Documents disponibles écrits par cet auteur

Analytical assessment of the effect of vertical earthquake motion on RC bridge piers / Sung Jig Kim in Journal of structural engineering, Vol. 137 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 252-260 Titre : Analytical assessment of the effect of vertical earthquake motion on RC bridge piers Type de document : texte imprimé Auteurs : Sung Jig Kim, Auteur ; Curtis J. Holub, Auteur ; Amr S. Elnashai, Auteur Année de publication : 2011 Article en page(s) : pp. 252-260 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Vertical  loads  Ground  motion  Seismic  effects  Bridges  Piers  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents analytical assessment of the effect of vertical earthquake ground motion on RC bridge piers. A bridge structure damaged during the Northridge Earthquake and a Federal Highway concept bridge design are examined. The effects of a suite of earthquake ground motion records with different vertical-to-horizontal peak acceleration ratios on the two bridges are presented and the results are compared with the case of horizontal-only excitation. The effects of arrival time interval between horizontal and vertical acceleration peaks are also reported and compared to the case of coincident motion. It is observed that the inclusion of the vertical component of ground motion has an important effect on the response at all levels and components. It is therefore concluded that vertical motion should be included in analysis for assessment and design, especially that there are no particular challenges impeding its inclusion. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i2/p252_s1?isAuthorized=no [article] Analytical assessment of the effect of vertical earthquake motion on RC bridge piers [texte imprimé] / Sung Jig Kim, Auteur ; Curtis J. Holub, Auteur ; Amr S. Elnashai, Auteur . - 2011 . - pp. 252-260. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 252-260 Mots-clés : Vertical  loads  Ground  motion  Seismic  effects  Bridges  Piers  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents analytical assessment of the effect of vertical earthquake ground motion on RC bridge piers. A bridge structure damaged during the Northridge Earthquake and a Federal Highway concept bridge design are examined. The effects of a suite of earthquake ground motion records with different vertical-to-horizontal peak acceleration ratios on the two bridges are presented and the results are compared with the case of horizontal-only excitation. The effects of arrival time interval between horizontal and vertical acceleration peaks are also reported and compared to the case of coincident motion. It is observed that the inclusion of the vertical component of ground motion has an important effect on the response at all levels and components. It is therefore concluded that vertical motion should be included in analysis for assessment and design, especially that there are no particular challenges impeding its inclusion. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i2/p252_s1?isAuthorized=no

Behavior of concrete and ECC structures under simulated earthquake motion / Bora Gencturk 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. 389–399 Titre : Behavior of concrete and ECC structures under simulated earthquake motion Type de document : texte imprimé Auteurs : Bora Gencturk, Auteur ; Amr S. Elnashai, Auteur ; Michael D. Lepech, Auteur Année de publication : 2013 Article en page(s) : pp. 389–399 Note générale : structural engineering Langues : Anglais (eng) Mots-clés : reinforced  concrete;  ECC;  small-scale  testing;  experimental  methods;  hybrid  simulation;  stiffness;  strength;  ductility;  energy  absorption Résumé : The objective of the research presented in this paper is to investigate, experimentally, the effect of material- and section-level parameters on the structural response of concrete and engineered cementitious composite (ECC) buildings. In addition to testing of columns under monotonic, cyclic, and static-time history loading, hybrid simulation of structural frames is conducted. Stiffness, strength, ductility, and energy absorption capacity are selected as the response measures that represent the behavior of structures under seismic actions. The investigated variables are reinforcement ratios, ECC material properties, and axial load levels. The results are proposed as basic guidelines to determine the performance enhancement in terms of stiffness, strength, ductility, and energy absorption capacity, which could be achieved by replacing concrete with the high-performance material ECC. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000667 [article] Behavior of concrete and ECC structures under simulated earthquake motion [texte imprimé] / Bora Gencturk, Auteur ; Amr S. Elnashai, Auteur ; Michael D. Lepech, Auteur . - 2013 . - pp. 389–399. structural engineering Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 389–399 Mots-clés : reinforced  concrete;  ECC;  small-scale  testing;  experimental  methods;  hybrid  simulation;  stiffness;  strength;  ductility;  energy  absorption Résumé : The objective of the research presented in this paper is to investigate, experimentally, the effect of material- and section-level parameters on the structural response of concrete and engineered cementitious composite (ECC) buildings. In addition to testing of columns under monotonic, cyclic, and static-time history loading, hybrid simulation of structural frames is conducted. Stiffness, strength, ductility, and energy absorption capacity are selected as the response measures that represent the behavior of structures under seismic actions. The investigated variables are reinforcement ratios, ECC material properties, and axial load levels. The results are proposed as basic guidelines to determine the performance enhancement in terms of stiffness, strength, ductility, and energy absorption capacity, which could be achieved by replacing concrete with the high-performance material ECC. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000667

