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Lateral cyclic behavior of reinforced concrete columns retrofitted with shape memory spirals and FRP wraps / Moochul Shin in Journal of structural engineering, Vol. 137 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of structural engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1282-1290 Titre : Lateral cyclic behavior of reinforced concrete columns retrofitted with shape memory spirals and FRP wraps Type de document : texte imprimé Auteurs : Moochul Shin, Auteur ; Bassem Andrawes, Auteur Année de publication : 2012 Article en page(s) : pp. 1282-1290 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Active  confinement  Concrete  Bridges  Retrofitting  Shape  memory  alloys  Fiber-reinforced  polymers  Ductility  Structural  damage Résumé : This experimental work focuses on enhancing the lateral cyclic behavior of RC columns by using an innovative active-confinement technique. The thermally triggered recovery stress of prestrained shape memory alloy (SMA) spirals is used to apply the active-confinement pressure. Four 1/3-scale RC columns, three of which are retrofitted with different schemes, are tested under quasi-static lateral cyclic loading. The plastic hinge region of the first retrofitted column is actively confined using the new SMA spirals, whereas for the second column, traditional passive confinement is applied by using a glass fiber-reinforced polymer (GFRP)/epoxy jacket. The third column is retrofitted by using a hybrid confinement approach, which is applied by using SMA spirals and GFRP jacket simultaneously at the plastic hinge zone. The confinement pressure of the three retrofitted columns is designed to be the same. The results show a significant increase in the flexural ductility capacity and energy dissipation capability of the columns retrofitted with SMA spirals compared with those of the as-built column and the GFRP-retrofitted column. SMA spirals also show an outstanding ability to mitigate the damage sustained by the columns under extreme lateral drifts. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i11/p1282_s1?isAuthorized=no [article] Lateral cyclic behavior of reinforced concrete columns retrofitted with shape memory spirals and FRP wraps [texte imprimé] / Moochul Shin, Auteur ; Bassem Andrawes, Auteur . - 2012 . - pp. 1282-1290. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1282-1290 Mots-clés : Active  confinement  Concrete  Bridges  Retrofitting  Shape  memory  alloys  Fiber-reinforced  polymers  Ductility  Structural  damage Résumé : This experimental work focuses on enhancing the lateral cyclic behavior of RC columns by using an innovative active-confinement technique. The thermally triggered recovery stress of prestrained shape memory alloy (SMA) spirals is used to apply the active-confinement pressure. Four 1/3-scale RC columns, three of which are retrofitted with different schemes, are tested under quasi-static lateral cyclic loading. The plastic hinge region of the first retrofitted column is actively confined using the new SMA spirals, whereas for the second column, traditional passive confinement is applied by using a glass fiber-reinforced polymer (GFRP)/epoxy jacket. The third column is retrofitted by using a hybrid confinement approach, which is applied by using SMA spirals and GFRP jacket simultaneously at the plastic hinge zone. The confinement pressure of the three retrofitted columns is designed to be the same. The results show a significant increase in the flexural ductility capacity and energy dissipation capability of the columns retrofitted with SMA spirals compared with those of the as-built column and the GFRP-retrofitted column. SMA spirals also show an outstanding ability to mitigate the damage sustained by the columns under extreme lateral drifts. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v137/i11/p1282_s1?isAuthorized=no

Sensitivity of seismic applications to different shape memory alloy models / Bassem Andrawes in Journal of engineering mechanics, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.173–183. Titre : Sensitivity of seismic applications to different shape memory alloy models Type de document : texte imprimé Auteurs : Bassem Andrawes, Auteur ; Reginald DesRoches, Auteur Année de publication : 2008 Article en page(s) : pp.173–183. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Shape  memory  effect  Elasticity  Earthquakes  Constitutive  models  Seismic  effects  Sensitivity  anlysis. Résumé : Shape memory alloys (SMAs) are known for their superelastic properties, which have been exploited in numerous applications in the biomedical, aerospace, and commercial fields. More recently, these materials have been evaluated for applications in the area of earthquake engineering. One key question that arises when using these materials is the appropriate constitutive material model to use to capture the highly nonlinear behavior of SMAs. This paper explores the effect of using different SMA constitutive models on the resulting response of systems using SMAs. A sensitivity analysis is conducted by using three SMA models with various levels of complexity. The models are implemented in a single-degree-of-freedom system and subjected to three groups of earthquake records with various characteristics. Considering a more accurate trend in modeling incomplete cycles in SMAs has little impact on the structural response. The strength degradation and residual deformation seem to be of more importance than the sublooping behavior. The response is more sensitive to the cyclic effects in the case of records with long durations or large intensities. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2817 [...] [article] Sensitivity of seismic applications to different shape memory alloy models [texte imprimé] / Bassem Andrawes, Auteur ; Reginald DesRoches, Auteur . - 2008 . - pp.173–183. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°2 (Fevrier 2008) . - pp.173–183. Mots-clés : Shape  memory  effect  Elasticity  Earthquakes  Constitutive  models  Seismic  effects  Sensitivity  anlysis. Résumé : Shape memory alloys (SMAs) are known for their superelastic properties, which have been exploited in numerous applications in the biomedical, aerospace, and commercial fields. More recently, these materials have been evaluated for applications in the area of earthquake engineering. One key question that arises when using these materials is the appropriate constitutive material model to use to capture the highly nonlinear behavior of SMAs. This paper explores the effect of using different SMA constitutive models on the resulting response of systems using SMAs. A sensitivity analysis is conducted by using three SMA models with various levels of complexity. The models are implemented in a single-degree-of-freedom system and subjected to three groups of earthquake records with various characteristics. Considering a more accurate trend in modeling incomplete cycles in SMAs has little impact on the structural response. The strength degradation and residual deformation seem to be of more importance than the sublooping behavior. The response is more sensitive to the cyclic effects in the case of records with long durations or large intensities. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A2%2817 [...]