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Published 1996 | public
Book Section - Chapter

The drift demand spectrum and its application to structural design and analysis

Iwan, W. D.

Abstract

A new measure of the demand of strong earthquake ground motion on structures is described. This measure gives the maximum inter-story drift ratio demand associated with a given earthquake ground motion. A uniform linear shear-beam model is employed to calculate the maximum inter-story drift. The drift demand can be computed algebraically using wave propagation techniques and no differential equations need be solved. The drift demand may be graphed as a function of structural period and damping, just as in the case of the Response Spectrum. This new spectrum is referred to as the Drift Spectrum. The Drift Spectrum and Response Spectrum contain different but complementary information. Examples of Drift Spectra for near-field recorded ground motions from the Northridge and Hyogo-ken Nanbu earthquakes are presented. The concept of the linear Drift Spectrum is extended to account approximately for effects of localized yielding associated with high inter-story drift. It is shown that the drift demand arising from recently recorded near-field ground motions, as indicated by the Drift Spectrum, exceeds the capacity of many current steel frame beam-column connections

Additional Information

Copyright © 1996 Elsevier Science Ltd. The author thanks Mr. Qun Gu and Mr. Luo-Jia Wang for their assistance in the numerical studies reported in this paper. The author is also indebted to the Los Angeles Department of Water and Power, Lindvall Richter Benuska Associates and Agbabian Associates for supplying uncorrected data for the Sylmar Converter Station record. The study reported in this paper was supported in part by grants from the National Science Foundation and the SAC Joint Venture Project on the failure of steel frame joints in the Northridge earthquake. The opinions expressed are those of the author and do not necessarily reflect those of any sponsor.

Additional details

Created:
August 20, 2023
Modified:
October 19, 2023