Documents disponibles écrits par cet auteur

Accounting for ground-motion spectral shape characteristics in structural collapse assessment through an adjustment for epsilon / Curt B. Haselton in Journal of structural engineering, Vol. 137 N° 3 (Mars 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 332-344 Titre : Accounting for ground-motion spectral shape characteristics in structural collapse assessment through an adjustment for epsilon Type de document : texte imprimé Auteurs : Curt B. Haselton, Auteur ; Jack W. Baker, Auteur ; Abbie B. Liel, Auteur Année de publication : 2011 Article en page(s) : pp. 332-344 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ground  motions  Spectral  shape  Epsilon  Collapse  assessment  Performance  assessment  ATC-63  FEMA  P695 Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : One of the challenges of assessing structural collapse performance is the appropriate selection of ground motions for use in the nonlinear dynamic collapse simulation. The ground motions should represent characteristics of extreme ground motions that exceed the ground-motion intensities considered in the original building design. For modern buildings in the western United States, ground motions that cause collapse are expected to be rare high-intensity motions associated with a large magnitude earthquake. Recent research has shown that rare high-intensity ground motions have a peaked spectral shape that should be considered in ground-motion selection and scaling. One method to account for this spectral shape effect is through the selection of a set of ground motions that is specific to the building’s fundamental period and the site hazard characteristics. This selection presents a significant challenge when assessing the collapse capacity of a large number of buildings or for developing systematic procedures because it implies the need to assemble specific ground-motion sets for each building. This paper proposes an alternative method, whereby a general set of far-field ground motions is used for collapse simulation, and the resulting collapse capacity is adjusted to account for the spectral shape effects that are not reflected in the ground-motion selection. The simplified method is compared with the more direct record selection strategy, and results of the two approaches show good agreement. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p332_s1?isAuthorized=no [article] Accounting for ground-motion spectral shape characteristics in structural collapse assessment through an adjustment for epsilon [texte imprimé] / Curt B. Haselton, Auteur ; Jack W. Baker, Auteur ; Abbie B. Liel, Auteur . - 2011 . - pp. 332-344. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 332-344 Mots-clés : Ground  motions  Spectral  shape  Epsilon  Collapse  assessment  Performance  assessment  ATC-63  FEMA  P695 Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : One of the challenges of assessing structural collapse performance is the appropriate selection of ground motions for use in the nonlinear dynamic collapse simulation. The ground motions should represent characteristics of extreme ground motions that exceed the ground-motion intensities considered in the original building design. For modern buildings in the western United States, ground motions that cause collapse are expected to be rare high-intensity motions associated with a large magnitude earthquake. Recent research has shown that rare high-intensity ground motions have a peaked spectral shape that should be considered in ground-motion selection and scaling. One method to account for this spectral shape effect is through the selection of a set of ground motions that is specific to the building’s fundamental period and the site hazard characteristics. This selection presents a significant challenge when assessing the collapse capacity of a large number of buildings or for developing systematic procedures because it implies the need to assemble specific ground-motion sets for each building. This paper proposes an alternative method, whereby a general set of far-field ground motions is used for collapse simulation, and the resulting collapse capacity is adjusted to account for the spectral shape effects that are not reflected in the ground-motion selection. The simplified method is compared with the more direct record selection strategy, and results of the two approaches show good agreement. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p332_s1?isAuthorized=no

