelerations at the foundation level of the buildings were between 0.04 g and 0.11 g. The acceleration responses of the buildings were as high as 0.19 g at the roof.

For each building, the drifts between the roof and the base of the superstructure and the relative displacements across the isolators 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 the Landers earthquake. On the other hand, the superstructure 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 (25 to 40 cm), and the fundamental periods are slightly longer than the fixed-base periods.