Documents disponibles écrits par cet auteur

Full operator algorithm for hybrid simulation / Chung-Chan Hung in Earthquake engineering structural dynamics, Vol. 38 N° 13 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 13 (Octobre 2009) . - pp. 1545-1561 Titre : Full operator algorithm for hybrid simulation Type de document : texte imprimé Auteurs : Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur Article en page(s) : pp. 1545-1561 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Corrector  step;  Nonlinear  model;  Dynamics;  OpenSees;  Error  control Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : One of the weaknesses of the operator splitting method (OSM) is that its corrector step employs the approximation that incremental forces are linearly related to the tested structure's initial stiffness matrix. This paper presents a new predictor-corrector technique in which the assumptions about the tested structure's response are shifted to the predictor step, which results in an enhancement in overall simulation accuracy, especially for nonlinear structures. Unlike OSM, which splits the displacement and velocity operators into explicit and implicit terms, the new method uses predicted accelerations to compute fully explicit displacement and velocity values in the predictor step. Another advantage of the proposed technique, termed the full operator method (FOM) is that its formulation makes it suitable for both quasi-static and real-time hybrid simulation. The effectiveness of FOM is first evaluated by investigating error propagation in an undamped single degree-of-freedom model. It is shown that the corrector step in FOM is able to significantly suppress aberrant simulation results caused by incorrect estimation of the structure's stiffness matrix. The performance of FOM is demonstrated by exercising two additional models, which exhibit significant inelastic behavior under the prescribed excitation. The simulation results show that the proposed FOM algorithm is capable of producing accurate solutions and that the corrector step is influential in effectively reducing simulation errors. It is also shown that FOM suppresses actuator displacement control errors because of its reliance on measured quantities in the corrector step. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Full operator algorithm for hybrid simulation [texte imprimé] / Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur . - pp. 1545-1561. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 13 (Octobre 2009) . - pp. 1545-1561 Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Corrector  step;  Nonlinear  model;  Dynamics;  OpenSees;  Error  control Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : One of the weaknesses of the operator splitting method (OSM) is that its corrector step employs the approximation that incremental forces are linearly related to the tested structure's initial stiffness matrix. This paper presents a new predictor-corrector technique in which the assumptions about the tested structure's response are shifted to the predictor step, which results in an enhancement in overall simulation accuracy, especially for nonlinear structures. Unlike OSM, which splits the displacement and velocity operators into explicit and implicit terms, the new method uses predicted accelerations to compute fully explicit displacement and velocity values in the predictor step. Another advantage of the proposed technique, termed the full operator method (FOM) is that its formulation makes it suitable for both quasi-static and real-time hybrid simulation. The effectiveness of FOM is first evaluated by investigating error propagation in an undamped single degree-of-freedom model. It is shown that the corrector step in FOM is able to significantly suppress aberrant simulation results caused by incorrect estimation of the structure's stiffness matrix. The performance of FOM is demonstrated by exercising two additional models, which exhibit significant inelastic behavior under the prescribed excitation. The simulation results show that the proposed FOM algorithm is capable of producing accurate solutions and that the corrector step is influential in effectively reducing simulation errors. It is also shown that FOM suppresses actuator displacement control errors because of its reliance on measured quantities in the corrector step. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

