Documents disponibles écrits par cet auteur

Deterministic excitation forces for simulation and identification of nonlinear hysteretic SDOF systems / Jin-Song Pei in Journal of engineering mechanics, Vol. 134 N°1 (Janvier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°1 (Janvier 2008) . - pp.35–48. Titre : Deterministic excitation forces for simulation and identification of nonlinear hysteretic SDOF systems Type de document : texte imprimé Auteurs : Jin-Song Pei, Auteur ; Krisda Piyawat, Auteur Année de publication : 2008 Article en page(s) : pp.35–48. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Excitation  Simulation  Hysteresis  Stiffness  Degradation Résumé : This paper investigates how to design deterministic excitation forces in studying nonlinear single-degree-of-freedom systems, especially those with rate and path dependency and strength and stiffness degradation. One frequency-modulated periodic excitation and its amplitude-modulated counterpart are proposed as a solution, and a series of numerical exercises are carried out to show that these forces can be designed for sufficient forcing functions to study the complex nonlinear hysteresis. To rapidly reveal the underlying characteristics of the system and also to further lead to an effective system identification, four evaluation tools are proposed to be utilized together with the proposed excitation forces. These tools include the response curves, force-state map, intercycle drift, and intercycle pattern change, based on which some distinctive “patterns” are obtained to reveal the existence of nonlinearities, types of nonlinearities, existence of memory, and degradation. By using both Bouc-Wen and Bouc-Wen-Baber-Noori models for the system in all the simulations, the writers compare the commonly used forces with the proposed excitation forces to further demonstrate the advantages of the proposed excitation forces and evaluation tools. The writers also explore challenges in terms of implementing the proposed excitation forces. The results of this study are expected to benefit both physical testing and numerical simulation of complex nonlinear hysteretic systems in a time- and cost-effective manner, as well as leading to efficient schemes for system identification. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A1%2835 [...] [article] Deterministic excitation forces for simulation and identification of nonlinear hysteretic SDOF systems [texte imprimé] / Jin-Song Pei, Auteur ; Krisda Piyawat, Auteur . - 2008 . - pp.35–48. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°1 (Janvier 2008) . - pp.35–48. Mots-clés : Excitation  Simulation  Hysteresis  Stiffness  Degradation Résumé : This paper investigates how to design deterministic excitation forces in studying nonlinear single-degree-of-freedom systems, especially those with rate and path dependency and strength and stiffness degradation. One frequency-modulated periodic excitation and its amplitude-modulated counterpart are proposed as a solution, and a series of numerical exercises are carried out to show that these forces can be designed for sufficient forcing functions to study the complex nonlinear hysteresis. To rapidly reveal the underlying characteristics of the system and also to further lead to an effective system identification, four evaluation tools are proposed to be utilized together with the proposed excitation forces. These tools include the response curves, force-state map, intercycle drift, and intercycle pattern change, based on which some distinctive “patterns” are obtained to reveal the existence of nonlinearities, types of nonlinearities, existence of memory, and degradation. By using both Bouc-Wen and Bouc-Wen-Baber-Noori models for the system in all the simulations, the writers compare the commonly used forces with the proposed excitation forces to further demonstrate the advantages of the proposed excitation forces and evaluation tools. The writers also explore challenges in terms of implementing the proposed excitation forces. The results of this study are expected to benefit both physical testing and numerical simulation of complex nonlinear hysteretic systems in a time- and cost-effective manner, as well as leading to efficient schemes for system identification. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A1%2835 [...]

Linking Nonlinear System Identification with Nonlinear dynamic simulation under openSees / Krisda Piyawat in Journal of engineering mechanics, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 11 (Novembre 2009) . - pp. 1213-1226 Titre : Linking Nonlinear System Identification with Nonlinear dynamic simulation under openSees : some justifications and implementations Type de document : texte imprimé Auteurs : Krisda Piyawat, Auteur ; Pei, Jin-Song, Auteur Année de publication : 2009 Article en page(s) : pp. 1213-1226 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Nonlinear  systems  Simulation  Implementation  Experimentation. Résumé : This study seeks to bridge the gap between nonlinear system identification and nonlinear dynamic finite-element analysis. Motivated by the needs in earthquake simulation, it is first investigated under which conditions and to what degree the prediction of maximum lateral drift and base shear requires accurate nonlinear hysteretic moment-rotation joint models. A series of simulations is carried out using a simple but typical steel frame under two different earthquake ground motion time histories scaled up to various levels. As one of the two major classes of models in nonlinear system identification, nonparametric models are proposed to be implemented into OpenSees. A methodology with details is provided to effectively implement feedforward neural networks with one hidden layer as a new one-dimensional nonlinear smooth material model directly from a MATLAB environment to OpenSees. The same methodology can be applied to benefit the implementation of other parametric and nonparametric models with linear parameterization. Numerical examples are provided. Challenges are discussed and future work is identified. DEWEY : 620.1 RAMEAU : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&ONLINE=YES&s [...] [article] Linking Nonlinear System Identification with Nonlinear dynamic simulation under openSees : some justifications and implementations [texte imprimé] / Krisda Piyawat, Auteur ; Pei, Jin-Song, Auteur . - 2009 . - pp. 1213-1226. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 11 (Novembre 2009) . - pp. 1213-1226 Mots-clés : Nonlinear  systems  Simulation  Implementation  Experimentation. Résumé : This study seeks to bridge the gap between nonlinear system identification and nonlinear dynamic finite-element analysis. Motivated by the needs in earthquake simulation, it is first investigated under which conditions and to what degree the prediction of maximum lateral drift and base shear requires accurate nonlinear hysteretic moment-rotation joint models. A series of simulations is carried out using a simple but typical steel frame under two different earthquake ground motion time histories scaled up to various levels. As one of the two major classes of models in nonlinear system identification, nonparametric models are proposed to be implemented into OpenSees. A methodology with details is provided to effectively implement feedforward neural networks with one hidden layer as a new one-dimensional nonlinear smooth material model directly from a MATLAB environment to OpenSees. The same methodology can be applied to benefit the implementation of other parametric and nonparametric models with linear parameterization. Numerical examples are provided. Challenges are discussed and future work is identified. DEWEY : 620.1 RAMEAU : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&ONLINE=YES&s [...]