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Détail de l'auteur
Auteur Richard J. Bathurst
Documents disponibles écrits par cet auteur
Affiner la rechercheLRFD calibration for steel strip reinforced soil walls / Bingquan Huang in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 8 (Août 2012)
in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 922–933
Titre : LRFD calibration for steel strip reinforced soil walls Type de document : texte imprimé Auteurs : Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Tony M. Allen, Auteur Année de publication : 2012 Article en page(s) : pp. 922–933 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Retaining walls Steel reinforcement Load and resistance factor design Reliability Pullout Yield Résumé : The paper reports the results of load and resistance factor design (LRFD) calibration for pullout and yield limit states for steel strip reinforced soil walls under self-weight loading. An important feature of the calibration method is the use of bias statistics to account for prediction accuracy of the underlying deterministic models for reinforcement load, pullout capacity and yield strength of the steel strips, and random variability in input parameters. To improve the accuracy of reinforcement load predictions, small adjustments to current semiempirical American Association of State Highway and Transportation Officials (AASHTO) load design charts are proposed. Similarly, current empirical-based design charts found in AASHTO and Federal Highway Administration (FHWA) guidance documents for the estimation of the pullout resistance factor for smooth and ribbed steel strips are adjusted to improve the accuracy of pullout capacity predictions. The results of calibration lead to a load factor of 1.35 that is consistent with current practice and resistance factors that together give a consistent probability of failure of 1% for all three limit states considered. Furthermore, comparison with allowable stress design (ASD) past practice (AASHTO simplified method) shows that the operational factors of safety using a rigorous LRFD approach give the same or higher factors of safety and lower probabilities of failure. In this study, data for steel strip reinforced soil walls are used as an example to illustrate rigorous reliability theory-based LRFD calibration concepts. However, the general approach is applicable to other reinforced soil wall technologies and calibration outcomes can be updated as more data become available. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000665 [article] LRFD calibration for steel strip reinforced soil walls [texte imprimé] / Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Tony M. Allen, Auteur . - 2012 . - pp. 922–933.
Géotechnique
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 922–933
Mots-clés : Retaining walls Steel reinforcement Load and resistance factor design Reliability Pullout Yield Résumé : The paper reports the results of load and resistance factor design (LRFD) calibration for pullout and yield limit states for steel strip reinforced soil walls under self-weight loading. An important feature of the calibration method is the use of bias statistics to account for prediction accuracy of the underlying deterministic models for reinforcement load, pullout capacity and yield strength of the steel strips, and random variability in input parameters. To improve the accuracy of reinforcement load predictions, small adjustments to current semiempirical American Association of State Highway and Transportation Officials (AASHTO) load design charts are proposed. Similarly, current empirical-based design charts found in AASHTO and Federal Highway Administration (FHWA) guidance documents for the estimation of the pullout resistance factor for smooth and ribbed steel strips are adjusted to improve the accuracy of pullout capacity predictions. The results of calibration lead to a load factor of 1.35 that is consistent with current practice and resistance factors that together give a consistent probability of failure of 1% for all three limit states considered. Furthermore, comparison with allowable stress design (ASD) past practice (AASHTO simplified method) shows that the operational factors of safety using a rigorous LRFD approach give the same or higher factors of safety and lower probabilities of failure. In this study, data for steel strip reinforced soil walls are used as an example to illustrate rigorous reliability theory-based LRFD calibration concepts. However, the general approach is applicable to other reinforced soil wall technologies and calibration outcomes can be updated as more data become available. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000665
in Canadian geotechnical journal > Vol. 46 N° 3 (Mars 2009) . - pp. 318–338
Titre : Numerical parametric study of expanded polystyrene (EPS) geofoam seismic buffers Type de document : texte imprimé Auteurs : Saman Zarnani, Auteur ; Richard J. Bathurst, Auteur Article en page(s) : pp. 318–338 Note générale : Sciences de la Terre Langues : Anglais (eng) Mots-clés : Geofoam Seismic buffer Rigid retaining wall Numerical analysis Parametric analysis Earthquake Géo mousse Tampon sismique Mur de soutènement rigide Analyse numérique Analyse paramétrique Tremblement de terre Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerograms and matching harmonic records with the same predominant frequency fall within a relatively narrow band when plotted against relative buffer thickness. For the range of parameters investigated, a buffer stiffness value less than 50 MN/m3 was judged to be the practical range for the design of these systems.