Conditional mean spectrum / Jack W. Baker in Journal of structural engineering, Vol. 137 N° 3 (Mars 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 322-331 Titre : Conditional mean spectrum : tool for ground-motion selection Type de document : texte imprimé Auteurs : Jack W. Baker, Auteur Année de publication : 2011 Article en page(s) : pp. 322-331 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ground  motions  Record  selection  Uniform  hazard  spectrum  Conditional  mean  spectrum  Epsilon Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A common goal of dynamic structural analysis is to predict the response of a structure subjected to ground motions having a specified spectral acceleration at a given period. This is important, for example, when coupling ground-motion hazard curves from probabilistic seismic hazard analysis (PSHA) with results from dynamic structural analysis. The prediction is often obtained by selecting ground motions that match a target response spectrum and using those ground motions as input to dynamic analysis. The commonly used uniform hazard spectrum (UHS) is shown here to be an unsuitable target for this purpose, as it conservatively implies that large-amplitude spectral values will occur at all periods within a single ground motion. An alternative, termed a conditional mean spectrum (CMS), is presented here. The CMS provides the expected (i.e., mean) response spectrum, conditioned on occurrence of a target spectral acceleration value at the period of interest. It is argued that this is the appropriate target response spectrum for the goal described above and is thus a useful tool for selecting ground motions as input to dynamic analysis. The CMS is described, its advantages relative to the UHS are explained, and practical guidelines for use in ground-motion selection are presented. Recent work illustrating the impact of this change in target spectrum on resulting structural response is briefly summarized. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p322_s1?isAuthorized=no [article] Conditional mean spectrum : tool for ground-motion selection [texte imprimé] / Jack W. Baker, Auteur . - 2011 . - pp. 322-331. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 322-331 Mots-clés : Ground  motions  Record  selection  Uniform  hazard  spectrum  Conditional  mean  spectrum  Epsilon Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A common goal of dynamic structural analysis is to predict the response of a structure subjected to ground motions having a specified spectral acceleration at a given period. This is important, for example, when coupling ground-motion hazard curves from probabilistic seismic hazard analysis (PSHA) with results from dynamic structural analysis. The prediction is often obtained by selecting ground motions that match a target response spectrum and using those ground motions as input to dynamic analysis. The commonly used uniform hazard spectrum (UHS) is shown here to be an unsuitable target for this purpose, as it conservatively implies that large-amplitude spectral values will occur at all periods within a single ground motion. An alternative, termed a conditional mean spectrum (CMS), is presented here. The CMS provides the expected (i.e., mean) response spectrum, conditioned on occurrence of a target spectral acceleration value at the period of interest. It is argued that this is the appropriate target response spectrum for the goal described above and is thus a useful tool for selecting ground motions as input to dynamic analysis. The CMS is described, its advantages relative to the UHS are explained, and practical guidelines for use in ground-motion selection are presented. Recent work illustrating the impact of this change in target spectrum on resulting structural response is briefly summarized. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p322_s1?isAuthorized=no

