NEHRP Clearinghouse

Title: Vibration Properties of Buildings Determined from Recorded Earthquake Motions.
File: PB99106106.pdf
Author(s): Goel, R. K.; Chopra, A. K.
Source: National Science Foundation, Arlington, VA., December 1997, 286 p.
Identifying Number(s): UCB/EERC-97/14
Abstract: Developed first in this investigation is a database on vibration properties - period and damping ratio of the first two longitudinal, transverse, and torsional vibration modes - of buildings 'measured' from their motions recorded during eight California earthquakes, starting from the 1971 San Fernando earthquake and ending with the 1994 Northridge earthquake. To this end, the natural vibration periods of 21 buildings have been measured by system identification methods applied to the motions of buildings recorded during the 1994 Northridge earthquake. These data have been combined with similar data from the motions of buildings recorded during the 1971 San Fernando, 1984 Morgan Hill, 1986 Mt. Lewis and Palm Springs, 1987 Whittier, 1989 Loma Prieta, 1990 Upland, and 1991 Sierra Madre earthquakes reported by several investigators. The 'measured' fundamental periods of moment-resisting frame and shear wall buildings, extracted from the database, are then used to evaluate the empirical formulas specified in present US codes. It is shown that although current code formulas provide periods of moment-resisting frame buildings that are generally shorter than measured periods, these formulas can be improved to provide better correlation with the measured period data. Improved formulas are developed by calibrating the theoretical formulas against the measured period data through regression analysis.
Keywords: Building codes; Seismic design; Shear walls; Structural vibration; Framed structures; Moments; Seismic waves; Rayleigh equations; Dynamic response; Ground motion; Buildings; Earthquake engineering; Transverse waves; Soil-structure interactions; Longitudinal waves; Seismic effects; Torsional vibration; Dynamic structural analysis