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Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections / Hyung-Joon Kim 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. 1-21 Titre : Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections Type de document : texte imprimé Auteurs : Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur Article en page(s) : pp. 1-21 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Post-tension;  Self-centering;  Energy  dissipating  devices  ;  Numerical  models;  Flexural  hinges Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : New steel moment-resisting connections that incorporate post-tensioning elements to provide a self-centering capacity and devices to dissipate seismic input energy have recently been proposed and experimentally validated. Experimental studies have confirmed that these connections are capable of undergoing large lateral deformations with negligible residual drifts. To facilitate their implementation, accurate modeling of the behavior of systems incorporating post-tensioned connections must be readily available to designers and researchers. A number of simplified models have been suggested in the literature by researchers trying to capture experimental results at the beam-column connections and thereby to predict the global response of structures incorporating such connections. To provide a clear set of guidelines for the modeling of post-tensioned steel frames, for practicing engineers as well as researchers, in this paper three types of numerical models of increasing complexity are presented: (i) a sectional analysis procedure, (ii) a lumped plasticity spring frame leveled approach and (iii) a non-linear solid finite element analysis to predict the response at ultimate deformation levels. The analytical results obtained from the numerical models predict well the structural behavior of these connections when compared with available experimental data. Even at the ultimate deformation level, analytical results are in good agreement with test results. Furthermore, detailing requirements are proposed to assure that flexural hinges form in the beams in order to improve the cyclic response of steel self-centering connections when drifts exceeding the design drifts are imposed to the system. Experimental and analytical studies demonstrate that steel post-tensioned self-centering connections incorporating the proposed detailing in the beams develop an increased deformation capacity and thereby exhibit a ductile response while avoiding a sudden loss of their strength and stiffness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121356228/abstract [article] Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections [texte imprimé] / Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur . - pp. 1-21. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 1-21 Mots-clés : Post-tension;  Self-centering;  Energy  dissipating  devices  ;  Numerical  models;  Flexural  hinges Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : New steel moment-resisting connections that incorporate post-tensioning elements to provide a self-centering capacity and devices to dissipate seismic input energy have recently been proposed and experimentally validated. Experimental studies have confirmed that these connections are capable of undergoing large lateral deformations with negligible residual drifts. To facilitate their implementation, accurate modeling of the behavior of systems incorporating post-tensioned connections must be readily available to designers and researchers. A number of simplified models have been suggested in the literature by researchers trying to capture experimental results at the beam-column connections and thereby to predict the global response of structures incorporating such connections. To provide a clear set of guidelines for the modeling of post-tensioned steel frames, for practicing engineers as well as researchers, in this paper three types of numerical models of increasing complexity are presented: (i) a sectional analysis procedure, (ii) a lumped plasticity spring frame leveled approach and (iii) a non-linear solid finite element analysis to predict the response at ultimate deformation levels. The analytical results obtained from the numerical models predict well the structural behavior of these connections when compared with available experimental data. Even at the ultimate deformation level, analytical results are in good agreement with test results. Furthermore, detailing requirements are proposed to assure that flexural hinges form in the beams in order to improve the cyclic response of steel self-centering connections when drifts exceeding the design drifts are imposed to the system. Experimental and analytical studies demonstrate that steel post-tensioned self-centering connections incorporating the proposed detailing in the beams develop an increased deformation capacity and thereby exhibit a ductile response while avoiding a sudden loss of their strength and stiffness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121356228/abstract

Seismic design procedure and seismic response of post-tensioned self-centering steel frames / Hyung-Joon Kim in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 355-376 Titre : Seismic design procedure and seismic response of post-tensioned self-centering steel frames Type de document : texte imprimé Auteurs : Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur Article en page(s) : pp. 355-376 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Post-tension;  Self-centering;  Seismic  design  procedure  ;  Restraining  effects Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Post-tensioned (PT) self-centering moment-resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self-centering friction damped (SCFR) moment-resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self-centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment-resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self-centering steel frame system. A six-story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re-designed by the proposed seismic design procedure. Time-history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121461952/abstract [article] Seismic design procedure and seismic response of post-tensioned self-centering steel frames [texte imprimé] / Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur . - pp. 355-376. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 355-376 Mots-clés : Post-tension;  Self-centering;  Seismic  design  procedure  ;  Restraining  effects Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Post-tensioned (PT) self-centering moment-resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self-centering friction damped (SCFR) moment-resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self-centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment-resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self-centering steel frame system. A six-story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re-designed by the proposed seismic design procedure. Time-history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121461952/abstract