Global interventions for seismic upgrading of substandard RC buildings / G. E. Thermou in Journal of structural engineering, Vol. 138 N° 3 (Mars 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 387-401 Titre : Global interventions for seismic upgrading of substandard RC buildings Type de document : texte imprimé Auteurs : G. E. Thermou, Auteur ; S. J. Pantazopoulou, Auteur ; Amr S. Elnashai, Auteur Année de publication : 2012 Article en page(s) : pp. 387-401 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Buildings  Rehabilitation  Reinforced  concrete  Seismic  design  Columns  Walls Résumé : A methodology is developed in this paper for the design and proportioning of interventions for seismic upgrading of substandard reinforced-concrete (RC) buildings. The retrofit approach is presented in the form of a simple design tool that aims toward both demand reduction and enhancement of force and deformation supply through controlled modification of stiffness along the height of the building. This objective is achieved by engineering the translational mode-shape of the structure, so as to optimize the distribution of interstory drift. Results from the proposed approach are summarized in a spectrum format in which demand, expressed in terms of interstory drift, is related to stiffness. Design charts, which relate the characteristics of commonly used global intervention procedures to influence drift demands, are developed to facilitate the retrofit design. The intervention procedures considered in this paper are reinforced-concrete jacketing, the addition of reinforced-concrete walls, and the addition of masonry infills. The proposed methodology is also amenable to adaptation to other strengthening methods, such as the addition of cross-bracing. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i3/p387_s1?isAuthorized=no [article] Global interventions for seismic upgrading of substandard RC buildings [texte imprimé] / G. E. Thermou, Auteur ; S. J. Pantazopoulou, Auteur ; Amr S. Elnashai, Auteur . - 2012 . - pp. 387-401. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 387-401 Mots-clés : Buildings  Rehabilitation  Reinforced  concrete  Seismic  design  Columns  Walls Résumé : A methodology is developed in this paper for the design and proportioning of interventions for seismic upgrading of substandard reinforced-concrete (RC) buildings. The retrofit approach is presented in the form of a simple design tool that aims toward both demand reduction and enhancement of force and deformation supply through controlled modification of stiffness along the height of the building. This objective is achieved by engineering the translational mode-shape of the structure, so as to optimize the distribution of interstory drift. Results from the proposed approach are summarized in a spectrum format in which demand, expressed in terms of interstory drift, is related to stiffness. Design charts, which relate the characteristics of commonly used global intervention procedures to influence drift demands, are developed to facilitate the retrofit design. The intervention procedures considered in this paper are reinforced-concrete jacketing, the addition of reinforced-concrete walls, and the addition of masonry infills. The proposed methodology is also amenable to adaptation to other strengthening methods, such as the addition of cross-bracing. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i3/p387_s1?isAuthorized=no

Seismic performance of semirigid moment-resisting frames under far and near field records / Nihan Dogramaci Aksoylar in Journal of structural engineering, Vol. 138 N° 2 (Fevrier 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 2 (Fevrier 2012) . - pp. 157-169 Titre : Seismic performance of semirigid moment-resisting frames under far and near field records Type de document : texte imprimé Auteurs : Nihan Dogramaci Aksoylar, Auteur ; Amr S. Elnashai, Auteur ; Hussam Mahmoud, Auteur Année de publication : 2012 Article en page(s) : pp. 157-169 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Connections  Semirigid  Steel  frames  Seismic  analysis Résumé : The seismic performance of low-rise frames with energy dissipative semirigid connections is evaluated under far and near field artificial ground motion records. Four different connection capacities are employed in the frames and are characterized by two different moment-hardening ratios and two different hysteresis models. Nonlinear time-history and Fourier analyses are utilized to assess the seismic performance of 24 semirigid and 2 rigid frames. In the nonlinear time-history analyses, nine far field and nine near field artificial ground motion records generated from three different attenuation relations are used. Finally, the seismic performance of the rigid frames and the semirigid frames are compared, and the conditions under which the semirigid frames show better seismic performance than rigid frames are investigated. The results show that 25 of 26 sample frames satisfy all acceptance criteria and exhibit reliable seismic performance. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i2/p157_s1?isAuthorized=no [article] Seismic performance of semirigid moment-resisting frames under far and near field records [texte imprimé] / Nihan Dogramaci Aksoylar, Auteur ; Amr S. Elnashai, Auteur ; Hussam Mahmoud, Auteur . - 2012 . - pp. 157-169. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 2 (Fevrier 2012) . - pp. 157-169 Mots-clés : Connections  Semirigid  Steel  frames  Seismic  analysis Résumé : The seismic performance of low-rise frames with energy dissipative semirigid connections is evaluated under far and near field artificial ground motion records. Four different connection capacities are employed in the frames and are characterized by two different moment-hardening ratios and two different hysteresis models. Nonlinear time-history and Fourier analyses are utilized to assess the seismic performance of 24 semirigid and 2 rigid frames. In the nonlinear time-history analyses, nine far field and nine near field artificial ground motion records generated from three different attenuation relations are used. Finally, the seismic performance of the rigid frames and the semirigid frames are compared, and the conditions under which the semirigid frames show better seismic performance than rigid frames are investigated. The results show that 25 of 26 sample frames satisfy all acceptance criteria and exhibit reliable seismic performance. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i2/p157_s1?isAuthorized=no

