Documents disponibles écrits par cet auteur

Approximations in progressive collapse modeling / Alashker, Yasser in Journal of structural engineering, Vol. 137 N° 9 (Septembre 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 9 (Septembre 2011) . - pp. 914-924 Titre : Approximations in progressive collapse modeling Type de document : texte imprimé Auteurs : Alashker, Yasser, Auteur ; Honghao Li, Auteur ; Sherif El-Tawil, Auteur Année de publication : 2011 Article en page(s) : pp. 914-924 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Collapse  Model  Macro  model  Composite  Seismic  Steel  Failure Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Assumptions must necessarily be made when the collapse response of structures is investigated using simulation models. The type and extent of modeling assumptions depend on the computational resources available, modeling expertise, and results sought. Modeling choices that are commonly made include planar versus three-dimensional (3D) representation, simplification of member response for modeling purposes, and the use of macroelements to mimic behavior instead of using elements that are based on fundamental constitutive relationships. Using four different types of models, this paper sheds light on the effect of some commonly employed approximations in collapse modeling. The models represent a 10-story seismically designed steel building and encompass computationally expedient planar and 3D macromodels as well as continuum models of individual frames and the full 3D structural system. After a validation exercise, the simulation models are exercised to investigate system collapse response when columns are forcibly removed and to highlight the effects of the various modeling approaches. The simulation studies show that the floor system contributes significantly to collapse response. It is also shown that well calibrated macromodels can be relied on for accuracy when modeling progressive collapse and that the results of planar analyses cannot always be viewed as conservative. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i9/p914_s1?bypassSSO=1 [article] Approximations in progressive collapse modeling [texte imprimé] / Alashker, Yasser, Auteur ; Honghao Li, Auteur ; Sherif El-Tawil, Auteur . - 2011 . - pp. 914-924. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 9 (Septembre 2011) . - pp. 914-924 Mots-clés : Collapse  Model  Macro  model  Composite  Seismic  Steel  Failure Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Assumptions must necessarily be made when the collapse response of structures is investigated using simulation models. The type and extent of modeling assumptions depend on the computational resources available, modeling expertise, and results sought. Modeling choices that are commonly made include planar versus three-dimensional (3D) representation, simplification of member response for modeling purposes, and the use of macroelements to mimic behavior instead of using elements that are based on fundamental constitutive relationships. Using four different types of models, this paper sheds light on the effect of some commonly employed approximations in collapse modeling. The models represent a 10-story seismically designed steel building and encompass computationally expedient planar and 3D macromodels as well as continuum models of individual frames and the full 3D structural system. After a validation exercise, the simulation models are exercised to investigate system collapse response when columns are forcibly removed and to highlight the effects of the various modeling approaches. The simulation studies show that the floor system contributes significantly to collapse response. It is also shown that well calibrated macromodels can be relied on for accuracy when modeling progressive collapse and that the results of planar analyses cannot always be viewed as conservative. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i9/p914_s1?bypassSSO=1

Progressive collapse resistance of steel-concrete composite floors / Alashker, Yasser in Journal of structural engineering, Vol. 136 N° 10 (Octobre 2010) 

Public ISBD [article]  in Journal of structural engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1187-1196 Titre : Progressive collapse resistance of steel-concrete composite floors Type de document : texte imprimé Auteurs : Alashker, Yasser, Auteur ; Sherif El-Tawil, Auteur ; Sadek, Fahim, Auteur Année de publication : 2011 Article en page(s) : pp. 1187-1196 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Composite  floor  systems  Robustness  Disproportionate  collapse  Finite-element  analysis  Progressive  collapse  Shear  connections  Shear  tab  Connection Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper discusses the progressive collapse resistance of steel-concrete composite floors in which steel beams are attached to columns through shear tabs. This is a common type of system used for the gravity bay portions of steel buildings. The study is conducted using computational simulation models validated through extensive comparisons to disparate test data. The models are used to investigate key parameters influencing the robustness of generic composite floors subjected to the removal of a center column. In particular, the effects of deck thickness, steel reinforcement, and the numbers of bolts in the shear tab connection on the behavior of the system are studied as a function of the loading scheme. The simulation results show that the majority of collapse resistance comes from the steel deck and that, for the system considered, increasing connection strength by adding more bolts might not be that beneficial in increasing overall collapse strength. The dynamic impact factor, which is widely used to account for dynamic effects within a static design framework, is also computed and the DIF value recommended in existing design guidelines is evaluated. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i10/p1187_s1?isAuthorized=no [article] Progressive collapse resistance of steel-concrete composite floors [texte imprimé] / Alashker, Yasser, Auteur ; Sherif El-Tawil, Auteur ; Sadek, Fahim, Auteur . - 2011 . - pp. 1187-1196. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1187-1196 Mots-clés : Composite  floor  systems  Robustness  Disproportionate  collapse  Finite-element  analysis  Progressive  collapse  Shear  connections  Shear  tab  Connection Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper discusses the progressive collapse resistance of steel-concrete composite floors in which steel beams are attached to columns through shear tabs. This is a common type of system used for the gravity bay portions of steel buildings. The study is conducted using computational simulation models validated through extensive comparisons to disparate test data. The models are used to investigate key parameters influencing the robustness of generic composite floors subjected to the removal of a center column. In particular, the effects of deck thickness, steel reinforcement, and the numbers of bolts in the shear tab connection on the behavior of the system are studied as a function of the loading scheme. The simulation results show that the majority of collapse resistance comes from the steel deck and that, for the system considered, increasing connection strength by adding more bolts might not be that beneficial in increasing overall collapse strength. The dynamic impact factor, which is widely used to account for dynamic effects within a static design framework, is also computed and the DIF value recommended in existing design guidelines is evaluated. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i10/p1187_s1?isAuthorized=no