Comparison of Soil Nonlinearity (In SituStress–Strain Relation and G/Gmax Reduction) Observed in Strong‐Motion Databases and Modeled in Ground‐Motion Prediction Equations

Abstract

Research Article| November 20, 2018 Comparison of Soil Nonlinearity (In Situ Stress–Strain Relation and G/Gmax Reduction) Observed in Strong‐Motion Databases and Modeled in Ground‐Motion Prediction Equations Philippe Guéguen; Philippe Guéguen aISTerre, Université Grenoble Alpes, CNRS/IFSTTAR, 1381 rue de la piscine ‐ CS40700, 38058 Grenoble, Cedex 9, France, philippe.gueguen@univ-grenoble-alpes.fr Search for other works by this author on: GSW Google Scholar Luis Fabian Bonilla; Luis Fabian Bonilla bDépartement GERS (Géotechnique, Environnement, Risques naturels et Sciences de la terre), Laboratoire Séismes et Vibrations, Université Paris Est ‐ IFSTTAR, 14‐20 Boulevard Newton, Cité Descartes, 77447 Marne‐la‐Vallée, Cedex 2, France Search for other works by this author on: GSW Google Scholar John Douglas John Douglas cDepartment of Civil and Environmental Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2019) 109 (1): 178–186. https://doi.org/10.1785/0120180169 Article history first online: 20 Nov 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Philippe Guéguen, Luis Fabian Bonilla, John Douglas; Comparison of Soil Nonlinearity (In Situ Stress–Strain Relation and G/Gmax Reduction) Observed in Strong‐Motion Databases and Modeled in Ground‐Motion Prediction Equations. Bulletin of the Seismological Society of America 2018;; 109 (1): 178–186. doi: https://doi.org/10.1785/0120180169 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract Earthquake ground motions are strongly affected by the upper tens of meters of the Earth’s crust and consequently local site effects need to be included in any ground‐motion prediction. In ground‐motion prediction equations (GMPEs), it is increasingly common to account for possible nonlinear behavior of near‐surface materials (soil). These nonlinear site terms adjust observations made on soft soil sites to the ground motion expected on bedrock and hence allow these abundant soil records to be used within the regression analysis for the derivation of empirical GMPEs. These nonlinear site terms also allow rapid predictions of the expected ground motions on soil rather than requiring a site‐response analysis to be conducted. In this study, we compare the signature on observed peak ground acceleration as a function of a strain proxy of nonlinear soil behavior within four large strong‐motion databases to the predicted signature from four recent GMPEs, three of which explicitly include nonlinear site terms. We find that observed nonlinearity in the databases, interpreted in terms of strain–stress relationships and reduction of shear modulus, is limited, but even this limited effect is underestimated by the nonlinear site terms of the considered GMPEs, which suggests that predictions from these GMPEs could be biased for soft soil sites but also on bedrock. Some of this mismatch could be explained by the use of the average shear‐wave velocity in the top 30 m (⁠VS30⁠) to characterize sites as well as errors in these values. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.