Documents disponibles écrits par cet auteur

Design of passive systems for control of inelastic structures / Gian Paolo Cimellaro in Earthquake engineering structural dynamics, Vol. 38 N° 6 (Mai 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 6 (Mai 2009) . - pp. 783-804 Titre : Design of passive systems for control of inelastic structures Type de document : texte imprimé Auteurs : Gian Paolo Cimellaro, Auteur ; Oren Lavan, Auteur ; Reinhorn, Andrei M., Auteur Article en page(s) : pp. 783-804 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : passive  control;  design;  inelastic  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A design strategy for control of buildings experiencing inelastic deformations during seismic response is formulated. The strategy is using weakened, and/or softened, elements in a structural system while adding passive energy dissipation devices (e.g. viscous fluid devices, etc.) in order to control simultaneously accelerations and deformations response during seismic events. A design methodology is developed to determine the locations and the magnitude of weakening and/or softening of structural elements and the added damping while insuring structural stability. A two-stage design procedure is suggested: (i) first using a nonlinear active control algorithm, to determine the new structural parameters while insuring stability, then (ii) determine the properties of equivalent structural parameters of passive system, which can be implemented by removing or weakening some structural elements, or connections, and by addition of energy dissipation systems. Passive dampers and weakened elements are designed using an optimization algorithm to obtain a response as close as possible to an actively controlled system. A case study of a five-story building subjected to El Centro ground motion, as well as to an ensemble of simulated ground motions, is presented to illustrate the procedure. The results show that following the design strategy, a control of both peak inter-story drifts and total accelerations can be obtained. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121502892/abstract [article] Design of passive systems for control of inelastic structures [texte imprimé] / Gian Paolo Cimellaro, Auteur ; Oren Lavan, Auteur ; Reinhorn, Andrei M., Auteur . - pp. 783-804. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 6 (Mai 2009) . - pp. 783-804 Mots-clés : passive  control;  design;  inelastic  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A design strategy for control of buildings experiencing inelastic deformations during seismic response is formulated. The strategy is using weakened, and/or softened, elements in a structural system while adding passive energy dissipation devices (e.g. viscous fluid devices, etc.) in order to control simultaneously accelerations and deformations response during seismic events. A design methodology is developed to determine the locations and the magnitude of weakening and/or softening of structural elements and the added damping while insuring structural stability. A two-stage design procedure is suggested: (i) first using a nonlinear active control algorithm, to determine the new structural parameters while insuring stability, then (ii) determine the properties of equivalent structural parameters of passive system, which can be implemented by removing or weakening some structural elements, or connections, and by addition of energy dissipation systems. Passive dampers and weakened elements are designed using an optimization algorithm to obtain a response as close as possible to an actively controlled system. A case study of a five-story building subjected to El Centro ground motion, as well as to an ensemble of simulated ground motions, is presented to illustrate the procedure. The results show that following the design strategy, a control of both peak inter-story drifts and total accelerations can be obtained. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121502892/abstract

