Documents disponibles écrits par cet auteur

Bench-shelf system dynamic characteristics and their effects on equipment and contents / Hutchinson, Tara C. in Earthquake engineering structural dynamics, Vol. 35 N° 13 (Novembre 2006) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 35 N° 13 (Novembre 2006) . - 1631 - 1651 p. Titre : Bench-shelf system dynamic characteristics and their effects on equipment and contents Type de document : texte imprimé Auteurs : Hutchinson, Tara C., Auteur ; Chaudhuri, Samit Ray, Auteur Article en page(s) : 1631 - 1651 p. Note générale : Génie civil Langues : Anglais (eng) Mots-clés : Shake  table  testing  Nonstructural  components  Dynamic  characterization  Furniture  response  Acceleration  amplification  Essai  de  table  de  secousse  Composants  nonstructural  Caractérisation  dynamique  Réponse  de  meubles  Amplification  d'accélération Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Economic losses during past earthquakes are strongly associated with damage and failure to nonstructural equipment and contents. Among the vast types of nonstructural elements, one important category, is scientific equipment in biological or chemical laboratories. These equipment are often mounted on heavy ceramic bench-tops of bench-shelf systems, which in turn may amplify the dynamic motions imposed. To investigate the seismic response of these types of systems, a series of shake table and field experiments were conducted considering different representative bench and shelf-mounted equipment and contents. Results from shake table experiments indicate that these equipment are generally sliding-dominated. In addition, the bench-shelf system is observed to be very stiff and when lightly loaded, has a fundamental frequency between 10 and 16 Hz. An approximate 50% reduction in the first and second fundamental frequencies is observed considering practical loading conditions. Insight into a broader range of system response is provided by conducting eigenvalue and time history analyses. Non-linear regression through the numerical data indicate acceleration amplification ratios range from 2.6 to 1.4 and from 4.3 to 1.6, for fixed-fixed and pinned-pinned conditions, respectively. Both the experimental and numerical results support the importance of determining the potential dynamic amplification of motion in the context of accurately determining the maximum sliding displacement of support equipment and contents. Des pertes économiques pendant des tremblements de terre passés sont fortement associées aux dommages et à l'échec à l'équipement et au contenu non structural. Parmi les vastes types d'éléments non structural, une catégorie importante, est équipement scientifique dans les laboratoires biologiques ou chimiques. Ces l'équipement sont souvent montés sur mettre hors jeu-tops en céramique lourd des systèmes de mettre hors jeu-shelf, qui alternativement peuvent amplifier les mouvements dynamiques imposés. Pour étudier la réponse séismique de ces types de systèmes, une série de table de secousse et des expériences sur le terrain ont été conduites considérant le représentant différent mettent hors jeu et étagère-ont monté l'équipement et le contenu. Les résultats des expériences de table de secousse indiquent que ces équipements glisser-sont généralement dominés. En outre, le système de mettre hors jeu-shelf est observé pour être très raide et une fois légèrement chargé, a une fréquence fondamentale entre 10 et 16 hertz. On observe une réduction approximative de 50% des premières et deuxièmes fréquences fondamentales considérer des conditions de charge pratiques. L'aperçu d'une plus large gamme de réaction de système est fourni en conduisant des analyses d'histoire de valeur propre et de temps. La régression non linéaire par les données numériques indiquent que des rapports d'amplification d'accélération s'étendent de 2.6 à 1.4 et de 4.3 à 1.6, parce que de conditions fixe-fixes et goupiller-goupillées, respectivement. Les résultats expérimentaux et numériques soutiennent l'importance de déterminer l'amplification dynamique potentiel du mouvement dans le contexte de déterminer exactement le déplacement coulissant de maximum de l'équipement et du contenu de soutien. ISSN : 0098-8847 RAMEAU : Secousse En ligne : http://www3.interscience.wiley.com/journal/117869386/issue [article] Bench-shelf system dynamic characteristics and their effects on equipment and contents [texte imprimé] / Hutchinson, Tara C., Auteur ; Chaudhuri, Samit Ray, Auteur . - 1631 - 1651 p. Génie civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 35 N° 13 (Novembre 2006) . - 1631 - 1651 p. Mots-clés : Shake  table  testing  Nonstructural  components  Dynamic  characterization  Furniture  response  Acceleration  amplification  Essai  de  table  de  secousse  Composants  nonstructural  Caractérisation  dynamique  Réponse  de  meubles  Amplification  d'accélération Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Economic losses during past earthquakes are strongly