NEHRP Clearinghouse
- Title
- Measurement of Structural Response Characteristics of Full-Scale Buildings: Comparison of Results from Strong-Motion and Ambient Vibration Records.
- File
- PB93113579.pdf
- Author(s)
- Marshall, R. D.; Phan, L. T.; Celebi, M.
- Source
- Geological Survey, Menlo Park, CA. Branch of Engineering Seismology and Geology., October 1992, 87 p.
- Identifying Number(s)
- NISTIR-4884
- Abstract
- The report 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. The buildings represent a range of construction materials, structural systems, foundation systems and building dimensions. Results of the analyses are compared with similar analyses carried out on strong-motion response records obtained from the same buildings during the earthquake. 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 corresponding 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. The lower bound of damping estimates obtained from strong-motion response records in the study is consistent with published data. 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.
- Keywords
- Structural vibration; Loma Prieta Earthquake; Earthquake damage; Dynamic response; Data acquisition; Earthquake engineering; Buildings; Vibration damping; San Francisco (California); Soil-structure interactions; Displacement; Signal processing; Seismic effects; Earthquakes