Documents disponibles écrits par cet auteur

Performance of steel moment connections under a column removal scenario / H. S. Lew in Journal of structural engineering, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 98–107 Titre : Performance of steel moment connections under a column removal scenario : I: Experiments Type de document : texte imprimé Auteurs : H. S. Lew, Auteur ; Joseph A. Main, Auteur ; Stephen D. Robert, Auteur Année de publication : 2013 Article en page(s) : pp. 98–107 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Buildings  Connections  Full-scale  tests  Progressive  collapse  Seismic  design  Steel  structures Résumé : This paper presents an experimental study of two full-scale steel beam-column assemblies, each comprising three columns and two beams, to (1) define their response characteristics under a column-removal scenario, including the capacity of the beams and their connections to carry loads through catenary action, and (2) provide experimental data for validation of beam-to-column connection models for assessing the robustness of structural systems. The assemblies represent portions of the exterior moment-resisting frames of two 10-story steel-frame buildings. One test specimen had welded unreinforced flange, bolted web connections, and the other had reduced beam–section connections. When subjected to monotonically increasing vertical displacement of the unsupported center column, both specimens exhibited an initial elastic response dominated by flexure. With increased vertical displacement, the connections yielded, and axial tension developed in the beams. The axial tension in the beams increased until the connections failed under combined bending and axial stresses. The test results show that the rotational capacities of both connections under monotonic column displacement are about twice as large as those based on seismic-test data. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000618 [article] Performance of steel moment connections under a column removal scenario : I: Experiments [texte imprimé] / H. S. Lew, Auteur ; Joseph A. Main, Auteur ; Stephen D. Robert, Auteur . - 2013 . - pp. 98–107. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 98–107 Mots-clés : Buildings  Connections  Full-scale  tests  Progressive  collapse  Seismic  design  Steel  structures Résumé : This paper presents an experimental study of two full-scale steel beam-column assemblies, each comprising three columns and two beams, to (1) define their response characteristics under a column-removal scenario, including the capacity of the beams and their connections to carry loads through catenary action, and (2) provide experimental data for validation of beam-to-column connection models for assessing the robustness of structural systems. The assemblies represent portions of the exterior moment-resisting frames of two 10-story steel-frame buildings. One test specimen had welded unreinforced flange, bolted web connections, and the other had reduced beam–section connections. When subjected to monotonically increasing vertical displacement of the unsupported center column, both specimens exhibited an initial elastic response dominated by flexure. With increased vertical displacement, the connections yielded, and axial tension developed in the beams. The axial tension in the beams increased until the connections failed under combined bending and axial stresses. The test results show that the rotational capacities of both connections under monotonic column displacement are about twice as large as those based on seismic-test data. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000618

Performance of steel moment connections under a column removal scenario / Sadek, Fahim in Journal of structural engineering, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 108–119 Titre : Performance of steel moment connections under a column removal scenario : II: Analysis Type de document : texte imprimé Auteurs : Sadek, Fahim, Auteur ; Joseph A. Main, Auteur ; H. S. Lew, Auteur Année de publication : 2013 Article en page(s) : pp. 108–119 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Buildings  Connections  FEM  Nonlinear  analysis  Progressive  collapse  Seismic  design  Steel  structures Résumé : This paper presents a computational investigation of the response of steel beam-column assemblies with moment connections under monotonic loading conditions simulating a column removal scenario. Two beam-column assemblies are analyzed, which incorporate (1) welded unreinforced flange bolted web connections, and (2) reduced beam section connections. Detailed models of the assemblies are developed, which use highly refined solid and shell elements to represent nonlinear material behavior and fracture. Reduced models are also developed, which use a much smaller number of beam and spring elements and are intended for use in future studies to assess the vulnerability of complete structural systems to disproportionate collapse. The two modeling approaches are described, and computational results are compared with the results of the full-scale tests described in the companion paper. Good agreement is observed, demonstrating that both the detailed and reduced models are capable of capturing the predominant response characteristics and failure modes of the assemblies, including the development of tensile forces associated with catenary action and the ultimate failure of the moment connections under combined bending and axial stresses. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000617 [article] Performance of steel moment connections under a column removal scenario : II: Analysis [texte imprimé] / Sadek, Fahim, Auteur ; Joseph A. Main, Auteur ; H. S. Lew, Auteur . - 2013 . - pp. 108–119. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 108–119 Mots-clés : Buildings  Connections  FEM  Nonlinear  analysis  Progressive  collapse  Seismic  design  Steel  structures Résumé : This paper presents a computational investigation of the response of steel beam-column assemblies with moment connections under monotonic loading conditions simulating a column removal scenario. Two beam-column assemblies are analyzed, which incorporate (1) welded unreinforced flange bolted web connections, and (2) reduced beam section connections. Detailed models of the assemblies are developed, which use highly refined solid and shell elements to represent nonlinear material behavior and fracture. Reduced models are also developed, which use a much smaller number of beam and spring elements and are intended for use in future studies to assess the vulnerability of complete structural systems to disproportionate collapse. The two modeling approaches are described, and computational results are compared with the results of the full-scale tests described in the companion paper. Good agreement is observed, demonstrating that both the detailed and reduced models are capable of capturing the predominant response characteristics and failure modes of the assemblies, including the development of tensile forces associated with catenary action and the ultimate failure of the moment connections under combined bending and axial stresses. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000617