associated with damage and failure to nonstructural equipment and contents. Among the vast types of nonstructural elements, one important category, is scientific equipment in biological or chemical laboratories. These equipment are often mounted on heavy ceramic bench-tops of bench-shelf systems, which in turn may amplify the dynamic motions imposed. To investigate the seismic response of these types of systems, a series of shake table and field experiments were conducted considering different representative bench and shelf-mounted equipment and contents. Results from shake table experiments indicate that these equipment are generally sliding-dominated. In addition, the bench-shelf system is observed to be very stiff and when lightly loaded, has a fundamental frequency between 10 and 16 Hz. An approximate 50% reduction in the first and second fundamental frequencies is observed considering practical loading conditions. Insight into a broader range of system response is provided by conducting eigenvalue and time history analyses. Non-linear regression through the numerical data indicate acceleration amplification ratios range from 2.6 to 1.4 and from 4.3 to 1.6, for fixed-fixed and pinned-pinned conditions, respectively. Both the experimental and numerical results support the importance of determining the potential dynamic amplification of motion in the context of accurately determining the maximum sliding displacement of support equipment and contents. Des pertes économiques pendant des tremblements de terre passés sont fortement associées aux dommages et à l'échec à l'équipement et au contenu non structural. Parmi les vastes types d'éléments non structural, une catégorie importante, est équipement scientifique dans les laboratoires biologiques ou chimiques. Ces l'équipement sont souvent montés sur mettre hors jeu-tops en céramique lourd des systèmes de mettre hors jeu-shelf, qui alternativement peuvent amplifier les mouvements dynamiques imposés. Pour étudier la réponse séismique de ces types de systèmes, une série de table de secousse et des expériences sur le terrain ont été conduites considérant le représentant différent mettent hors jeu et étagère-ont monté l'équipement et le contenu. Les résultats des expériences de table de secousse indiquent que ces équipements glisser-sont généralement dominés. En outre, le système de mettre hors jeu-shelf est observé pour être très raide et une fois légèrement chargé, a une fréquence fondamentale entre 10 et 16 hertz. On observe une réduction approximative de 50% des premières et deuxièmes fréquences fondamentales considérer des conditions de charge pratiques. L'aperçu d'une plus large gamme de réaction de système est fourni en conduisant des analyses d'histoire de valeur propre et de temps. La régression non linéaire par les données numériques indiquent que des rapports d'amplification d'accélération s'étendent de 2.6 à 1.4 et de 4.3 à 1.6, parce que de conditions fixe-fixes et goupiller-goupillées, respectivement. Les résultats expérimentaux et numériques soutiennent l'importance de déterminer l'amplification dynamique potentiel du mouvement dans le contexte de déterminer exactement le déplacement coulissant de maximum de l'équipement et du contenu de soutien. ISSN : 0098-8847 RAMEAU : Secousse En ligne : http://www3.interscience.wiley.com/journal/117869386/issue

Experimental investigation of grouted helical piers for use in foundation rehabilitation / Yueying Bian in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1280-1289 Titre : Experimental investigation of grouted helical piers for use in foundation rehabilitation Type de document : texte imprimé Auteurs : Yueying Bian, Auteur ; Hutchinson, Tara C., Auteur ; Dan Wilson, Auteur Année de publication : 2008 Article en page(s) : pp. 1280-1289 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Grouting  Piers  Centrifuge  models  Rehabilitation  Deep  foundations Résumé : Building rehabilitation is critical for numerous older urban areas, many of which have inadequate foundations to support new demands. Consequently, development of practical methods to strengthen existing foundations is crucial. In engineering practice, both subsurface grouting and helical piers have been widely used to address these issues by strengthening the foundation. If the solid shaft of a typical helical pier is replaced by a hollow shaft, then helical piers provide the ability to deliver grout. It is hypothesized that these grouted helical pier systems could address foundation strengthening needs. This paper presents findings from an exploratory research program where grouting and pier placement tools were developed and tested on the large geotechnical centrifuge at the University of California, Davis. Experimental methods and procedures developed are presented, and observations regarding the formation of grout bulbs under different conditions are analyzed. Physical observation of the test specimens indicates that average grout bulb diameters of 0.6–1.9 times the helix diameter (Dh) are attainable. For similar grout mixes, 20–50% larger grout bulbs can be attained by adding just a modest amount of injection pressure. Future research may use these results to develop load performance data. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...] [article] Experimental investigation of grouted helical piers for use in foundation rehabilitation [texte imprimé] / Yueying Bian, Auteur ; Hutchinson, Tara C., Auteur ; Dan Wilson, Auteur . - 2008 . - pp. 1280-1289. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1280-1289 Mots-clés : Grouting  Piers  Centrifuge  models  Rehabilitation  Deep  foundations Résumé : Building rehabilitation is critical for numerous older urban areas, many of which have inadequate foundations to support new demands. Consequently, development of practical methods to strengthen existing foundations is crucial. In engineering practice, both subsurface grouting and helical piers have been widely used to address these issues by strengthening the foundation. If the solid shaft of a typical helical pier is replaced by a hollow shaft, then helical piers provide the ability to deliver grout. It is hypothesized that these grouted helical pier systems could address foundation strengthening needs. This paper presents findings from an exploratory research program where grouting and pier placement tools were developed and tested on the large geotechnical centrifuge at the University of California, Davis. Experimental methods and procedures developed are presented, and observations regarding the formation of grout bulbs under different conditions are analyzed. Physical observation of the test specimens indicates that average grout bulb diameters of 0.6–1.9 times the helix diameter (Dh) are attainable. For similar grout mixes, 20–50% larger grout bulbs can be attained by adding just a modest amount of injection pressure. Future research may use these results to develop load performance data. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...]

Performance evaluation of a nonlinear Winkler-based shallow foundation model using centrifuge test results / Prishati Raychowdhury in Earthquake engineering structural dynamics, Vol. 38 N°5 (Avril 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°5 (Avril 2009) . - pp. 679-698 Titre : Performance evaluation of a nonlinear Winkler-based shallow foundation model using centrifuge test results Type de document : texte imprimé Auteurs : Prishati Raychowdhury, Auteur ; Hutchinson, Tara C., Auteur Article en page(s) : pp. 679-698 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shallow  foundation;  Centrifuge  tests;  BNWF  modeling;  Nonlinear  analysis Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : When a structure supported on shallow foundations is subjected to inertial loading due to earthquake motions, the foundation may undergo sliding, settling and rocking movements. Even if the capacity of the foundation is mobilized, the soil-foundation interface may dissipate significant amounts of vibrational energy, resulting in reduced force demands to the superstructure. If the capacity is not mobilized, these movements introduce additional flexibility to the system, which may shift its period away from the potentially hazardous zone of response spectra for most earthquake ground motions. In either case, transient and permanent deformations will need to be accounted for. To consider the aforementioned benefits and consequences in performance-based seismic design, robust and reliable numerical modeling tools are needed. In this article, a Winkler-based modeling framework is proposed to address this issue. The model includes a distributed array of mechanistic nonlinear inelastic springs, dashpots, and gap elements, with backbone curves of the nonlinear springs calibrated against shallow foundation experiments. Model evaluation is conducted by simulating the response of a number of centrifuge experiments. Experiments considered include square and strip footings, bridge and building models, static and dynamic loading, footings on sand and clay, a range of static vertical factors of safety, and a range of aspect ratios. It is observed that the model can reasonably predict measured footing response in terms of moment, shear, settlement and rotational demands. In addition, the general hysteresis shape of the moment-rotation, settlement-rotation and shear-sliding curves is reasonably captured. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/122246967/abstract [article] Performance evaluation of a nonlinear Winkler-based shallow foundation model using centrifuge test results [texte imprimé] / Prishati Raychowdhury, Auteur ; Hutchinson, Tara C., Auteur . - pp. 679-698. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°5 (Avril 2009) . - pp. 679-698 Mots-clés : Shallow  foundation;  Centrifuge  tests;  BNWF  modeling;  Nonlinear  analysis Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : When a structure supported on shallow foundations is subjected to inertial loading due to earthquake motions, the foundation may undergo sliding, settling and rocking movements. Even if the capacity of the foundation is mobilized, the soil-foundation interface may dissipate significant amounts of vibrational energy, resulting in reduced force demands to the superstructure. If the capacity is not mobilized, these movements introduce additional flexibility to the system, which may shift its period away from the potentially hazardous zone of response spectra for most earthquake ground motions. In either case, transient and permanent deformations will need to be accounted for. To consider the aforementioned benefits and consequences in performance-based seismic design, robust and reliable numerical modeling tools are needed. In this article, a Winkler-based modeling framework is proposed to address this issue. The model includes a distributed array of mechanistic nonlinear inelastic springs, dashpots, and gap elements, with backbone curves of the nonlinear springs calibrated against shallow foundation experiments. Model evaluation is conducted by simulating the response of a number of centrifuge experiments. Experiments considered include square and strip footings, bridge and building models, static and dynamic loading, footings on sand and clay, a range of static vertical factors of safety, and a range of aspect ratios. It is observed that the model can reasonably predict measured footing response in terms of moment, shear, settlement and rotational demands. In addition, the general hysteresis shape of the moment-rotation, settlement-rotation and shear-sliding curves is reasonably captured. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/122246967/abstract

Sensitivity of shallow foundation response to model input parameters / Prishati Raychowdhury in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 538-541 Titre : Sensitivity of shallow foundation response to model input parameters Type de document : texte imprimé Auteurs : Prishati Raychowdhury, Auteur ; Hutchinson, Tara C., Auteur Article en page(s) : pp. 538-541 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Sensitivity  analysis  Shallow  foundations  Centrifuge  models  Model  verification Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : From a predictive point of view, it is desirable to characterize the effect of varying model input parameters on the seismic response of soil-foundation systems. In this paper, this issue is studied for shallow foundation systems in dry dense sand with varying vertical factors of safety, embedment depths, demand levels, and moment to shear ratios. Response parameters considered are the moment, shear, sliding, settlement, and rotation demands of the foundation. First-order sensitivity analyses indicate that among the soil input parameters, the friction angle has the most significant effect on capturing the foundation force and displacement demands. Furthermore, the uncertainty in friction angle contributes 80% of the variance of the settlement demand and 40% of the variance of the moment demand. It is also found that the uncertainty in Poisson's ratio has a marginal effect in predicting the studied foundation response. Although the findings of this study are limited to the parameter space considered herein and care should be taken for broader applicability, it does shed light on which parameters uncertainty should be minimized. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Sensitivity of shallow foundation response to model input parameters [texte imprimé] / Prishati Raychowdhury, Auteur ; Hutchinson, Tara C., Auteur . - pp. 538-541. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 538-541 Mots-clés : Sensitivity  analysis  Shallow  foundations  Centrifuge  models  Model  verification Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : From a predictive point of view, it is desirable to characterize the effect of varying model input parameters on the seismic response of soil-foundation systems. In this paper, this issue is studied for shallow foundation systems in dry dense sand with varying vertical factors of safety, embedment depths, demand levels, and moment to shear ratios. Response parameters considered are the moment, shear, sliding, settlement, and rotation demands of the foundation. First-order sensitivity analyses indicate that among the soil input parameters, the friction angle has the most significant effect on capturing the foundation force and displacement demands. Furthermore, the uncertainty in friction angle contributes 80% of the variance of the settlement demand and 40% of the variance of the moment demand. It is also found that the uncertainty in Poisson's ratio has a marginal effect in predicting the studied foundation response. Although the findings of this study are limited to the parameter space considered herein and care should be taken for broader applicability, it does shed light on which parameters uncertainty should be minimized. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]