Documents disponibles écrits par cet auteur

Application of the coupled local minimizers method to the optimization problem in the spectral analysis of surface waves method / Degrande, Geert in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°10 (Octobre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°10 (Octobre 2008) . - pp. 1541–1553 Titre : Application of the coupled local minimizers method to the optimization problem in the spectral analysis of surface waves method Type de document : texte imprimé Auteurs : Degrande, Geert, Auteur ; Sayed Ali Badsar, Auteur ; Geert Lombaert, Auteur Année de publication : 2008 Article en page(s) : pp. 1541–1553 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Shear  waves  Layered  soils  Optimization  Velocity  Half  space Résumé : The spectral analysis of surface waves (SASW) method aims to determine the small strain dynamic soil characteristics of shallow soil layers. The method involves an in situ experiment, the determination of an experimental dispersion curve, and the solution of an inverse problem, formulated as a nonlinear least squares problem. The latter is usually solved with a gradient-based local optimization method, which converges fast, but does not guarantee to find the global minimum of the objective function. The method of coupled local minimizers (CLM) combines the advantage of gradient-based local algorithms with the global approach of genetic algorithms. A cooperative search mechanism is set up by simultaneously performing a number of local optimization runs that are coupled by pairs of synchronization constraints. A synthetic example with two design variables (the shear wave velocity of two top layers of a layered half-space consisting of three layers on a half-space), demonstrates that the CLM method succeeds in finding the global minimum of an objective function with multiple minima and can successfully be used to solve the inverse problem in the SASW method. This is further illustrated by a complete inversion of the shear wave velocity profile accounting for seven design variables (the thickness and shear wave velocity of the three layers and the shear wave velocity of the underlying half-space). The inversion algorithm based on the CLM method is subsequently applied to invert the experimental dispersion curve derived from in situ data collected at a test site in Saluggia, Italy, consisting mainly of alluvial sediments. Up to a depth of about 25m , the results show a reasonably good correspondence with crosshole test results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A10%281 [...] [article] Application of the coupled local minimizers method to the optimization problem in the spectral analysis of surface waves method [texte imprimé] / Degrande, Geert, Auteur ; Sayed Ali Badsar, Auteur ; Geert Lombaert, Auteur . - 2008 . - pp. 1541–1553. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°10 (Octobre 2008) . - pp. 1541–1553 Mots-clés : Shear  waves  Layered  soils  Optimization  Velocity  Half  space Résumé : The spectral analysis of surface waves (SASW) method aims to determine the small strain dynamic soil characteristics of shallow soil layers. The method involves an in situ experiment, the determination of an experimental dispersion curve, and the solution of an inverse problem, formulated as a nonlinear least squares problem. The latter is usually solved with a gradient-based local optimization method, which converges fast, but does not guarantee to find the global minimum of the objective function. The method of coupled local minimizers (CLM) combines the advantage of gradient-based local algorithms with the global approach of genetic algorithms. A cooperative search mechanism is set up by simultaneously performing a number of local optimization runs that are coupled by pairs of synchronization constraints. A synthetic example with two design variables (the shear wave velocity of two top layers of a layered half-space consisting of three layers on a half-space), demonstrates that the CLM method succeeds in finding the global minimum of an objective function with multiple minima and can successfully be used to solve the inverse problem in the SASW method. This is further illustrated by a complete inversion of the shear wave velocity profile accounting for seven design variables (the thickness and shear wave velocity of the three layers and the shear wave velocity of the underlying half-space). The inversion algorithm based on the CLM method is subsequently applied to invert the experimental dispersion curve derived from in situ data collected at a test site in Saluggia, Italy, consisting mainly of alluvial sediments. Up to a depth of about 25m , the results show a reasonably good correspondence with crosshole test results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A10%281 [...]

