NEHRP Clearinghouse
- Title
- Ambient Vibration Study of Six Similar High-Rise Apartment Buildings.
- File
- PB294022.pdf
- Author(s)
- Kircher, C. A.; Shah, H. C.
- Source
- National Science Foundation, Washington, DC. Applied Science and Research Applications., January 1975, 92 p.
- Identifying Number(s)
- 14
- Abstract
- Two 12-story high-rise apartment buildings and four 8-story high-rise apartment buildings in Escondido Village on the Stanford University Campus were analyzed to determine their dynamic characteristics. The ambient vibration analyses performed on the buildings produced a collection of power spectral density functions for each building. Although higher modes were undoubtedly present in the power spectral density plots, in general, only the fundamental mode could be consistently identified. An estimate of the percent of critical damping associated with the fundamental mode was calculated for the four 8-story buildings. A mathematical method for comparison of two power spectral densities based on the definition of the correlation coefficient was developed. Pairs of power spectral density plots, as displayed in both the linear magnitude scale and logarithmic magnitude scale, were then compared using this mathematical method. Comparison results conclude that: (1) the method of ambient vibration analysis used produces accurate and reliable results; (2) after enough individually measured and calculated power spectral density functions are averaged together, the resulting power spectral density function is representative of a stationary process; (3) power spectral density plots obtained at different floor levels for the same accelerometer direction may not appear similar unless the overall modal vibrations are sufficiently stronger than any local points of energy transfer; and (4) the buildings analyzed of identical design may often be slightly different in their natural frequencies, and that this slight difference can be accurately determined by this method of ambient vibration analysis.
- Keywords
- Wind pressure; High rise buildings; Vibration; Spectral energy distribution; Damping; Earthquake engineering; Resonant frequency; Power spectra; Apartment buildings; Earthquakes; Dynamic structural analysis