Documents disponibles écrits par cet auteur

Amplitude-scaled versus spectrum-matched ground motions for seismic performance assessment / Yeong Ae Heo 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. 278-288 Titre : Amplitude-scaled versus spectrum-matched ground motions for seismic performance assessment Type de document : texte imprimé Auteurs : Yeong Ae Heo, Auteur ; Sashi K. Kunnath, Auteur ; Norman Abrahamson, Auteur Année de publication : 2011 Article en page(s) : pp. 278-288 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Interstory  drift  Ground  motion  modification  Probability  distribution  Reinforced  concrete  Seismic  simulation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The need to consider only a small number of ground motions combined with the complexities of response sensitivity to both modeling choices and ground motion variability calls for an assessment of current ground motion selection and modification methods used in seismic performance evaluation of structures. Since the largest source of uncertainty and variability arises from ground motion selection, this study examines the suitability of two ground motion modification (GMM) schemes: magnitude scaling (wherein the ground motion is uniformly scaled so that the resulting spectrum matches the amplitude of the design spectrum at the structural fundamental period) and spectrum matching. Comprehensive nonlinear time-history (NTH) simulations of two reinforced concrete moment frame buildings are carried out to evaluate the GMM approaches in the context of seismic demand prediction. Findings from the investigation indicate that spectrum matching is generally more stable than scaling both in terms of the bias as well as the resulting dispersion in the predicted demands. It is also concluded that seven ground motions are inadequate to establish median demands for taller frames where multiple modes influence structural response. Both methods are found to be sensitive to the choice of records for the cases investigated in this study. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p278_s1?isAuthorized=no [article] Amplitude-scaled versus spectrum-matched ground motions for seismic performance assessment [texte imprimé] / Yeong Ae Heo, Auteur ; Sashi K. Kunnath, Auteur ; Norman Abrahamson, Auteur . - 2011 . - pp. 278-288. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 278-288 Mots-clés : Interstory  drift  Ground  motion  modification  Probability  distribution  Reinforced  concrete  Seismic  simulation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The need to consider only a small number of ground motions combined with the complexities of response sensitivity to both modeling choices and ground motion variability calls for an assessment of current ground motion selection and modification methods used in seismic performance evaluation of structures. Since the largest source of uncertainty and variability arises from ground motion selection, this study examines the suitability of two ground motion modification (GMM) schemes: magnitude scaling (wherein the ground motion is uniformly scaled so that the resulting spectrum matches the amplitude of the design spectrum at the structural fundamental period) and spectrum matching. Comprehensive nonlinear time-history (NTH) simulations of two reinforced concrete moment frame buildings are carried out to evaluate the GMM approaches in the context of seismic demand prediction. Findings from the investigation indicate that spectrum matching is generally more stable than scaling both in terms of the bias as well as the resulting dispersion in the predicted demands. It is also concluded that seven ground motions are inadequate to establish median demands for taller frames where multiple modes influence structural response. Both methods are found to be sensitive to the choice of records for the cases investigated in this study. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i3/p278_s1?isAuthorized=no

Centrifuge modeling of bridge systems designed for rocking foundations / Lijun Deng in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 3 (Mars 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 335-344 Titre : Centrifuge modeling of bridge systems designed for rocking foundations Type de document : texte imprimé Auteurs : Lijun Deng, Auteur ; Kutter, Bruce L., Auteur ; Sashi K. Kunnath, Auteur Année de publication : 2012 Article en page(s) : pp. 335-344 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Earthquake  Shallow  foundation  Rocking  Bridge  Centrifuge  modeling Résumé : In good soil conditions, spread footings for bridges are less expensive than deep foundations. Furthermore, rocking shallow foundations have some performance advantages over conventional fixed-base foundations; they can absorb some of the ductility demand that would typically be absorbed by the columns, and they have better recentering characteristics than conventional reinforced-concrete (RC) columns. Foundations designed for elastic behavior do not have these benefits of nonlinear soil-structure interaction. One potential disadvantage of rocking systems is that they can produce significant settlement in poor soil conditions. Centrifuge model tests were performed to account for the interaction between soil, footing, column, deck and abutments systems. Bridge systems with rocking foundations on good soil conditions are shown to perform well and settlements are small. An improved method for quantification of settlements is presented. The model tests are described in some detail. One of the important factors limiting the use of rocking foundations is the perception that they might tip over; experiments show that tipping instability is unlikely if the foundations are properly sized. In one experiment, a column for a system with large fixed-base foundation collapsed while the systems with smaller rocking foundations did not collapse. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p335_s1?isAuthorized=no [article] Centrifuge modeling of bridge systems designed for rocking foundations [texte imprimé] / Lijun Deng, Auteur ; Kutter, Bruce L., Auteur ; Sashi K. Kunnath, Auteur . - 2012 . - pp. 335-344. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 335-344 Mots-clés : Earthquake  Shallow  foundation  Rocking  Bridge  Centrifuge  modeling Résumé : In good soil conditions, spread footings for bridges are less expensive than deep foundations. Furthermore, rocking shallow foundations have some performance advantages over conventional fixed-base foundations; they can absorb some of the ductility demand that would typically be absorbed by the columns, and they have better recentering characteristics than conventional reinforced-concrete (RC) columns. Foundations designed for elastic behavior do not have these benefits of nonlinear soil-structure interaction. One potential disadvantage of rocking systems is that they can produce significant settlement in poor soil conditions. Centrifuge model tests were performed to account for the interaction between soil, footing, column, deck and abutments systems. Bridge systems with rocking foundations on good soil conditions are shown to perform well and settlements are small. An improved method for quantification of settlements is presented. The model tests are described in some detail. One of the important factors limiting the use of rocking foundations is the perception that they might tip over; experiments show that tipping instability is unlikely if the foundations are properly sized. In one experiment, a column for a system with large fixed-base foundation collapsed while the systems with smaller rocking foundations did not collapse. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p335_s1?isAuthorized=no