Documents disponibles écrits par cet auteur

Three-dimensional behavior of a spherical self-centering precast prestressed pile isolator / Rosita Jünemann 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. 541-564 Titre : Three-dimensional behavior of a spherical self-centering precast prestressed pile isolator Type de document : texte imprimé Auteurs : Rosita Jünemann, Auteur ; Llera (de la), Juan C., Auteur ; Jaime Besa, Auteur ; José L. Almazán Article en page(s) : pp. 541-564 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Kinematic  isolators;  Prestressed  rod;  Seismic  isolation  ;  Structural  element;  Self-centering;  Rolling  constraints Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A 3D analytical formulation of a precast prestressed pile (PPP) seismic isolator with top and bottom spherical rolling kinematic constraints is proposed. The PPP isolator was initially conceived as a low-cost seismic isolation (and foundation) system for housing units of low-income people. Since these structures are usually located at sites with poor soil conditions, the PPP isolator also works as a foundation pile by connecting the superstructure with more competent soil layers. The non-holonomic nature of the rolling constraint is dealt with by a structural formulation. The proposed 3D formulation is validated by numerical results obtained from a previously proposed formulation for the 2D problem, and a contact finite element model in ANSYS (www.ansys.com). Other issues associated with the dynamic response of isolated structures with the PPP are also examined, such as expected response reductions, variation in the axial force of the central prestressed cable, and torsional response amplifications. Finally, guidelines to estimate the actual 3D response using 2D analysis results are investigated. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/122210039/abstract [article] Three-dimensional behavior of a spherical self-centering precast prestressed pile isolator [texte imprimé] / Rosita Jünemann, Auteur ; Llera (de la), Juan C., Auteur ; Jaime Besa, Auteur ; José L. Almazán . - pp. 541-564. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°5 (Avril 2009) . - pp. 541-564 Mots-clés : Kinematic  isolators;  Prestressed  rod;  Seismic  isolation  ;  Structural  element;  Self-centering;  Rolling  constraints Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A 3D analytical formulation of a precast prestressed pile (PPP) seismic isolator with top and bottom spherical rolling kinematic constraints is proposed. The PPP isolator was initially conceived as a low-cost seismic isolation (and foundation) system for housing units of low-income people. Since these structures are usually located at sites with poor soil conditions, the PPP isolator also works as a foundation pile by connecting the superstructure with more competent soil layers. The non-holonomic nature of the rolling constraint is dealt with by a structural formulation. The proposed 3D formulation is validated by numerical results obtained from a previously proposed formulation for the 2D problem, and a contact finite element model in ANSYS (www.ansys.com). Other issues associated with the dynamic response of isolated structures with the PPP are also examined, such as expected response reductions, variation in the axial force of the central prestressed cable, and torsional response amplifications. Finally, guidelines to estimate the actual 3D response using 2D analysis results are investigated. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/122210039/abstract

Torsional balance as new design criterion for asymmetric structures with energy dissipation devices / José L. Almazán in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1421-1440 Titre : Torsional balance as new design criterion for asymmetric structures with energy dissipation devices Type de document : texte imprimé Auteurs : José L. Almazán, Auteur ; Llera (de la), Juan C., Auteur Article en page(s) : pp. 1421-1440 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Torsional  balance;  Plan  asymmetry;  Lateral-torsional  correlation;  Earthquake  response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Lateral-torsional coupling in asymmetric-plan buildings leads to correlated translations and rotations of the building plan, which generate uneven distributions of deformation demand among resisting planes. The deformation demand of a resisting plane depends on the relative magnitude of the plan translation and rotation and on the correlation between the two signals. Thus, small rotations highly correlated with building translation may lead to significantly different deformations of the resisting planes at the building edges. Consequently, the use of supplemental dampers is intended not only to reduce the magnitude of the plan translation and