Testing and analysis of steel and concrete beam-column assemblies under a column removal scenario / Sadek, Fahim 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. 881-892 Titre : Testing and analysis of steel and concrete beam-column assemblies under a column removal scenario Type de document : texte imprimé Auteurs : Sadek, Fahim, Auteur ; Joseph A. Main, Auteur ; H. S. Lew, Auteur Année de publication : 2011 Article en page(s) : pp. 881-892 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Buildings  Concrete  structures  Finite-element  method  Full-scale  tests  Nonlinear  analysis  Progressive  collapse  Seismic  design  Steel  structures Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents an experimental and computational assessment of the performance of steel and reinforced concrete beam-column assemblies under monotonic vertical displacement of a center column, simulating a column removal scenario. The assemblies represent portions of structural framing systems designed as intermediate moment frames (IMFs) and special moment frames (SMFs) for Seismic Design Categories C and D, respectively. The steel IMF and SMF assemblies were designed in accordance with ANSI/AISC 341-02 by using prequalified moment connections specified in FEMA 350. The concrete IMF and SMF assemblies were designed and detailed in accordance with ACI 318-02 requirements. Each full-scale assembly comprises two beam spans and three columns, and downward displacements of the center column are imposed until failure. The study provides insight into the behavior and failure modes of the assemblies, including the development of catenary action. Both detailed and reduced finite-element models are developed, which capture the primary response characteristics and failure modes. Analyses with the reduced models can be executed rapidly without loss of accuracy, facilitating implementation in models of entire structural systems. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i9/p881_s1?bypassSSO=1 [article] Testing and analysis of steel and concrete beam-column assemblies under a column removal scenario [texte imprimé] / Sadek, Fahim, Auteur ; Joseph A. Main, Auteur ; H. S. Lew, Auteur . - 2011 . - pp. 881-892. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 9 (Septembre 2011) . - pp. 881-892 Mots-clés : Buildings  Concrete  structures  Finite-element  method  Full-scale  tests  Nonlinear  analysis  Progressive  collapse  Seismic  design  Steel  structures Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents an experimental and computational assessment of the performance of steel and reinforced concrete beam-column assemblies under monotonic vertical displacement of a center column, simulating a column removal scenario. The assemblies represent portions of structural framing systems designed as intermediate moment frames (IMFs) and special moment frames (SMFs) for Seismic Design Categories C and D, respectively. The steel IMF and SMF assemblies were designed in accordance with ANSI/AISC 341-02 by using prequalified moment connections specified in FEMA 350. The concrete IMF and SMF assemblies were designed and detailed in accordance with ACI 318-02 requirements. Each full-scale assembly comprises two beam spans and three columns, and downward displacements of the center column are imposed until failure. The study provides insight into the behavior and failure modes of the assemblies, including the development of catenary action. Both detailed and reduced finite-element models are developed, which capture the primary response characteristics and failure modes. Analyses with the reduced models can be executed rapidly without loss of accuracy, facilitating implementation in models of entire structural systems. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i9/p881_s1?bypassSSO=1