Documents disponibles écrits par cet auteur

Cuclic flexural testing of concentrically braced frame beam-column connections / Christopher D. Stoakes in Journal of structural engineering, Vol. 137 N° 7 (Juillet 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 7 (Juillet 2011) . - pp. 739-747 Titre : Cuclic flexural testing of concentrically braced frame beam-column connections Type de document : texte imprimé Auteurs : Christopher D. Stoakes, Auteur ; Larry A. Fahnestock, Auteur Année de publication : 2011 Article en page(s) : pp. 739-747 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Reserve  capacity  Braced  frames  Beam-column  connections  Low-ductility  systems Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This research investigates the cyclic flexural behavior and performance of concentrically braced frame beam-column connections in the context of evaluating the reserve lateral load-resisting capacity in concentrically braced frames. Eight beam-column connections with gusset plates, employing double angle and end plate details, were studied using full-scale experiments to determine their flexural strength, stiffness, and ductility. In this paper, the effects of connection parameters, such as end plate thickness, angle thickness, bolt configuration, weld type and size, and supplementary seat angle, are evaluated. The global connection behavior and performance are quantified using normalized moment versus story drift data. In comparison to a baseline double angle detail, all connection variations increased the strength and stiffness. The end plate variations resulted in larger increases in strength, but drift capacity was limited by bolt fracture. The double angle variations increased the strength by smaller margins, but strength loss occurred more gradually, and larger drifts were sustained. The double angle connection configuration with a supplemental seat angle is shown to provide the best balance of strength and deformation capacity. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i7/p739_s1?isAuthorized=no [article] Cuclic flexural testing of concentrically braced frame beam-column connections [texte imprimé] / Christopher D. Stoakes, Auteur ; Larry A. Fahnestock, Auteur . - 2011 . - pp. 739-747. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 7 (Juillet 2011) . - pp. 739-747 Mots-clés : Reserve  capacity  Braced  frames  Beam-column  connections  Low-ductility  systems Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This research investigates the cyclic flexural behavior and performance of concentrically braced frame beam-column connections in the context of evaluating the reserve lateral load-resisting capacity in concentrically braced frames. Eight beam-column connections with gusset plates, employing double angle and end plate details, were studied using full-scale experiments to determine their flexural strength, stiffness, and ductility. In this paper, the effects of connection parameters, such as end plate thickness, angle thickness, bolt configuration, weld type and size, and supplementary seat angle, are evaluated. The global connection behavior and performance are quantified using normalized moment versus story drift data. In comparison to a baseline double angle detail, all connection variations increased the strength and stiffness. The end plate variations resulted in larger increases in strength, but drift capacity was limited by bolt fracture. The double angle variations increased the strength by smaller margins, but strength loss occurred more gradually, and larger drifts were sustained. The double angle connection configuration with a supplemental seat angle is shown to provide the best balance of strength and deformation capacity. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i7/p739_s1?isAuthorized=no

Impact of residual stresses and initial imperfections on the seismic response of steel moment frames / Kapil Mathur in Journal of structural engineering, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 942–951 Titre : Impact of residual stresses and initial imperfections on the seismic response of steel moment frames Type de document : texte imprimé Auteurs : Kapil Mathur, Auteur ; Larry A. Fahnestock, Auteur ; Taichiro Okazaki, Auteur Année de publication : 2012 Article en page(s) : pp. 942–951 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Direct  analysis  method  Steel  moment  frames  Connection  cyclic  strength  degradation Résumé : The 2010 AISC specification establishes the direct analysis method (DM) as the standard stability analysis and design procedure. Although the DM has important benefits over conventional stability design methods, the interface between the DM, the AISC seismic provisions, and the seismic design requirements in ASCE-7 is not fully established. Because the DM, which was developed for design scenarios that do not contain seismic loading, includes the effects of initial geometric imperfections and inelastic behavior owing to residual stresses, it is critical to explore the impact of these parameters on the seismic behavior of typical steel buildings. To examine these issues, a series of steel special moment-resisting frame models were subjected to monotonic pushover, cyclic pushover, and response history analyses. The observed behavior was used to draw comparisons between systems with and without residual stresses and initial imperfections. Cyclic strength degradation at beam-to-column connections was also considered to examine the potential interaction it may have with the other parameters. Whereas the well-known impact of strength degradation on cyclic stability was noted, residual stresses and initial imperfections did not have any appreciable effect on stability behavior for the systems considered. The analyses conducted in this study indicate no clear benefit to using the DM when designing regular ductile steel systems in high seismic regions and simpler design methods may be equally effective. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000512 [article] Impact of residual stresses and initial imperfections on the seismic response of steel moment frames [texte imprimé] / Kapil Mathur, Auteur ; Larry A. Fahnestock, Auteur ; Taichiro Okazaki, Auteur . - 2012 . - pp. 942–951. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 942–951 Mots-clés : Direct  analysis  method  Steel  moment  frames  Connection  cyclic  strength  degradation Résumé : The 2010 AISC specification establishes the direct analysis method (DM) as the standard stability analysis and design procedure. Although the DM has important benefits over conventional stability design methods, the interface between the DM, the AISC seismic provisions, and the seismic design requirements in ASCE-7 is not fully established. Because the DM, which was developed for design scenarios that do not contain seismic loading, includes the effects of initial geometric imperfections and inelastic behavior owing to residual stresses, it is critical to explore the impact of these parameters on the seismic behavior of typical steel buildings. To examine these issues, a series of steel special moment-resisting frame models were subjected to monotonic pushover, cyclic pushover, and response history analyses. The observed behavior was used to draw comparisons between systems with and without residual stresses and initial imperfections. Cyclic strength degradation at beam-to-column connections was also considered to examine the potential interaction it may have with the other parameters. Whereas the well-known impact of strength degradation on cyclic stability was noted, residual stresses and initial imperfections did not have any appreciable effect on stability behavior for the systems considered. The analyses conducted in this study indicate no clear benefit to using the DM when designing regular ductile steel systems in high seismic regions and simpler design methods may be equally effective. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000512

Seismic design and viability of hybrid masonry building systems / Maryam Eidini in Journal of structural engineering, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 411–421 Titre : Seismic design and viability of hybrid masonry building systems Type de document : texte imprimé Auteurs : Maryam Eidini, Auteur ; Daniel P. Abrams, Auteur ; Larry A. Fahnestock, Auteur Année de publication : 2013 Article en page(s) : pp. 411–421 Note générale : structural engineering Langues : Anglais (eng) Mots-clés : seismic  design;  masonry;  steel  frames;  connections;  ductility;  hybrid  methods;  building  design Résumé : Hybrid masonry is an innovative technology for seismic design of buildings. The system uses reinforced masonry panels within a steel-framed structure, where steel connector plates link the steel frame to the masonry panels. The system has been used for construction of low-rise buildings in the low-seismic regions of the eastern and midwestern United States but has not been implemented in regions of moderate or high seismicity yet. Current research is underway to extend the application of hybrid masonry for use in high-seismic regions. In this paper, the overall approach for seismic design of one type of hybrid masonry systems is studied, and the steps of a capacity design process are presented, where two favorable ductile modes of behavior may be exploited: steel connector plates behaving as fuses or flexural yielding of the masonry panels. Moreover, this research applies the two design options for 3-, 6-, and 9-story prototype buildings located in a high seismic region and evaluates viability of hybrid masonry as a new seismic lateral-load resisting system. On the basis of this design framework and the exploratory studies, both approaches are shown to be feasible for developing realistic system configurations. Nevertheless, for the case of flexural yielding of the masonry panels, the steel connector plates must carry significant shear force demands. The structural system then requires more hybrid panels compared with corresponding systems when plasticity is concentrated in the steel connector plates. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000672 [article] Seismic design and viability of hybrid masonry building systems [texte imprimé] / Maryam Eidini, Auteur ; Daniel P. Abrams, Auteur ; Larry A. Fahnestock, Auteur . - 2013 . - pp. 411–421. structural engineering Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 411–421 Mots-clés : seismic  design;  masonry;  steel  frames;  connections;  ductility;  hybrid  methods;  building  design Résumé : Hybrid masonry is an innovative technology for seismic design of buildings. The system uses reinforced masonry panels within a steel-framed structure, where steel connector plates link the steel frame to the masonry panels. The system has been used for construction of low-rise buildings in the low-seismic regions of the eastern and midwestern United States but has not been implemented in regions of moderate or high seismicity yet. Current research is underway to extend the application of hybrid masonry for use in high-seismic regions. In this paper, the overall approach for seismic design of one type of hybrid masonry systems is studied, and the steps of a capacity design process are presented, where two favorable ductile modes of behavior may be exploited: steel connector plates behaving as fuses or flexural yielding of the masonry panels. Moreover, this research applies the two design options for 3-, 6-, and 9-story prototype buildings located in a high seismic region and evaluates viability of hybrid masonry as a new seismic lateral-load resisting system. On the basis of this design framework and the exploratory studies, both approaches are shown to be feasible for developing realistic system configurations. Nevertheless, for the case of flexural yielding of the masonry panels, the steel connector plates must carry significant shear force demands. The structural system then requires more hybrid panels compared with corresponding systems when plasticity is concentrated in the steel connector plates. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000672

Seismic response of single-degree-of-freedom systems representing low-ductility steel concentrically braced frames with reserve capacity / Gang Li in Journal of structural engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 2 (Février 2013) . - pp. 199–211 Titre : Seismic response of single-degree-of-freedom systems representing low-ductility steel concentrically braced frames with reserve capacity Type de document : texte imprimé Auteurs : Gang Li, Auteur ; Larry A. Fahnestock, Auteur Année de publication : 2013 Article en page(s) : pp. 199–211 Note générale : structural engineering Langues : Anglais (eng) Mots-clés : buildings;  steel  frames;  seismic  analysis;  dynamic  response;  bracing;  structural  response Résumé : Steel concentrically braced frames (CBFs) are used widely as a seismic lateral force–resisting system. Although modern CBFs designed for high seismic regions have considerable ductility, CBFs in moderate seismic regions are expected to have limited ductility, even when designed using modern provisions. In addition, older CBFs in high seismic regions also are expected to have limited ductility. In these low-ductility systems, reserve capacity (i.e., secondary strength and stiffness) plays an important role in seismic collapse prevention. Thus, quantifying the impact of reserve capacity on earthquake response for low-ductility systems is critical. This paper presents research that used single-degree-of-freedom systems to represent low-ductility CBFs, where brace fracture causes a sudden loss of strength and stiffness. Postbrace fracture stability was studied by considering variations in reserve system strength and stiffness parameters. Performance was evaluated by considering local ductility demands on the reserve system and global drift demands. For the cases considered, the ductility capacity of the reserve system was typically a more critical constraint than global drift capacity. Reserve capacity is demonstrated to appreciably influence seismic collapse behavior, whereas primary system strength has a small influence. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000629 [article] Seismic response of single-degree-of-freedom systems representing low-ductility steel concentrically braced frames with reserve capacity [texte imprimé] / Gang Li, Auteur ; Larry A. Fahnestock, Auteur . - 2013 . - pp. 199–211. structural engineering Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 2 (Février 2013) . - pp. 199–211 Mots-clés : buildings;  steel  frames;  seismic  analysis;  dynamic  response;  bracing;  structural  response Résumé : Steel concentrically braced frames (CBFs) are used widely as a seismic lateral force–resisting system. Although modern CBFs designed for high seismic regions have considerable ductility, CBFs in moderate seismic regions are expected to have limited ductility, even when designed using modern provisions. In addition, older CBFs in high seismic regions also are expected to have limited ductility. In these low-ductility systems, reserve capacity (i.e., secondary strength and stiffness) plays an important role in seismic collapse prevention. Thus, quantifying the impact of reserve capacity on earthquake response for low-ductility systems is critical. This paper presents research that used single-degree-of-freedom systems to represent low-ductility CBFs, where brace fracture causes a sudden loss of strength and stiffness. Postbrace fracture stability was studied by considering variations in reserve system strength and stiffness parameters. Performance was evaluated by considering local ductility demands on the reserve system and global drift demands. For the cases considered, the ductility capacity of the reserve system was typically a more critical constraint than global drift capacity. Reserve capacity is demonstrated to appreciably influence seismic collapse behavior, whereas primary system strength has a small influence. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000629