Documents disponibles écrits par cet auteur

Analytical model and experimental study of failure behavior of thin-walled shallow concrete domes / Ehab Hamed in Journal of structural engineering, Vol. 137 N° 1 (Janvier 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 1 (Janvier 2011) . - pp. 88-99 Titre : Analytical model and experimental study of failure behavior of thin-walled shallow concrete domes Type de document : texte imprimé Auteurs : Ehab Hamed, Auteur ; Bradford, Mark A., Auteur ; R. Ian Gilbert, Auteur Année de publication : 2011 Article en page(s) : pp. 88-99 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Buckling  Concrete  Cracks  creep  Domes  Nonlinear  Shells Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The failure behavior of thin-walled shallow concrete domes under short-term and long-term loading is investigated theoretically and experimentally. The paper focuses on the long-term effects of creep and shrinkage, the material nonlinearity of the concrete under biaxial loading, and the geometric nonlinearity aspects of the structure through the development of nonlinear theoretical models for the short-term and long-term analyses. Special attention to the phenomenon of creep buckling is given in the development of the model, but without considering the nonaxisymmetric bifurcation response. The experimental phase involves the testing of two shallow domes. The first is loaded to failure under a gradually increasing pressure. The second dome is subjected to a constant sustained pressure for a period of 2.5 months. A series of tests for the characterization of the mechanical properties of the concrete, and its creep and shrinkage characteristics is also reported. The results and the theoretical-experimental comparison provide insight into the failure behavior of shallow concrete domes under both short-term and sustained loading, and contribute to the understanding of failure behavior of general concrete shells. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i1/p88_s1?isAuthorized=no [article] Analytical model and experimental study of failure behavior of thin-walled shallow concrete domes [texte imprimé] / Ehab Hamed, Auteur ; Bradford, Mark A., Auteur ; R. Ian Gilbert, Auteur . - 2011 . - pp. 88-99. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 1 (Janvier 2011) . - pp. 88-99 Mots-clés : Buckling  Concrete  Cracks  creep  Domes  Nonlinear  Shells Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The failure behavior of thin-walled shallow concrete domes under short-term and long-term loading is investigated theoretically and experimentally. The paper focuses on the long-term effects of creep and shrinkage, the material nonlinearity of the concrete under biaxial loading, and the geometric nonlinearity aspects of the structure through the development of nonlinear theoretical models for the short-term and long-term analyses. Special attention to the phenomenon of creep buckling is given in the development of the model, but without considering the nonaxisymmetric bifurcation response. The experimental phase involves the testing of two shallow domes. The first is loaded to failure under a gradually increasing pressure. The second dome is subjected to a constant sustained pressure for a period of 2.5 months. A series of tests for the characterization of the mechanical properties of the concrete, and its creep and shrinkage characteristics is also reported. The results and the theoretical-experimental comparison provide insight into the failure behavior of shallow concrete domes under both short-term and sustained loading, and contribute to the understanding of failure behavior of general concrete shells. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i1/p88_s1?isAuthorized=no

Free out-of-plane vibrations of masonry walls strengthened with composite materials / Ehab Hamed in Journal of engineering mechanics, Vol. 137 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 137 N° 2 (Fevrier 2011) . - pp.125-137 Titre : Free out-of-plane vibrations of masonry walls strengthened with composite materials Type de document : texte imprimé Auteurs : Ehab Hamed, Auteur ; Rabinovitch, Oded, Auteur Année de publication : 2011 Article en page(s) : pp.125-137 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Composite  materials  Free  vibration  Masonry  walls  Natural  frequencies  Strengthening  Nonlinear  analysis Résumé : The natural frequencies and the out-of-plane vibration modes of one-way masonry walls strengthened with composite materials are studied. Due to the inherent nonlinear behavior of the masonry wall, the dynamic characteristics depend on the level of out-of-plane load (mechanical load or forced out-of-plane deflections) and the resulting cracking, nonlinear behavior of the mortar material, and debonding of the composite system. In order to account for the nonlinearity and the accumulation of damage, a general nonlinear dynamic model of the strengthened wall is developed. The model is mathematically decomposed into a nonlinear static analysis phase, in which the static response and the corresponding residual mechanical properties are determined, and a free vibration analysis phase, in which the dynamic characteristics are determined. The governing nonlinear differential equations of the first phase, the linear differential eigenvalue problem corresponding to the second phase, and the solution strategies are derived. Two numerical examples that examine the capabilities of the model and study the dynamic properties of the strengthened wall are presented. The model is supported and verified through comparison with a step-by-step time integration analysis, and comparison with experimental results of a full-scale strengthened wall under impulse loading. The results show that the strengthening system significantly affects the natural frequencies of the wall, modifies its modes of vibration, and restrains the deterioration of the dynamic properties with the increase of load. The quantification of these effects contributes to the understanding of the performance of damaged strengthened walls under dynamic and seismic loads. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i2/p125_s1?isAuthorized=no [article] Free out-of-plane vibrations of masonry walls strengthened with composite materials [texte imprimé] / Ehab Hamed, Auteur ; Rabinovitch, Oded, Auteur . - 2011 . - pp.125-137. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 137 N° 2 (Fevrier 2011) . - pp.125-137 Mots-clés : Composite  materials  Free  vibration  Masonry  walls  Natural  frequencies  Strengthening  Nonlinear  analysis Résumé : The natural frequencies and the out-of-plane vibration modes of one-way masonry walls strengthened with composite materials are studied. Due to the inherent nonlinear behavior of the masonry wall, the dynamic characteristics depend on the level of out-of-plane load (mechanical load or forced out-of-plane deflections) and the resulting cracking, nonlinear behavior of the mortar material, and debonding of the composite system. In order to account for the nonlinearity and the accumulation of damage, a general nonlinear dynamic model of the strengthened wall is developed. The model is mathematically decomposed into a nonlinear static analysis phase, in which the static response and the corresponding residual mechanical properties are determined, and a free vibration analysis phase, in which the dynamic characteristics are determined. The governing nonlinear differential equations of the first phase, the linear differential eigenvalue problem corresponding to the second phase, and the solution strategies are derived. Two numerical examples that examine the capabilities of the model and study the dynamic properties of the strengthened wall are presented. The model is supported and verified through comparison with a step-by-step time integration analysis, and comparison with experimental results of a full-scale strengthened wall under impulse loading. The results show that the strengthening system significantly affects the natural frequencies of the wall, modifies its modes of vibration, and restrains the deterioration of the dynamic properties with the increase of load. The quantification of these effects contributes to the understanding of the performance of damaged strengthened walls under dynamic and seismic loads. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i2/p125_s1?isAuthorized=no