Random vibration analysis of dynamic vehicle - bridge interaction due to road unevenness / Geert Lombaert in Journal of engineering mechanics, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.816–825. Titre : Random vibration analysis of dynamic vehicle - bridge interaction due to road unevenness Type de document : texte imprimé Auteurs : Geert Lombaert, Auteur ; Conte, Joel P., Auteur Année de publication : 2012 Article en page(s) : pp.816–825. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Vehicle-bridge  interaction  Road  surface  unevenness  Moving  load  Random  vibration Résumé : Vehicle-bridge interaction has been studied for a long time to investigate the structural behavior of bridges and vehicle ride comfort. An original frequency domain method is presented where the vehicle-bridge interaction problem is solved in a frame of reference that moves with the vehicle. The Fourier transform of the interaction force is computed directly from the vehicle compliance and bridge compliance, without requiring any iterations. The method is particularly useful when a closed-form solution of the bridge compliance is available, as in the case of a simply supported Euler-Bernoulli beam model for the bridge. The solution is, therefore, well-suited for parametric studies on the bridge and vehicle response characteristics and offers a reference for more detailed models of the bridge and the vehicle or more complicated bridge configurations (e.g., continuous beam on multiple supports). The frequency domain approach also leads to enhanced physical understanding, because it shows how the interaction force decomposes into a term resulting from the dynamic response of the bridge to the constant moving load component and a term because of road surface unevenness. An efficient solution procedure based on random vibration analysis is presented, which allows for the computing of the statistical characteristics of the bridge and vehicle response from the power spectral density function of the unevenness. The procedure is validated by means of Monte Carlo simulation results for the case where the passage of a heavy vehicle on a highway bridge is considered. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000386 [article] Random vibration analysis of dynamic vehicle - bridge interaction due to road unevenness [texte imprimé] / Geert Lombaert, Auteur ; Conte, Joel P., Auteur . - 2012 . - pp.816–825. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.816–825. Mots-clés : Vehicle-bridge  interaction  Road  surface  unevenness  Moving  load  Random  vibration Résumé : Vehicle-bridge interaction has been studied for a long time to investigate the structural behavior of bridges and vehicle ride comfort. An original frequency domain method is presented where the vehicle-bridge interaction problem is solved in a frame of reference that moves with the vehicle. The Fourier transform of the interaction force is computed directly from the vehicle compliance and bridge compliance, without requiring any iterations. The method is particularly useful when a closed-form solution of the bridge compliance is available, as in the case of a simply supported Euler-Bernoulli beam model for the bridge. The solution is, therefore, well-suited for parametric studies on the bridge and vehicle response characteristics and offers a reference for more detailed models of the bridge and the vehicle or more complicated bridge configurations (e.g., continuous beam on multiple supports). The frequency domain approach also leads to enhanced physical understanding, because it shows how the interaction force decomposes into a term resulting from the dynamic response of the bridge to the constant moving load component and a term because of road surface unevenness. An efficient solution procedure based on random vibration analysis is presented, which allows for the computing of the statistical characteristics of the bridge and vehicle response from the power spectral density function of the unevenness. The procedure is validated by means of Monte Carlo simulation results for the case where the passage of a heavy vehicle on a highway bridge is considered. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000386

Validation of a Source-Receiver Model for Road Traffic-Induced Vibrations in Buildings. I: Source Model / Pyl, Lincy in Journal of engineering mechanics, Vol. 130 N°12 (Decembre 2004)

Public ISBD [article]  in Journal of engineering mechanics > Vol. 130 N°12 (Decembre 2004) . - 1377-1393 p. Titre : Validation of a Source-Receiver Model for Road Traffic-Induced Vibrations in Buildings. I: Source Model Titre original : Validation d'un Modèle de Source-Récepteur pour des Vibrations Trafic-Induites par Route dans les Bâtiments. I : Modèle de Source Type de document : texte imprimé Auteurs : Pyl, Lincy, Auteur ; Ghanem, Roger G., Editeur scientifique ; Haegeman, Wim ; Geert Lombaert ; Degrande, Geert, Auteur Article en page(s) : 1377-1393 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Vibration  Buildings  Numerical  models  Vehicle  impacts  Traffic  Soil-structure  interaction  Bâtiments  Modèles  numériques  Impacts  de  véhicule  Trafic  Interaction  de  Sol-structure Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This work focuses on the coupling of a validated source model for free field traffic-induced vibrations to a receiver model that enables one to predict the response of buildings, accounting for dynamic soil–structure interaction. The resulting model is validated by means of in situ measurements, that have been performed in and around a single-family dwelling during the passage of a truck with known characteristics at speeds between 23 km/h and 58 km/h on joints between plates of the concrete pavement and on a plywood unevenness installed on the road. Simultaneous vibration measurements have been performed with a mobile data acquisition system on the truck’s axles. The objective of part I of this paper is to present the validation of the source model. The characteristics of the vehicle and the road unevenness are discussed, and the vehicle response is validated. The response is independent of the vehicle speed for the passage on