Documents disponibles écrits par cet auteur

Dynamic response reduction of cantilevered columns by anchored constrained viscoelastic layer treatments / Genda Chen in Journal of engineering mechanics, Vol. 138 N° 1 (Janvier 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 1 (Janvier 2012) . - pp.12-21 Titre : Dynamic response reduction of cantilevered columns by anchored constrained viscoelastic layer treatments Type de document : texte imprimé Auteurs : Genda Chen, Auteur ; Wenjian Wang, Auteur ; Kazi R. Karim, Auteur Année de publication : 2012 Article en page(s) : pp.12-21 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Anchored  constraining  layer,  Constrained-layer  treatment,  Viscoelastic  layers  Structural  dynamics  Distributed  damping  Distributed  mass  system Résumé : This paper proposes a new constrained viscoelastic (VE) layer treatment as a distributed supplemental damping mechanism for structural members. A steady-state solution of a cantilevered column utilizing this system is formulated under harmonic loading and validated with experimental shake table tests. Parametric studies indicated that the new treatment can reduce the elastic response of a 1/5 -scale square column up to 20%, or increase the damping ratio of the column from 2% to 2.5%. They remain effective as the column begins rocking at the column-footing construction joint. The numerical results were found to be in general agreement with the shake table test data of two column specimens with and without VE layers. On the basis of the validated model, applying two VE layers of 2.38 mm-thick to cover the lower 50–90% height of a cantilevered column appears the most efficient, and can increase the damping ratio up to 12% for a full-scale column. The significant reduction in peak responses indicates that the proposed new constrained-layer system is promising for civil engineering applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000299 [article] Dynamic response reduction of cantilevered columns by anchored constrained viscoelastic layer treatments [texte imprimé] / Genda Chen, Auteur ; Wenjian Wang, Auteur ; Kazi R. Karim, Auteur . - 2012 . - pp.12-21. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 1 (Janvier 2012) . - pp.12-21 Mots-clés : Anchored  constraining  layer,  Constrained-layer  treatment,  Viscoelastic  layers  Structural  dynamics  Distributed  damping  Distributed  mass  system Résumé : This paper proposes a new constrained viscoelastic (VE) layer treatment as a distributed supplemental damping mechanism for structural members. A steady-state solution of a cantilevered column utilizing this system is formulated under harmonic loading and validated with experimental shake table tests. Parametric studies indicated that the new treatment can reduce the elastic response of a 1/5 -scale square column up to 20%, or increase the damping ratio of the column from 2% to 2.5%. They remain effective as the column begins rocking at the column-footing construction joint. The numerical results were found to be in general agreement with the shake table test data of two column specimens with and without VE layers. On the basis of the validated model, applying two VE layers of 2.38 mm-thick to cover the lower 50–90% height of a cantilevered column appears the most efficient, and can increase the damping ratio up to 12% for a full-scale column. The significant reduction in peak responses indicates that the proposed new constrained-layer system is promising for civil engineering applications. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000299

Recursive hilbert - huang transform method for time - varying property identification of linear shear - type buildings under base excitations / Zuocai Wang in Journal of engineering mechanics, Vol. 138 N° 6 (Juin 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.631-639 Titre : Recursive hilbert - huang transform method for time - varying property identification of linear shear - type buildings under base excitations Type de document : texte imprimé Auteurs : Zuocai Wang, Auteur ; Genda Chen, Auteur Année de publication : 2012 Article en page(s) : pp.631-639 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Hilbert-Huang  transform  System  identification  Stiffness  coefficient  Damping  coefficient  Time-varying  properties  Intrinsic  mode  function  orthogonality  High-voltage  switch  structure Résumé : This paper presents a recursive Hilbert-Huang transform method for the time-varying property identification of shear-type buildings under base excitations. To overcome nonorthogonality and modal perturbation issues, all significant intrinsic mode functions of each signal and their Hilbert transforms were summed to track any variation of structural parameters of a multistory building over time. Given floor masses, both the stiffness and damping coefficients of the building were identified one by one from the top to bottom story. The overall accuracy of the identified parameters was measured by an index of accuracy based on the weighted root-mean-squared evaluation proposed in this study. One- and two-story shear buildings with abruptly, gradually, and periodically varying parameters were used as examples. The numerical results indicated that the proposed method is efficient, robust, and accurate in tracking variations of the properties of multistory buildings. Finally, the proposed method was applied into the identification of the time-varying natural frequency of a real-world high-voltage switch structure due to the friction mechanism used in the switch. The range of the identified frequency by the proposed method was in good agreement with that attained by the conventional least-squares method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000357 [article] Recursive hilbert - huang transform method for time - varying property identification of linear shear - type buildings under base excitations [texte imprimé] / Zuocai Wang, Auteur ; Genda Chen, Auteur . - 2012 . - pp.631-639. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.631-639 Mots-clés : Hilbert-Huang  transform  System  identification  Stiffness  coefficient  Damping  coefficient  Time-varying  properties  Intrinsic  mode  function  orthogonality  High-voltage  switch  structure Résumé : This paper presents a recursive Hilbert-Huang transform method for the time-varying property identification of shear-type buildings under base excitations. To overcome nonorthogonality and modal perturbation issues, all significant intrinsic mode functions of each signal and their Hilbert transforms were summed to track any variation of structural parameters of a multistory building over time. Given floor masses, both the stiffness and damping coefficients of the building were identified one by one from the top to bottom story. The overall accuracy of the identified parameters was measured by an index of accuracy based on the weighted root-mean-squared evaluation proposed in this study. One- and two-story shear buildings with abruptly, gradually, and periodically varying parameters were used as examples. The numerical results indicated that the proposed method is efficient, robust, and accurate in tracking variations of the properties of multistory buildings. Finally, the proposed method was applied into the identification of the time-varying natural frequency of a real-world high-voltage switch structure due to the friction mechanism used in the switch. The range of the identified frequency by the proposed method was in good agreement with that attained by the conventional least-squares method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000357