rotation, but also the correlation between these motions. For the sake of simplicity, linear viscous dampers are used in this investigation, which properly located in plan lead to a minimum response of the geometric center, thus achieving the same mean-square value of the displacements at the building edges. Mathematically, this condition may be understood as creating zero correlation between the translations and rotation at the geometric center of the plan, which represents an uncoupling in the mean-square sense. Results show that the optimal damper location depends on the static eccentricity and frequency ratio of the bare structure, the total amount of supplemental damping considered, and the frequency content of the excitation. Through a final 6-story model example, the torsional balance concept is demonstrated to work on multistory buildings subjected to bidirectional ground motions. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Torsional balance as new design criterion for asymmetric structures with energy dissipation devices [texte imprimé] / José L. Almazán, Auteur ; Llera (de la), Juan C., Auteur . - pp. 1421-1440. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1421-1440 Mots-clés : Torsional  balance;  Plan  asymmetry;  Lateral-torsional  correlation;  Earthquake  response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Lateral-torsional coupling in asymmetric-plan buildings leads to correlated translations and rotations of the building plan, which generate uneven distributions of deformation demand among resisting planes. The deformation demand of a resisting plane depends on the relative magnitude of the plan translation and rotation and on the correlation between the two signals. Thus, small rotations highly correlated with building translation may lead to significantly different deformations of the resisting planes at the building edges. Consequently, the use of supplemental dampers is intended not only to reduce the magnitude of the plan translation and rotation, but also the correlation between these motions. For the sake of simplicity, linear viscous dampers are used in this investigation, which properly located in plan lead to a minimum response of the geometric center, thus achieving the same mean-square value of the displacements at the building edges. Mathematically, this condition may be understood as creating zero correlation between the translations and rotation at the geometric center of the plan, which represents an uncoupling in the mean-square sense. Results show that the optimal damper location depends on the static eccentricity and frequency ratio of the bare structure, the total amount of supplemental damping considered, and the frequency content of the excitation. Through a final 6-story model example, the torsional balance concept is demonstrated to work on multistory buildings subjected to bidirectional ground motions. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

Torsional balance of plan-asymmetric structures with frictional dampers: experimental results / Vial, Ignacio J. in Earthquake engineering structural dynamics, Vol. 35 N°15 (Decembre 2006) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 35 N°15 (Decembre 2006) . - 1875 - 1898 p. Titre : Torsional balance of plan-asymmetric structures with frictional dampers: experimental results Type de document : texte imprimé Auteurs : Vial, Ignacio J., Auteur ; Llera (de la), Juan C., Auteur ; Ceballos, Víctor, Auteur ; José L. Almazán, Auteur Article en page(s) : 1875 - 1898 p. Note générale : Génie civil Langues : Anglais (eng) Mots-clés : Torsional  balance  Plan-asymmetry  Frictional  dampers  Empirical  centre  of  balance  Response  reduction  factors  Équilibre  de  torsion  Plan-asymétrie  Amortisseurs  de  friction  Centre  empirique  de  l'équilibre  Facteurs  de  réduction  de  réponse Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This investigation deals with the measured seismic response of a six-storey asymmetric structural model with frictional dampers. Its main objective is to experimentally prove the concept of weak torsional balance for mass- and stiffness-eccentric model configurations. The goal is to control the torsional response of these asymmetric structures and to achieve, if possible, a weak form of torsional balance by placing the so-called empirical centre of balance (ECB) of the structure at equal distance from the edges of the building plan. The control of the dynamic response of asymmetric structures is investigated herein by using steel-teflon frictional dampers. As expected from theory, experimental results show that the mean-square and peak displacement demand at the flexible and stiff edges of the plan may be similar in magnitude if the dampers are optimally placed. Frictional dampers have proven equally effective in controlling lateral-torsional