Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

Sanaz Rezaeian; Yousef Bozorgnia; I.M. Idriss; Kenneth Campbell; Norman Abrahamson; Walter Silva

Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

PEER Report 2012/01

By: Sanaz Rezaeian, Yousef Bozorgnia, I.M. Idriss, Kenneth Campbell, Norman Abrahamson, and Walter Silva

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Abstract

Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

Additional publication details
Publication type	Report
Publication Subtype	Organization Series
Title	Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions
Series title	PEER Report
Series number	2012/01
Year Published	2012
Language	English
Publisher	Pacific Earthquake Engineering Research Center
Publisher location	Berkeley, CA
Contributing office(s)	Geologic Hazards Science Center
Description	xiv, 142 p.
Google Analytic Metrics	Metrics page