Documents disponibles écrits par cet auteur

Influence of spatially variable side friction and collocated data on single and multiple shaft resistances / Harald Klammler in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 84–94 Titre : Influence of spatially variable side friction and collocated data on single and multiple shaft resistances Type de document : texte imprimé Auteurs : Harald Klammler, Auteur ; Michael McVay, Auteur ; Peter Lai, Auteur Année de publication : 2013 Article en page(s) : pp. 84–94 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : load  and  resistance  factor  design;  shear  resistance;  spatial  analysis;  deep  foundations;  shafts;  data  analysis Résumé : Reliability-based design, such as LRFD, aims at meeting desired probability of failure levels for engineered structures. The present work attempts to contribute to this field by analyzing the influence of spatially variable soil/rock strength on the axial resistance uncertainty of single and multiple shafts in group layouts. This includes spatial variability over the individual shaft surfaces, effects of limited data, random measurement errors, and workmanship. A possible correlation between boring data inside or near the footprint of a foundation and the foundation itself is considered. In a geostatistical approach, spatial averaging (upscaling) and a degenerate case of ordinary kriging are applied to develop variance reduction charts and design equations for a series of foundation group layouts (single, double, triple, and quadruple). For the potential situation of an unknown horizontal correlation range at a site, the worst case scenarios are identified and demonstrated in an example problem. Resulting probabilities of failure are applied to the whole foundation (i.e., group) rather than single objects. It is found that a boring at the center of a group footprint can significantly reduce resistance prediction uncertainty, especially under the worst case scenario for unknown horizontal correlation range. In contrast, independent of the presence of a center boring or not, the uncertainty reduction through additional borings becomes small, once four or five borings are available. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000728 [article] Influence of spatially variable side friction and collocated data on single and multiple shaft resistances [texte imprimé] / Harald Klammler, Auteur ; Michael McVay, Auteur ; Peter Lai, Auteur . - 2013 . - pp. 84–94. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 84–94 Mots-clés : load  and  resistance  factor  design;  shear  resistance;  spatial  analysis;  deep  foundations;  shafts;  data  analysis Résumé : Reliability-based design, such as LRFD, aims at meeting desired probability of failure levels for engineered structures. The present work attempts to contribute to this field by analyzing the influence of spatially variable soil/rock strength on the axial resistance uncertainty of single and multiple shafts in group layouts. This includes spatial variability over the individual shaft surfaces, effects of limited data, random measurement errors, and workmanship. A possible correlation between boring data inside or near the footprint of a foundation and the foundation itself is considered. In a geostatistical approach, spatial averaging (upscaling) and a degenerate case of ordinary kriging are applied to develop variance reduction charts and design equations for a series of foundation group layouts (single, double, triple, and quadruple). For the potential situation of an unknown horizontal correlation range at a site, the worst case scenarios are identified and demonstrated in an example problem. Resulting probabilities of failure are applied to the whole foundation (i.e., group) rather than single objects. It is found that a boring at the center of a group footprint can significantly reduce resistance prediction uncertainty, especially under the worst case scenario for unknown horizontal correlation range. In contrast, independent of the presence of a center boring or not, the uncertainty reduction through additional borings becomes small, once four or five borings are available. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000728

Influence of spatially variable side friction on single drilled shaft resistance and LRFD resistance factors / Harald Klammler in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1114-1123 Titre : Influence of spatially variable side friction on single drilled shaft resistance and LRFD resistance factors Type de document : texte imprimé Auteurs : Harald Klammler, Auteur ; Michael McVay, Auteur ; David Horhota, Auteur Année de publication : 2010 Article en page(s) : pp. 1114-1123 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Load  resistance  factor  design  Failure  Reliability  Deep  foundation,  Geostatistics  Variogram  Variance  reduction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Load and resistance factor design (LRFD) is a method that aims at meeting specified target reliabilities (probabilities of failure) of engineered systems. The present work focuses on ultimate side friction resistance for axial loads on single cylindrical drilled shaft foundations in the presence of spatially variable rock/soil strength. Core sample data are assumed to provide reliable information about local strength in terms of mean, coefficient of variation and spatial correlation structure (variogram) at a site. The geostatistical principle of support up-scaling is applied to quantify the reduction in variability between local strength and the average ultimate shaft side friction resistance without having to recur to lengthy stochastic finite difference/element simulations. Site and shaft specific LRFD resistance factors (Φ values) are given based on the assumption of lognormal load and resistance distributions and existing formulas recommended by the Federal Highway Administration. Results are efficiently represented in dimensionless charts for a wide range of target reliabilities, shaft dimensions, and geostatistical parameters including nested variograms of different types with geometric and/or zonal anisotropies. Field data of local rock strength is used to demonstrate the method and to evaluate the sensitivity of obtained resistance factors to potentially uncertain variogram parameters. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1114_s1?isAuthorized=no [article] Influence of spatially variable side friction on single drilled shaft resistance and LRFD resistance factors [texte imprimé] / Harald Klammler, Auteur ; Michael McVay, Auteur ; David Horhota, Auteur . - 2010 . - pp. 1114-1123. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1114-1123 Mots-clés : Load  resistance  factor  design  Failure  Reliability  Deep  foundation,  Geostatistics  Variogram  Variance  reduction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Load and resistance factor design (LRFD) is a method that aims at meeting specified target reliabilities (probabilities of failure) of engineered systems. The present work focuses on ultimate side friction resistance for axial loads on single cylindrical drilled shaft foundations in the presence of spatially variable rock/soil strength. Core sample data are assumed to provide reliable information about local strength in terms of mean, coefficient of variation and spatial correlation structure (variogram) at a site. The geostatistical principle of support up-scaling is applied to quantify the reduction in variability between local strength and the average ultimate shaft side friction resistance without having to recur to lengthy stochastic finite difference/element simulations. Site and shaft specific LRFD resistance factors (Φ values) are given based on the assumption of lognormal load and resistance distributions and existing formulas recommended by the Federal Highway Administration. Results are efficiently represented in dimensionless charts for a wide range of target reliabilities, shaft dimensions, and geostatistical parameters including nested variograms of different types with geometric and/or zonal anisotropies. Field data of local rock strength is used to demonstrate the method and to evaluate the sensitivity of obtained resistance factors to potentially uncertain variogram parameters. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1114_s1?isAuthorized=no