by M.J. Huang, A.F. Shakal and R.B. Darragh
Huang, M.J., A.F. Shakal and R.B. Darragh (1994). Recorded Strong-Motion Data From the Northridge, California Earthquake of January 17, 1994. Proceedings of the Ninth Japan Earthquake Engineering Symposium • 1994 Volume 3. Dec. 1994, Tokyo, Japan, p. I-16 - I-25.
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Some of the highest acceleration ever recorded at structures and ground response sites occurred in the Northridge earthquake. The peak ground accelerations are greater than most existing attenuation models would have predicted. The thrust mechanism of this event as well as its location under a metropolitan area may have contributed to the number of high acceleration recordings. Some vertical accelerations were larger than the horizontal, but in general this event fits the pattern observed in previous earthquakes. Processed strong-motion records show significant differences in acceleration and velocity waveforms and amplitudes across the San Fernando Valley.
Analysis of processed data from several buildings in the San Fernando Valley indicates that stiff, short-period buildings such as shear wall buildings experienced large forces and relatively low story drift during the Northridge earthquake. On the other hand, flexible, long-period buildings such as steel or concrete moment-frame buildings experienced large story drifts. For this earthquake, accelerations did not always amplify from base to roof for flexible structures like the moment-frame buildings, but the displacements were always larger at the roof. The records from a base-isolated building indicate that high-frequency motion was reduced significantly by the isolators, which only deflected 3.5 cm.