A method for estimating specimen tangent stiffness for hybrid simulation / Chung-Chan Hung in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 115-134 Titre : A method for estimating specimen tangent stiffness for hybrid simulation Type de document : texte imprimé Auteurs : Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur Article en page(s) : pp. 115-134 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Implicit  methods  ;  Operator-splitting  method;  Accuracy;  Stability Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness matrix of a test specimen in hybrid simulations employing implicit and mixed-integration schemes. However, the computation of the tangent stiffness matrix during testing has proved to be challenging, particularly for test specimens with more than one degree of freedom (dof). This paper presents a new methodology that is more straightforward and simpler than existing techniques for computing the tangent stiffness matrix of a multi-dof test specimen. The proposed method is combined with the operator-splitting method (OSM), and the capabilities, advantages and limitations of the new formulation are demonstrated through several examples. The accuracy, stability, and error propagation characteristics of the modified OSM are also studied theoretically as well as numerically. The research results show that the proposed algorithm provides results that are better than those produced via the regular OSM alone, especially for damped structures undergoing highly inelastic behavior during testing. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121397333/abstract [article] A method for estimating specimen tangent stiffness for hybrid simulation [texte imprimé] / Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur . - pp. 115-134. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 115-134 Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Implicit  methods  ;  Operator-splitting  method;  Accuracy;  Stability Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness matrix of a test specimen in hybrid simulations employing implicit and mixed-integration schemes. However, the computation of the tangent stiffness matrix during testing has proved to be challenging, particularly for test specimens with more than one degree of freedom (dof). This paper presents a new methodology that is more straightforward and simpler than existing techniques for computing the tangent stiffness matrix of a multi-dof test specimen. The proposed method is combined with the operator-splitting method (OSM), and the capabilities, advantages and limitations of the new formulation are demonstrated through several examples. The accuracy, stability, and error propagation characteristics of the modified OSM are also studied theoretically as well as numerically. The research results show that the proposed algorithm provides results that are better than those produced via the regular OSM alone, especially for damped structures undergoing highly inelastic behavior during testing. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121397333/abstract

Seismic behavior of a coupled wall system with HPFRC materials in critical regions / Chung-Chan Hung in Journal of structural engineering, Vol. 137 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1499-1507 Titre : Seismic behavior of a coupled wall system with HPFRC materials in critical regions Type de document : texte imprimé Auteurs : Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur Année de publication : 2012 Article en page(s) : pp. 1499-1507 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Coupled  walls  Fiber-reinforced  materials  High-performance  fiber-reinforced  concrete  Concrete  structures  Earthquake-resistant  structures  Earthquake  engineering Résumé : High-performance fiber-reinforced concrete (HPFRC) materials have a unique strain-hardening behavior in tension that translates into enhanced structural response, especially under reversed cyclic loading. Recent experimental research has shown that the use of HPFRC to replace regular concrete in components subjected to high cyclic deformation demands can lead to significant benefits, such as relaxation of detailing requirements and reduction in the amount of reinforcing steel. A structural system that is a good candidate to benefit from HPFRC is reinforced concrete coupled walls, where coupling beams and plastic hinge zones undergo large cyclic deformation demands during the design seismic event. This paper discusses the seismic performance of a prototype 18-story coupled-wall system in which the wall plastic hinge zones and the coupling beams are made of HPFRC materials instead of regular reinforced concrete. Computational simulation models are used to investigate system performance under various hazard levels, and system response is evaluated through various parameters including interstory drift, rotation, and distortion of critical structural parts. The simulation results show that the use of HPFRC in place of regular concrete leads to good overall seismic response with enhanced plastic hinging behavior in the wall piers and crack control in the coupling beams and piers. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i12/p1499_s1?isAuthorized=no [article] Seismic behavior of a coupled wall system with HPFRC materials in critical regions [texte imprimé] / Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur . - 2012 . - pp. 1499-1507. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1499-1507 Mots-clés : Coupled  walls  Fiber-reinforced  materials  High-performance  fiber-reinforced  concrete  Concrete  structures  Earthquake-resistant  structures  Earthquake  engineering Résumé : High-performance fiber-reinforced concrete (HPFRC) materials have a unique strain-hardening behavior in tension that translates into enhanced structural response, especially under reversed cyclic loading. Recent experimental research has shown that the use of HPFRC to replace regular concrete in components subjected to high cyclic deformation demands can lead to significant benefits, such as relaxation of detailing requirements and reduction in the amount of reinforcing steel. A structural system that is a good candidate to benefit from HPFRC is reinforced concrete coupled walls, where coupling beams and plastic hinge zones undergo large cyclic deformation demands during the design seismic event. This paper discusses the seismic performance of a prototype 18-story coupled-wall system in which the wall plastic hinge zones and the coupling beams are made of HPFRC materials instead of regular reinforced concrete. Computational simulation models are used to investigate system performance under various hazard levels, and system response is evaluated through various parameters including interstory drift, rotation, and distortion of critical structural parts. The simulation results show that the use of HPFRC in place of regular concrete leads to good overall seismic response with enhanced plastic hinging behavior in the wall piers and crack control in the coupling beams and piers. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i12/p1499_s1?isAuthorized=no