Correlation model for spatially distributed ground-motion intensities / Jayaram, Nirmal in Earthquake engineering structural dynamics, Vol. 38 N° 15 (Décembre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 15 (Décembre 2009) . - pp. 1687-1707 Titre : Correlation model for spatially distributed ground-motion intensities Type de document : texte imprimé Auteurs : Jayaram, Nirmal, Auteur ; Jack W. Baker, Auteur Article en page(s) : pp. 1687-1707 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Patial  correlation;  Spectral  accelerations;  Coherency;  Risk  assessement;  Infrastructure  systems Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Risk assessment of spatially distributed building portfolios or infrastructure systems requires quantification of the joint occurrence of ground-motion intensities at several sites, during the same earthquake. The ground-motion models that are used for site-specific hazard analysis do not provide information on the spatial correlation between ground-motion intensities, which is required for the joint prediction of intensities at multiple sites. Moreover, researchers who have previously computed these correlations using observed ground-motion recordings differ in their estimates of spatial correlation. In this paper, ground motions observed during seven past earthquakes are used to estimate correlations between spatially distributed spectral accelerations at various spectral periods. Geostatistical tools are used to quantify and express the observed correlations in a standard format. The estimated correlation model is also compared with previously published results, and apparent discrepancies among the previous results are explained. The analysis shows that the spatial correlation reduces with increasing separation between the sites of interest. The rate of decay of correlation typically decreases with increasing spectral acceleration period. At periods longer than 2 s, the correlations were similar for all the earthquake ground motions considered. At shorter periods, however, the correlations were found to be related to the local-site conditions (as indicated by site Vs30 values) at the ground-motion recording stations. The research work also investigates the assumption of isotropy used in developing the spatial correlation models. It is seen using the Northridge and Chi-Chi earthquake time histories that the isotropy assumption is reasonable at both long and short periods. Based on the factors identified as influencing the spatial correlation, a model is developed that can be used to select appropriate correlation estimates for use in practical risk assessment problems. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Correlation model for spatially distributed ground-motion intensities [texte imprimé] / Jayaram, Nirmal, Auteur ; Jack W. Baker, Auteur . - pp. 1687-1707. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 15 (Décembre 2009) . - pp. 1687-1707 Mots-clés : Patial  correlation;  Spectral  accelerations;  Coherency;  Risk  assessement;  Infrastructure  systems Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Risk assessment of spatially distributed building portfolios or infrastructure systems requires quantification of the joint occurrence of ground-motion intensities at several sites, during the same earthquake. The ground-motion models that are used for site-specific hazard analysis do not provide information on the spatial correlation between ground-motion intensities, which is required for the joint prediction of intensities at multiple sites. Moreover, researchers who have previously computed these correlations using observed ground-motion recordings differ in their estimates of spatial correlation. In this paper, ground motions observed during seven past earthquakes are used to estimate correlations between spatially distributed spectral accelerations at various spectral periods. Geostatistical tools are used to quantify and express the observed correlations in a standard format. The estimated correlation model is also compared with previously published results, and apparent discrepancies among the previous results are explained. The analysis shows that the spatial correlation reduces with increasing separation between the sites of interest. The rate of decay of correlation typically decreases with increasing spectral acceleration period. At periods longer than 2 s, the correlations were similar for all the earthquake ground motions considered. At shorter periods, however, the correlations were found to be related to the local-site conditions (as indicated by site Vs30 values) at the ground-motion recording stations. The research work also investigates the assumption of isotropy used in developing the spatial correlation models. It is seen using the Northridge and Chi-Chi earthquake time histories that the isotropy assumption is reasonable at both long and short periods. Based on the factors identified as influencing the spatial correlation, a model is developed that can be used to select appropriate correlation estimates for use in practical risk assessment problems. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

Correlation of response spectral values for multicomponent ground motions / Jack W. Baker in Bulletin of the seismological society of America, Vol. 96 N° 1 (Fevrier 2006) 