coupling of torsionally flexible as well as stiff structures. On the other hand, it is shown that impulsive ground motions require larger frictional capacities to achieve weak torsional balance. Cette recherche traite la réponse séismique mesurée d'un modèle structural asymétrique d'six-étages avec les amortisseurs de friction. Son objectif principal est de prouver expérimentalement le concept de l'équilibre de torsion faible pour des configurations modèles de masse- et rigidité-excentriques. Le but est de commander la réponse de torsion de ces structures asymétriques et de réaliser, si possible, une forme faible d'équilibre de torsion en plaçant le prétendu centre empirique de l'équilibre (BCE) de la structure à la distance égale des bords du plan de bâtiment. La commande de la réponse dynamique des structures asymétriques est étudiée ci-dessus en employant les amortisseurs de friction d'acier-teflon. Comme prévu de la théorie, les résultats expérimentaux prouvent que le déplacement de moyenne carrée et de crête exigent au flexible et les bords raides du plan peuvent être semblables dans la grandeur si les amortisseurs sont de façon optimale placés. Les amortisseurs de friction se sont montrés également à commander efficace l'accouplement latéral-de torsion de flexible aussi bien que les structures raides. D'autre part, on lui montre que les mouvements au sol impulsifs exigent de plus grandes capacités de friction de réaliser l'équilibre de torsion faible. ISSN : 0098-8847 RAMEAU : Torsion En ligne : http://www3.interscience.wiley.com/cgi-bin/abstract/112782639/ABSTRACT?CRETRY=1& [...] [article] Torsional balance of plan-asymmetric structures with frictional dampers: experimental results [texte imprimé] / Vial, Ignacio J., Auteur ; Llera (de la), Juan C., Auteur ; Ceballos, Víctor, Auteur ; José L. Almazán, Auteur . - 1875 - 1898 p. Génie civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 35 N°15 (Decembre 2006) . - 1875 - 1898 p. Mots-clés : Torsional  balance  Plan-asymmetry  Frictional  dampers  Empirical  centre  of  balance  Response  reduction  factors  Équilibre  de  torsion  Plan-asymétrie  Amortisseurs  de  friction  Centre  empirique  de  l'équilibre  Facteurs  de  réduction  de  réponse Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This investigation deals with the measured seismic response of a six-storey asymmetric structural model with frictional dampers. Its main objective is to experimentally prove the concept of weak torsional balance for mass- and stiffness-eccentric model configurations. The goal is to control the torsional response of these asymmetric structures and to achieve, if possible, a weak form of torsional balance by placing the so-called empirical centre of balance (ECB) of the structure at equal distance from the edges of the building plan. The control of the dynamic response of asymmetric structures is investigated herein by using steel-teflon frictional dampers. As expected from theory, experimental results show that the mean-square and peak displacement demand at the flexible and stiff edges of the plan may be similar in magnitude if the dampers are optimally placed. Frictional dampers have proven equally effective in controlling lateral-torsional coupling of torsionally flexible as well as stiff structures. On the other hand, it is shown that impulsive ground motions require larger frictional capacities to achieve weak torsional balance. Cette recherche traite la réponse séismique mesurée d'un modèle structural asymétrique d'six-étages avec les amortisseurs de friction. Son objectif principal est de prouver expérimentalement le concept de l'équilibre de torsion faible pour des configurations modèles de masse- et rigidité-excentriques. Le but est de commander la réponse de torsion de ces structures asymétriques et de réaliser, si possible, une forme faible d'équilibre de torsion en plaçant le prétendu centre empirique de l'équilibre (BCE) de la structure à la distance égale des bords du plan de bâtiment. La commande de la réponse dynamique des structures asymétriques est étudiée ci-dessus en employant les amortisseurs de friction d'acier-teflon. Comme prévu de la théorie, les résultats expérimentaux prouvent que le déplacement de moyenne carrée et de crête exigent au flexible et les bords raides du plan peuvent être semblables dans la grandeur si les amortisseurs sont de façon optimale placés. Les amortisseurs de friction se sont montrés également à commander efficace l'accouplement latéral-de torsion de flexible aussi bien que les structures raides. D'autre part, on lui montre que les mouvements au sol impulsifs exigent de plus grandes capacités de friction de réaliser l'équilibre de torsion faible. ISSN : 0098-8847 RAMEAU : Torsion En ligne : http://www3.interscience.wiley.com/cgi-bin/abstract/112782639/ABSTRACT?CRETRY=1& [...]