the joints, whereas, for the passage on the plywood unevenness, the vibrations increase with the vehicle speed. The dynamic road.soil interaction problem is subsequently solved. Special consideration is given to the determination of the dynamic soil characteristics using the spectral analysis surface wave and seismic cone penetration test methods and to the validation of the transfer functions in the soil. The free-field incident wave field is finally validated. This incident wave field is used in part II of the paper to predict and validate the response of the single family dwelling. Ce travail se concentre sur l'accouplement d'un modèle validé de source pour des vibrations induites par trafic libre de champ à un modèle de récepteur qui permet de prévoir la réponse des bâtiments, expliquant l'interaction dynamique de structure de sol. Le modèle résultant est validé au moyen de mesures in situ, cela ont été exécutés dans et autour d'un logement unifamilial pendant le passage d'un camion avec des caractéristiques connues aux vitesses entre 23 km/h et 58 km/h sur des joints entre les plats du revêtement bétonné et sur une inégalité de contre-plaqué installée sur la route. Des mesures de vibration simultanées ont été effectuées avec un système d'acquisition de données mobile sur les axes du camion. L'objectif de la partie I de cet article est de présent la validation du modèle de source. Les caractéristiques du véhicule et de l'inégalité de route sont discutées, et la réponse de véhicule est validée. La réponse est indépendant de la vitesse de véhicule pour le passage sur les joints, tandis que, pour le passage sur l'inégalité de contre-plaqué, les vibrations augmentent avec la vitesse de véhicule. Le problème dynamique d'interaction de route-sol est plus tard résolu. L'attention spéciale à la détermination des caractéristiques dynamiques de sol en utilisant la vague de surface d'analyse spectrale et les méthodes séismiques d'essai de pénétration de cône et à la validation des fonctions de transfert dans le sol. Le champ libre de vague d'incident de champ est finalement validé. Ce champ de vague d'incident est employé dans la partie II du papier pour prévoir et valider la réponse du logement unifamilial. DEWEY : 620.1 ISSN : 0733-9399 [article] Validation of a Source-Receiver Model for Road Traffic-Induced Vibrations in Buildings. I: Source Model = Validation d'un Modèle de Source-Récepteur pour des Vibrations Trafic-Induites par Route dans les Bâtiments. I : Modèle de Source [texte imprimé] / Pyl, Lincy, Auteur ; Ghanem, Roger G., Editeur scientifique ; Haegeman, Wim ; Geert Lombaert ; Degrande, Geert, Auteur . - 1377-1393 p. Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 130 N°12 (Decembre 2004) . - 1377-1393 p. Mots-clés : Vibration  Buildings  Numerical  models  Vehicle  impacts  Traffic  Soil-structure  interaction  Bâtiments  Modèles  numériques  Impacts  de  véhicule  Trafic  Interaction  de  Sol-structure Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This work focuses on the coupling of a validated source model for free field traffic-induced vibrations to a receiver model that enables one to predict the response of buildings, accounting for dynamic soil–structure interaction. The resulting model is validated by means of in situ measurements, that have been performed in and around a single-family dwelling during the passage of a truck with known characteristics at speeds between 23 km/h and 58 km/h on joints between plates of the concrete pavement and on a plywood unevenness installed on the road. Simultaneous vibration measurements have been performed with a mobile data acquisition system on the truck’s axles. The objective of part I of this paper is to present the validation of the source model. The characteristics of the vehicle and the road unevenness are discussed, and the vehicle response is validated. The response is independent of the vehicle speed for the passage on the joints, whereas, for the passage on the plywood unevenness, the vibrations increase with the vehicle speed. The dynamic road.soil interaction problem is subsequently solved. Special consideration is given to the determination of the dynamic soil characteristics using the spectral analysis surface wave and seismic cone penetration test methods and to the validation of the transfer functions in the soil. The free-field incident wave field is finally validated. This incident wave field is used in part II of the paper to predict and validate the response of the single family dwelling. Ce travail se concentre sur l'accouplement d'un modèle validé de source pour des vibrations induites par trafic libre de champ à un modèle de récepteur qui permet de prévoir la réponse des bâtiments, expliquant l'interaction dynamique de structure de sol. Le modèle résultant est validé au moyen de mesures in situ, cela ont été exécutés dans et autour d'un logement unifamilial pendant le passage d'un camion avec des caractéristiques connues aux vitesses entre 23 km/h et 58 km/h sur des joints entre les plats du revêtement bétonné et sur une inégalité de contre-plaqué installée sur la route. Des mesures de vibration simultanées ont été effectuées avec un système d'acquisition de données mobile sur les axes du camion. L'objectif de la partie I de cet article est de présent la validation du modèle de source. Les caractéristiques du véhicule et de l'inégalité de route sont discutées, et la réponse de véhicule est validée. La réponse est indépendant de la vitesse de véhicule pour le passage sur les joints, tandis que, pour le passage sur l'inégalité de contre-plaqué, les vibrations augmentent avec la vitesse de véhicule. Le problème dynamique d'interaction de route-sol est plus tard résolu. L'attention spéciale à la détermination des caractéristiques dynamiques de sol en utilisant la vague de surface d'analyse spectrale et les méthodes séismiques d'essai de pénétration de cône et à la validation des fonctions de transfert dans le sol. Le champ libre de vague d'incident de champ est finalement validé. Ce champ de vague d'incident est employé dans la partie II du papier pour prévoir et valider la réponse du logement unifamilial. DEWEY : 620.1 ISSN : 0733-9399