Public ISBD [article]  in Bulletin of the seismological society of America > Vol. 96 N° 1 (Fevrier 2006) . - 215-227 p. Titre : Correlation of response spectral values for multicomponent ground motions Titre original : Corrélation des valeurs spectrales de réponse pour des mouvements au sol à plusieurs composants Type de document : texte imprimé Auteurs : Jack W. Baker, Auteur ; Allin Cornell, C., Auteur Article en page(s) : 215-227 p. Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sol  composants  orthogonaux Index. décimale : 551.2 Résumé : Ground-motion prediction (attenuation) models predict the probability distributions of spectral acceleration values for a specified earthquake event. These models provide only marginal distributions, however; they do not specify correlations among spectral accelerations with differing periods or orientations. In this article a large number of strong ground motions are used to empirically estimate these correlations, and nonlinear regression is used to develop approximate analytical equations for their evaluation. Because the correlations apply to residuals from a ground- motion prediction, they are in principle dependent on the ground-motion prediction model used. The observed correlations do not vary significantly when the underlying model is changed, however, suggesting that the predictions are applicable regardless of the model chosen by the analyst. The analytical correlation predictions improve upon previous predictions of correlations at differing periods in a randomly oriented horizontal ground-motion component. For correlations within a vertical ground motion or across orthogonal components of a ground motion, these results are believed to be the first of their kind. The resulting correlation coefficient predictions are useful for a range of problems related to seismic hazard and the response of structures. Past uses of previous correlation predictions are described, and future applications of the new predictions are proposed. These applications will allow analysts to better understand the properties of single- and multicomponent earthquake ground motions. Les modèles au sol de prévision de mouvement (atténuation) prévoient les distributions de probabilité des valeurs spectrales d'accélération pour un événement indiqué de tremblement de terre. Ces modèles fournissent seulement des distributions marginales, cependant ; ils n'indiquent pas des corrélations parmi des accélérations spectrales avec des périodes ou des orientations différentes. En cet article un grand nombre de mouvements au sol forts sont employés pour estimer empiriquement ces corrélations, et la régression non-linéaire est employée pour développer des équations analytiques approximatives pour leur évaluation. Puisque les corrélations s'appliquent aux résiduels à partir d'une prévision au sol de mouvement, elles sont en principe le modèle dépendant du sol de prévision de mouvement utilisé. Les corrélations observées ne changent pas de manière significative quand le modèle fondamental est changé, cependant, suggérant que les prévisions soient applicables indépendamment du modèle choisi par l'analyste. Les prévisions analytiques de corrélation s'améliorent sur des prévisions précédentes des corrélations aux périodes différentes dans un composant au sol horizontal aléatoirement orienté de mouvement. Pour des corrélations dans un mouvement au sol vertical ou à travers les composants orthogonaux d'un mouvement au sol, on pense que ces résultats so nt les premiers de leur sorte. Les prévisions résultantes de coefficient de corrélation sont utiles pour une gamme des problèmes liés au risque séismique et à la réponse des structures. Après des utilisations de corrélation précédente des prévisions sont décrites, et de futures applications des nouvelles prévisions sont proposées. Ces applications permettront à des analystes de comprendre mieux les propriétés des mouvements au sol de tremblement de terre simple et à plusieurs composants. DEWEY : 551.2 ISSN : 0037-1106 En ligne : http://www.seismosoc.org [article] Correlation of response spectral values for multicomponent ground motions = Corrélation des valeurs spectrales de réponse pour des mouvements au sol à plusieurs composants [texte imprimé] / Jack W. Baker, Auteur ; Allin Cornell, C., Auteur . - 215-227 p. Génie Civil Langues : Anglais (eng) in Bulletin of the seismological society of America > Vol. 96 N° 1 (Fevrier 2006) . - 215-227 p. Mots-clés : Sol  composants  orthogonaux Index. décimale : 551.2 Résumé : Ground-motion prediction (attenuation) models predict the probability distributions of spectral acceleration values for a specified earthquake event. These models provide only marginal distributions, however; they do not specify correlations among spectral accelerations with differing periods or orientations. In this article a large number of strong ground motions are used to empirically estimate these correlations, and nonlinear regression is used to develop approximate analytical equations for their evaluation. Because the correlations apply to residuals from a ground- motion prediction, they are in principle dependent on the ground-motion prediction model used. The observed correlations do not vary significantly when the underlying model is changed, however, suggesting that the predictions are applicable regardless of the model chosen by the analyst. The analytical correlation predictions improve upon previous predictions of correlations at differing periods in a randomly oriented horizontal ground-motion component. For correlations within a vertical ground motion or across orthogonal components of a ground motion, these results are believed to be the first of their kind. The resulting correlation coefficient predictions are useful for a range of problems related to seismic hazard and the response of structures. Past uses of previous correlation predictions are described, and future applications of the new predictions are proposed. These applications will allow analysts to better understand the properties of single- and multicomponent earthquake ground motions. Les modèles au sol de prévision de mouvement (atténuation) prévoient les distributions de probabilité des valeurs spectrales d'accélération pour un événement indiqué de tremblement de terre. Ces modèles fournissent seulement des distributions marginales, cependant ; ils n'indiquent pas des corrélations parmi des accélérations spectrales avec des périodes ou des orientations différentes. En cet article un grand nombre de mouvements au sol forts sont employés pour estimer empiriquement ces corrélations, et la régression non-linéaire est employée pour développer des équations analytiques approximatives pour leur évaluation. Puisque les corrélations s'appliquent aux résiduels à partir d'une prévision au sol de mouvement, elles sont en principe le modèle dépendant du sol de prévision de mouvement utilisé. Les corrélations observées ne changent pas de manière significative quand le modèle fondamental est changé, cependant, suggérant que les prévisions soient applicables indépendamment du modèle choisi par l'analyste. Les prévisions analytiques de corrélation s'améliorent sur des prévisions précédentes des corrélations aux périodes différentes dans un composant au sol horizontal aléatoirement orienté de mouvement. Pour des corrélations dans un mouvement au sol vertical ou à travers les composants orthogonaux d'un mouvement au sol, on pense que ces résultats so nt les premiers de leur sorte. Les prévisions résultantes de coefficient de corrélation sont utiles pour une gamme des problèmes liés au risque séismique et à la réponse des structures. Après des utilisations de corrélation précédente des prévisions sont décrites, et de futures applications des nouvelles prévisions sont proposées. Ces applications permettront à des analystes de comprendre mieux les propriétés des mouvements au sol de tremblement de terre simple et à plusieurs composants. DEWEY : 551.2 ISSN : 0037-1106 En ligne : http://www.seismosoc.org

