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Accession Number PB2013-101796
Title Spectral Damping Scaling Factors for Shallow Crustal Earthquakes in Active Tectonic Regions.
Publication Date Jul 2012
Media Count 168p
Personal Author I. M. Idriss K. Campbell N. Abrahamson S. Rezaeian W. Silva Y. Bozorgnia
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 NGAWest2 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.
Keywords Attenuation
Earth crust
Ground motion
Scaling factors

Source Agency US Geological Survey
University of California Earthquake Engineering Research Cent Berkeley
NTIS Subject Category 48F - Geology & Geophysics
Corporate Author Geological Survey, Golden, CO.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1302
Contract Number N/A

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