Des tampons sismiques faits de géo mousse de polystyrène expansé « EPS » peuvent être utilisés pour réduire les charges appliquées aux murs de soutènement rigides causées par les tremblements de terre. Une étude numérique a été effectuée pour investiguer l’influence de la hauteur du mur, du type de géo mousse « EPS », de l’épaisseur, de la rigidité, des données d’excitation sur le tampon sismique. Les simulations numériques ont été faites à l’aide d’un code FLAC vérifié. L’influence de la valeur des paramètres à été examinée en calculant les forces maximales sur les murs, la déformation en compression du tampon et l’efficacité relative du système de tampon. De façon générale, plus la fréquence prédominante d’excitation est près de la fréquence fondamentale du modèle de mur, plus élevés seront les charges sismiques et la compression du tampon. Le choix des données sismiques affecte la magnitude de la force maximale de la terre et l’efficacité d’isolation. Cependant, dans cette étude, lorsque les résultats pour des murs de 3 à 9 mètres de hauteur sont présentés en termes d’efficacité d’isolation, les données provenant des accélérogrammes et des données harmoniques correspondantes avec la même fréquence prédominante se retrouvent à l’intérieur d’une plage mince quand ils sont placés sur un graphique en fonction de l’épaisseur relative du tampon. Pour la gamme de paramètres évalués, une rigidité du tampon de moins de 50 MN/m3 est jugée comme un intervalle de valeurs approprié pour la conception de ces systèmes.
DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Numerical parametric study of expanded polystyrene (EPS) geofoam seismic buffers [texte imprimé] / Saman Zarnani, Auteur ; Richard J. Bathurst, Auteur . - pp. 318–338.
Sciences de la Terre
Langues : Anglais (eng)
in Canadian geotechnical journal > Vol. 46 N° 3 (Mars 2009) . - pp. 318–338
Mots-clés : Geofoam Seismic buffer Rigid retaining wall Numerical analysis Parametric analysis Earthquake Géo mousse Tampon sismique Mur de soutènement rigide Analyse numérique Analyse paramétrique Tremblement de terre Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerograms and matching harmonic records with the same predominant frequency fall within a relatively narrow band when plotted against relative buffer thickness. For the range of parameters investigated, a buffer stiffness value less than 50 MN/m3 was judged to be the practical range for the design of these systems.
Des tampons sismiques faits de géo mousse de polystyrène expansé « EPS » peuvent être utilisés pour réduire les charges appliquées aux murs de soutènement rigides causées par les tremblements de terre. Une étude numérique a été effectuée pour investiguer l’influence de la hauteur du mur, du type de géo mousse « EPS », de l’épaisseur, de la rigidité, des données d’excitation sur le tampon sismique. Les simulations numériques ont été faites à l’aide d’un code FLAC vérifié. L’influence de la valeur des paramètres à été examinée en calculant les forces maximales sur les murs, la déformation en compression du tampon et l’efficacité relative du système de tampon. De façon générale, plus la fréquence prédominante d’excitation est près de la fréquence fondamentale du modèle de mur, plus élevés seront les charges sismiques et la compression du tampon. Le choix des données sismiques affecte la magnitude de la force maximale de la terre et l’efficacité d’isolation. Cependant, dans cette étude, lorsque les résultats pour des murs de 3 à 9 mètres de hauteur sont présentés en termes d’efficacité d’isolation, les données provenant des accélérogrammes et des données harmoniques correspondantes avec la même fréquence prédominante se retrouvent à l’intérieur d’une plage mince quand ils sont placés sur un graphique en fonction de l’épaisseur relative du tampon. Pour la gamme de paramètres évalués, une rigidité du tampon de moins de 50 MN/m3 est jugée comme un intervalle de valeurs approprié pour la conception de ces systèmes.
DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1486–1498
Titre : Numerical study of reinforced soil segmental walls using three different constitutive soil models Type de document : texte imprimé Auteurs : Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Kianoosh Hatami, Auteur Année de publication : 2009 Article en page(s) : pp. 1486–1498 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil stabilizationWallsConstitutive modelsNumerical modelsReinforcement Résumé : A numerical finite-difference method (FLAC) model was used to investigate the influence of constitutive soil model on predicted response of two full-scale reinforced soil walls during construction and surcharge loading. One wall was reinforced with a relatively extensible polymeric geogrid and the other with a relatively stiff welded wire mesh. The backfill sand was modeled using three different constitutive soil models varying as follows with respect to increasing complexity: linear elastic-plastic Mohr-Coulomb, modified Duncan-Chang hyperbolic model, and Lade’s single hardening model. Calculated results were compared against toe footing loads, foundation pressures, facing displacements, connection loads, and reinforcement strains. In general, predictions were within measurement accuracy for the end-of-construction and surcharge load levels corresponding to working stress conditions. However, the modified Duncan-Chang model which explicitly considers plane strain boundary conditions is a good compromise between prediction accuracy and availability of parameters from conventional triaxial compression testing. The results of this investigation give confidence that numerical FLAC models using this simple soil constitutive model are adequate to predict the performance of reinforced soil walls under typical operational conditions provided that the soil reinforcement, interfaces, boundaries, construction sequence, and soil compaction are modeled correctly. Further improvement of predictions using more sophisticated soil models is not guaranteed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000092 [article] Numerical study of reinforced soil segmental walls using three different constitutive soil models [texte imprimé] / Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Kianoosh Hatami, Auteur . - 2009 . - pp. 1486–1498.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1486–1498
Mots-clés : Soil stabilizationWallsConstitutive modelsNumerical modelsReinforcement Résumé : A numerical finite-difference method (FLAC) model was used to investigate the influence of constitutive soil model on predicted response of two full-scale reinforced soil walls during construction and surcharge loading. One wall was reinforced with a relatively extensible polymeric geogrid and the other with a relatively stiff welded wire mesh. The backfill sand was modeled using three different constitutive soil models varying as follows with respect to increasing complexity: linear elastic-plastic Mohr-Coulomb, modified Duncan-Chang hyperbolic model, and Lade’s single hardening model. Calculated results were compared against toe footing loads, foundation pressures, facing displacements, connection loads, and reinforcement strains. In general, predictions were within measurement accuracy for the end-of-construction and surcharge load levels corresponding to working stress conditions. However, the modified Duncan-Chang model which explicitly considers plane strain boundary conditions is a good compromise between prediction accuracy and availability of parameters from conventional triaxial compression testing. The results of this investigation give confidence that numerical FLAC models using this simple soil constitutive model are adequate to predict the performance of reinforced soil walls under typical operational conditions provided that the soil reinforcement, interfaces, boundaries, construction sequence, and soil compaction are modeled correctly. Further improvement of predictions using more sophisticated soil models is not guaranteed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000092
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 177–184
Titre : Predicted loads in steel reinforced soil walls using the AASHTO simplified method Type de document : texte imprimé Auteurs : Richard J. Bathurst, Auteur ; Axel Nernheim, Auteur ; Tony M. Allen, Auteur Année de publication : 2009 Article en page(s) : pp. 177–184 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil stabilization Walls Steel Static loads Statistics Data analysis Résumé : The paper investigates the accuracy of the AASHTO simplified method by using load measurements reported in a large database of full-scale instrumented walls for bar mat, welded wire, and steel strip soil reinforced walls. The accuracy of the AASHTO simplified method is quantified by computing the mean and coefficient of variation of the ratio (bias) of measured loads under operational conditions to predicted loads. The paper shows that for steel strip walls, the AASHTO simplified method is reasonably accurate for granular backfill soils with friction angles less than 45°. For bar mat walls, the method is demonstrated to be slightly conservative. The simplified method underpredicts reinforcement loads at shallow overburden depths for steel strip walls with backfill friction angles greater than 45° due to compaction-related effects. It is concluded that these compaction-induced loads near the wall top do not contribute to internal instability due to pullout. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2817 [...] [article] Predicted loads in steel reinforced soil walls using the AASHTO simplified method [texte imprimé] / Richard J. Bathurst, Auteur ; Axel Nernheim, Auteur ; Tony M. Allen, Auteur . - 2009 . - pp. 177–184.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 177–184
Mots-clés : Soil stabilization Walls Steel Static loads Statistics Data analysis Résumé : The paper investigates the accuracy of the AASHTO simplified method by using load measurements reported in a large database of full-scale instrumented walls for bar mat, welded wire, and steel strip soil reinforced walls. The accuracy of the AASHTO simplified method is quantified by computing the mean and coefficient of variation of the ratio (bias) of measured loads under operational conditions to predicted loads. The paper shows that for steel strip walls, the AASHTO simplified method is reasonably accurate for granular backfill soils with friction angles less than 45°. For bar mat walls, the method is demonstrated to be slightly conservative. The simplified method underpredicts reinforcement loads at shallow overburden depths for steel strip walls with backfill friction angles greater than 45° due to compaction-related effects. It is concluded that these compaction-induced loads near the wall top do not contribute to internal instability due to pullout. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2817 [...]
