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Title: Study of ground motions at soil sites during two California earthquakes
Authors: Rensselaer Polytechnic Institute. Department of Civil Engineering.
Dobry, R. (Ricardo), 1922-
Singh, Sohan.
Bond, William E.
Keywords: Accelerograms
Ground motion
Earth movements
Publisher: Geotechnical Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; GL-79-22.
Description: Miscellaneous Paper
Abstract: Nine strong motion accelerograms recorded at rock and soil stations during two California earthquakes are analyzed using recently developed processing techniques. These techniques study the characteristics of the records in the time domain, including graphs of the buildup of energy of the horizontal acceleration with time, the variation with time of the RMS horizontal acceleration, and the variation with time of the angle, ϕ₁, between the principal axis of the ground acceleration and the vertical axis. The examination of these graphs allowed the determination of the times, t₁ and t₂, corresponding to the beginning and end of the strong part of each record. During this strong part, ϕ₁≅ 90°, which suggests that the motions at both rock and soil sites are caused mainly by SH-waves. The comparisons of the graphs showed that the wave arrivals are generally consistent between stations during the strong part but that some soil accelerograms have additional significant motions after t₂. The consistency of wave arrivals during the strong part was especially good for the 1971 San Fernando records in the Pasadena Area. There, the strongest wave arrival occurred at all four stations considered, approximately 3 seconds after the first S-wave arrival. Several one-dimensional site response simulations were performed at some of the soil stations studied, using the equivalent linear approach. The results showed that the simulated soil accelerations essentially preserve the time domain features of the input rock motion. One consequence of this was that the simulations predicted reasonably well the characteristics of soil motions in the strong part, but did not predict the additional soil motionc after t₂.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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