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Full-Scale Measurement of Building Response to Ambient Vibration and the Loma Prieta Earthquake.


pdf icon Full-Scale Measurement of Building Response to Ambient Vibration and the Loma Prieta Earthquake. (536 K)
Marshall, R. D.; Phan, L. T.; Celebi, M.

Earthquake Engineering Research Institute. Earthquake Awareness and Mitigation Across the Nation. U.S. National Conference, Fifth (5th). Proceedings. Volume 2. July 10-14, 1994, Chicago, IL, 661-670 pp, 1994.

Keywords:

earthquakes; vibration; data analysis; high rise buildings; office buildings; commercial buildings

Abstract:

This paper describes the collection and analysis of ambient vibration data from five buildings in the San Francisco Bay area that experienced strong shaking during the Loma Prieta earthquake of October 17, 1989. Results of data analyses show that, while the lower modes of vibration can be reliably identified from ambient vibration records, the frequencies of these modes are in each case higher than the frequencies derived from strong-motion response records. When soil-structure interaction is involved, the strong-motion modal frequencies may range from 70 to 80 percent of the corresponding values extracted from ambient vibration records. Estimates of structural damping derived from ambient vibration data are substantially smaller than those derived from strong-motion data and are consistent with predictions of a damping model based on forced vibration tests. Where soil-structure interaction is a significant factor, the overall damping for strong-motion response may be 3 to 4 times the indicated lower bound.