Dynamic analysis of gap closing and contact in the mixed lagrangian framework: toward progressive collapse prediction / Oren Lavan in Journal of engineering mechanics, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 136 N° 8 (Août 2010) . - pp. 979-986 Titre : Dynamic analysis of gap closing and contact in the mixed lagrangian framework: toward progressive collapse prediction Type de document : texte imprimé Auteurs : Oren Lavan, Auteur Article en page(s) : pp. 979-986 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Progressive  collapse  Contact  Dynamic  analysis  Predictions Résumé : Previous research has shown many advantages of the mixed Lagrangian formulation (MLF) for the solution of dynamic problems. In particular, it has shown a very stable and robust behavior with respect to the time step size required for convergence, even in cases where plasticity and fracture were considered. This paper presents another step toward enabling the prediction of progressive collapse of structures using MLF. A new gap element is added to the framework by formulating an additional component in the Lagrangian function. It is shown that by carefully formulating the new component, the optimization problem to be solved in each time step of the MLF algorithm retains its form which is quadratic in the cases considered. Hence, a unified formulation is attained for all stages of the analysis whether contact forces are present or not. After presenting details of the formulation, the proposed method is used for the solution of two examples. These examples illustrate that relatively large time steps can be considered even for contact problems. Furthermore, the reasons for this capability of the algorithm are discussed in the paper. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Dynamic analysis of gap closing and contact in the mixed lagrangian framework: toward progressive collapse prediction [texte imprimé] / Oren Lavan, Auteur . - pp. 979-986. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 136 N° 8 (Août 2010) . - pp. 979-986 Mots-clés : Progressive  collapse  Contact  Dynamic  analysis  Predictions Résumé : Previous research has shown many advantages of the mixed Lagrangian formulation (MLF) for the solution of dynamic problems. In particular, it has shown a very stable and robust behavior with respect to the time step size required for convergence, even in cases where plasticity and fracture were considered. This paper presents another step toward enabling the prediction of progressive collapse of structures using MLF. A new gap element is added to the framework by formulating an additional component in the Lagrangian function. It is shown that by carefully formulating the new component, the optimization problem to be solved in each time step of the MLF algorithm retains its form which is quadratic in the cases considered. Hence, a unified formulation is attained for all stages of the analysis whether contact forces are present or not. After presenting details of the formulation, the proposed method is used for the solution of two examples. These examples illustrate that relatively large time steps can be considered even for contact problems. Furthermore, the reasons for this capability of the algorithm are discussed in the paper. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]

Numerical collapse simulation of large-scale structural systems using an optimization-based algorithm / Sivaselvan, Mettupalayam V. 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. 655-677 Titre : Numerical collapse simulation of large-scale structural systems using an optimization-based algorithm Type de document : texte imprimé Auteurs : Sivaselvan, Mettupalayam V., Auteur ; Oren Lavan, Auteur ; Dargush, G. F., Auteur Article en page(s) : pp. 655-677 Note générale : Génie Cicil Langues : Anglais (eng) Mots-clés : nonlinear  dynamic  simulation  •  convex  optimization  •  generalized  standard  material  •  stored  energy  •  dissipation  potential  •  mixed  Lagrangian  formalism Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A new algorithm for nonlinear dynamic simulation of structures is presented. The algorithm is based on a mixed Lagrangian approach described by Sivaselvan and Reinhorn (J. Eng. Mech. (ASCE) 2006; 132(8):795-805). The algorithm developed in this paper is for the simulation of large-scale structural systems. The algorithm is applicable to a wide class of structural systems whose constituent material or component behavior can be derived from a stored energy function and a dissipation potential. The algorithm is based on the fact that for such systems, when using a certain class of time-discretization schemes to numerically compute the system response, the incremental problem of computing the system state at the next sample time knowing the current state and the input is one of convex minimization. As a result, the algorithm possesses excellent convergence characteristics. It is also applicable to geometric nonlinear problems. The implementation of the algorithm is described, and its applicability to the collapse analysis of large-scale structures is demonstrated through numerical examples. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121676918/abstract [article] Numerical collapse simulation of large-scale structural systems using an optimization-based algorithm [texte imprimé] / Sivaselvan, Mettupalayam V., Auteur ; Oren Lavan, Auteur ; Dargush, G. F., Auteur . - pp. 655-677. Génie Cicil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°5 (Avril 2009) . - pp. 655-677 Mots-clés : nonlinear  dynamic  simulation  •  convex  optimization  •  generalized  standard  material  •  stored  energy  •  dissipation  potential  •  mixed  Lagrangian  formalism Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A new algorithm for nonlinear dynamic simulation of structures is presented. The algorithm is based on a mixed Lagrangian approach described by Sivaselvan and Reinhorn (J. Eng. Mech. (ASCE) 2006; 132(8):795-805). The algorithm developed in this paper is for the simulation of large-scale structural systems. The algorithm is applicable to a wide class of structural systems whose constituent material or component behavior can be derived from a stored energy function and a dissipation potential. The algorithm is based on the fact that for such systems, when using a certain class of time-discretization schemes to numerically compute the system response, the incremental problem of computing the system state at the next sample time knowing the current state and the input is one of convex minimization. As a result, the algorithm possesses excellent convergence characteristics. It is also applicable to geometric nonlinear problems. The implementation of the algorithm is described, and its applicability to the collapse analysis of large-scale structures is demonstrated through numerical examples. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121676918/abstract