Semiactive Control of the 20-Story Benchmark Building with Piezoelectric Friction Dampers / Genda Chen in Journal of engineering mechanics, Vol. 130 N°4 (Avril 2004) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 130 N°4 (Avril 2004) . - 393-400 p. Titre : Semiactive Control of the 20-Story Benchmark Building with Piezoelectric Friction Dampers Titre original : Commande de Semiactive du Bâtiment de Repère de 20 Etages avec les Amortisseurs de Frottement Piézoélectriques Type de document : texte imprimé Auteurs : Genda Chen, Auteur ; Chen, Chaoqiang, Auteur ; Spencer Jr., B. F., Editeur scientifique Article en page(s) : 393-400 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Friction  Damping  Piezoelectricity  Structural  control  Optimization  Performance  evaluation  Frottement  Atténuation  Piézoélectricité  Commande  structurale  Optimisation  Evaluation  des  performances Index. décimale : 621.34/624 Résumé : A New control algorithm is proposed in this paper to control the responses of a seismically excited, nonlinear 20-story building with piezoelectric friction dampers. The passive friction damping mechanism is used for low-amplitude vibration while the active counterpart takes over for high-amplitude vibration. Both the stick and sliding phases of dampers are taken into account. To effectively mitigate the peak story drift and floor acceleration of the 20-story building, multiple dampers are placed on the 20-story building based on a sequential procedure developed for optimal performance of the dampers. Extensive simulations indicate that the proposed semiactive dampers can effectively reduce the seismic responses of the uncontrolled building with substantially less external power than its associated active dampers, for instance, 67% less under the 1940 El Centro earthquake when the passive friction force is equal to 10% of the damper capacity. On Propose un nouvel algorithme de commande en cet article pour commander les réponses d'un bâtiment de 20 étages séismicalement passionnan'et non-linéaire avec les amortisseurs de frottement piézoélectriques. Le frottement passif atténuant le mécanisme est employé pour la vibration d'bas-amplitude tandis que les contre-parties actives succède pour la vibration d'haut-amplitude. Le bâton et des phases de glissement des amortisseurs sont pris en considération. Pour atténuer efficacement l'accélération maximale de dérive et de plancher d'histoire du bâtiment de 20 étages, des amortisseurs multiples sont placés sur le bâtiment de 20 étages basé sur un procédé séquentiel développé pour l'exécution optimale des amortisseurs. Les simulations étendues indiquent que les amortisseurs semiactive proposés peuvent efficacement réduire les réponses séismiques du bâtiment non contrôlé avec sensiblement moins de puissance externe que ses amortisseurs, par exemple, 67% actifs associés moins sous le tremblement de terre 1940 de EL Centro quand la force passive de frottement est égale à 10% de la capacité plus humide. En ligne : gchen@umr.edu [article] Semiactive Control of the 20-Story Benchmark Building with Piezoelectric Friction Dampers = Commande de Semiactive du Bâtiment de Repère de 20 Etages avec les Amortisseurs de Frottement Piézoélectriques [texte imprimé] / Genda Chen, Auteur ; Chen, Chaoqiang, Auteur ; Spencer Jr., B. F., Editeur scientifique . - 393-400 p. Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 130 N°4 (Avril 2004) . - 393-400 p. Mots-clés : Friction  Damping  Piezoelectricity  Structural  control  Optimization  Performance  evaluation  Frottement  Atténuation  Piézoélectricité  Commande  structurale  Optimisation  Evaluation  des  performances Index. décimale : 621.34/624 Résumé : A New control algorithm is proposed in this paper to control the responses of a seismically excited, nonlinear 20-story building with piezoelectric friction dampers. The passive friction damping mechanism is used for low-amplitude vibration while the active counterpart takes over for high-amplitude vibration. Both the stick and sliding phases of dampers are taken into account. To effectively mitigate the peak story drift and floor acceleration of the 20-story building, multiple dampers are placed on the 20-story building based on a sequential procedure developed for optimal performance of the dampers. Extensive simulations indicate that the proposed semiactive dampers can effectively reduce the seismic responses of the uncontrolled building with substantially less external power than its associated active dampers, for instance, 67% less under the 1940 El Centro earthquake when the passive friction force is equal to 10% of the damper capacity. On Propose un nouvel algorithme de commande en cet article pour commander les réponses d'un bâtiment de 20 étages séismicalement passionnan'et non-linéaire avec les amortisseurs de frottement piézoélectriques. Le frottement passif atténuant le mécanisme est employé pour la vibration d'bas-amplitude tandis que les contre-parties actives succède pour la vibration d'haut-amplitude. Le bâton et des phases de glissement des amortisseurs sont pris en considération. Pour atténuer efficacement l'accélération maximale de dérive et de plancher d'histoire du bâtiment de 20 étages, des amortisseurs multiples sont placés sur le bâtiment de 20 étages basé sur un procédé séquentiel développé pour l'exécution optimale des amortisseurs. Les simulations étendues indiquent que les amortisseurs semiactive proposés peuvent efficacement réduire les réponses séismiques du bâtiment non contrôlé avec sensiblement moins de puissance externe que ses amortisseurs, par exemple, 67% actifs associés moins sous le tremblement de terre 1940 de EL Centro quand la force passive de frottement est égale à 10% de la capacité plus humide. En ligne : gchen@umr.edu