Sensitivity-based external calibration of multiaxial loading system / Nakata, Narutoshi in Journal of engineering mechanics, Vol. 136 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 136 N° 2 (Fevrier 2010) . - pp. 189-19 Titre : Sensitivity-based external calibration of multiaxial loading system Type de document : texte imprimé Auteurs : Nakata, Narutoshi, Auteur ; Spencer, Billie F., Auteur ; Amr S. Elnashai, Auteur Article en page(s) : pp. 189-19 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Sensitivity  analysis  Calibration  Transformation. Résumé : Due to the nonlinear nature of coordinate transformations, evaluation and calibration of multiaxial loading systems in global Cartesian coordinates are challenging problems. This study proposes a systematic calibration method for multiaxial loading systems in global coordinates using an external measurement system. Global coordinate measurement for a multiaxial loading system is usually obtained from a geometric transformation based on internal actuator measurements. However, any misrepresentation of initial actuator configuration (e.g., origin, pin locations, etc.) introduces errors and cross-talk in the global Cartesian coordinates. Such errors and cross-talk cannot be observed or eliminated based on internal measurements. The method proposed in this paper is based on the sensitivity of the global coordinates with respect to the initial actuator length. To validate the proposed method, calibration is performed using the state-of-the-art Load and Boundary Condition Box at University of Illinois at Urbana-Champaign as the multiaxial loading system and the Krypton Dynamic Measurement Machine as the external measurement system. Experimental results demonstrate that the proposed sensitivity-based external calibration method is effective for improving control accuracy and reducing cross-talk of multiaxial loading systems in global Cartesian coordinates. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Sensitivity-based external calibration of multiaxial loading system [texte imprimé] / Nakata, Narutoshi, Auteur ; Spencer, Billie F., Auteur ; Amr S. Elnashai, Auteur . - pp. 189-19. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 136 N° 2 (Fevrier 2010) . - pp. 189-19 Mots-clés : Sensitivity  analysis  Calibration  Transformation. Résumé : Due to the nonlinear nature of coordinate transformations, evaluation and calibration of multiaxial loading systems in global Cartesian coordinates are challenging problems. This study proposes a systematic calibration method for multiaxial loading systems in global coordinates using an external measurement system. Global coordinate measurement for a multiaxial loading system is usually obtained from a geometric transformation based on internal actuator measurements. However, any misrepresentation of initial actuator configuration (e.g., origin, pin locations, etc.) introduces errors and cross-talk in the global Cartesian coordinates. Such errors and cross-talk cannot be observed or eliminated based on internal measurements. The method proposed in this paper is based on the sensitivity of the global coordinates with respect to the initial actuator length. To validate the proposed method, calibration is performed using the state-of-the-art Load and Boundary Condition Box at University of Illinois at Urbana-Champaign as the multiaxial loading system and the Krypton Dynamic Measurement Machine as the external measurement system. Experimental results demonstrate that the proposed sensitivity-based external calibration method is effective for improving control accuracy and reducing cross-talk of multiaxial loading systems in global Cartesian coordinates. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]

Simulation-based fragility relationships for unreinforced masonry buildings / Thomas M. Frankie in Journal of structural engineering, Vol. 139 N° 3 (Mars 2013) 

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Substructure hybrid simulation with multiple - support excitation / Jian Li in Journal of engineering mechanics, Vol. 138 N° 7 (Juillet 2012) 

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