Liquefaction risk assessment using geostatistics to account for soil spatial variability / Jack W. Baker in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°1 (Janvier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°1 (Janvier 2008) . - pp. 14–23 Titre : Liquefaction risk assessment using geostatistics to account for soil spatial variability Type de document : texte imprimé Auteurs : Jack W. Baker, Auteur ; Michael H. Faber, Auteur Année de publication : 2008 Article en page(s) : pp. 14–23 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Liquefaction  Statistics  Earthquakes  Soil  properties Résumé : Liquefaction triggering assessments are often performed for individual locations, providing little information in regard to the expected spatial extent of liquefaction events. The present paper proposes a method to quantify the potential extent of liquefaction by accounting for spatial dependence of soil properties and potential future earthquake shaking. Random-field theory and geostatistics tools are used to model soil properties and earthquake shaking intensity; this approach facilitates incorporation of measurement results obtained at individual locations within the area of interest. An empirical liquefaction triggering criterion is then used to model liquefaction occurrence as a function of the random-field realizations. The framework components are briefly described and an example analysis is performed to illustrate the details of the approach. The area of liquefied soil under a building in Adapazari, Turkey, is considered in the example, conditional upon soil property measurements obtained from nearby standard penetration tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A1%2814 [...] [article] Liquefaction risk assessment using geostatistics to account for soil spatial variability [texte imprimé] / Jack W. Baker, Auteur ; Michael H. Faber, Auteur . - 2008 . - pp. 14–23. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°1 (Janvier 2008) . - pp. 14–23 Mots-clés : Liquefaction  Statistics  Earthquakes  Soil  properties Résumé : Liquefaction triggering assessments are often performed for individual locations, providing little information in regard to the expected spatial extent of liquefaction events. The present paper proposes a method to quantify the potential extent of liquefaction by accounting for spatial dependence of soil properties and potential future earthquake shaking. Random-field theory and geostatistics tools are used to model soil properties and earthquake shaking intensity; this approach facilitates incorporation of measurement results obtained at individual locations within the area of interest. An empirical liquefaction triggering criterion is then used to model liquefaction occurrence as a function of the random-field realizations. The framework components are briefly described and an example analysis is performed to illustrate the details of the approach. The area of liquefied soil under a building in Adapazari, Turkey, is considered in the example, conditional upon soil property measurements obtained from nearby standard penetration tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A1%2814 [...]

Probabilistic structural response assessment using vector-valued intensity measures / Jack W. Baker in Earthquake engineering structural dynamics, Vol. 36 N°13 (Novembre 2007) 

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Probabilistic structural response assessment using vector-valued intensity measures / Jack W. Baker in Earthquake engineering structural dynamics, Vol. 36 N°13 (Novembre 2007) 

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