Ground-motion models for average spectral acceleration in a period range: direct and indirect methods

• Published in: Bulletin of earthquake engineering Vol. 16; no. 1; pp. 45 - 65
• Main Authors: Kohrangi, Mohsen, Kotha, Sreeram Reddy, Bazzurro, Paolo
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.01.2018; Springer Nature B.V; Springer Verlag
• Subjects: Acceleration; Civil Engineering; Coefficients; Correlation coefficient; Correlation coefficients; Earth and Environmental Science; Earth Sciences; Engineering Sciences; Environmental Engineering/Biotechnology; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Ground motion; Hydrogeology; Methods; Original Research Paper; Predictions; Spectra; Structural Geology; Ground motion prediction equations; Intensity measure; Average spectral acceleration
• ISSN: 1570-761X; 1573-1456
• DOI: 10.1007/s10518-017-0216-5

Average spectral acceleration, AvgSA , is defined as the geometric mean of spectral acceleration values over a range of periods and it is a ground motion intensity measure used for structural response prediction. One of its advantages stands on the assumption that its distribution is computable from the available GMPEs for spectral acceleration, GMPE- SA , (called here indirect method) without the need for deriving new specific GMPEs for AvgSA , GMPE- AvgSA, (called here direct method). To what extent this assumption is valid, however, has never been verified. As such, we derived an empirical GMPE- AvgSA based on RESORCE ground motion dataset and we compared its predicted values with those from a GMPE- SA via the indirect approach. As expected, the results show that the indirect approach yields median AvgSA estimates that are identical to those of the direct approach. However, the estimates of AvgSA variance of the two methods are identical only if both the GMPE- SA and their empirical correlation coefficients among different SA ordinates are derived from the same record dataset.