Documents disponibles écrits par cet auteur

Characterization of a roller seismic isolation bearing with supplemental energy dissipation for highway bridges / George C. Lee in Journal of structural engineering, Vol. 136 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of structural engineering > Vol. 136 N° 5 (Mai 2010) . - pp. 502-510 Titre : Characterization of a roller seismic isolation bearing with supplemental energy dissipation for highway bridges Type de document : texte imprimé Auteurs : George C. Lee, Auteur ; Yu-Chen Ou, Auteur ; Tiecheng Niu, Auteur Année de publication : 2011 Article en page(s) : pp. 502-510 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Seismic  effects  Bridges  Bearings  Isolation  Energy  dissipation  Friction Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A new roller seismic isolation bearing is developed for use in highway bridges. This new bearing uses rolling of cylindrical rollers on V-shaped sloping surfaces to achieve seismic isolation. The bearing is characterized by a constant spectral acceleration under horizontal ground motions and by a self-centering capability, which are two desirable properties for seismic applications. The former makes resonance less likely to occur between the bearing and horizontal earthquakes, while the latter guarantees that the bridge superstructure can self-center to its original position after earthquakes. To provide supplemental energy dissipation to reduce the seismic responses, the bearing is designed with a built-in sliding friction mechanism. This paper presents the seismic behavior of the bearing through analytical and experimental studies. First, the acceleration responses of and forces acting on the bearing under base excitation are presented. Next, the governing equation of horizontal motion, the base shear-horizontal displacement relationship, and conditions for self-centering, for the rollers to maintain contact with the bearing plates, and for rolling without sliding are discussed. An experimental study on a prototype bearing was carried out to verify and calibrate its characteristics and the results are discussed. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i5/p502_s1?isAuthorized=no [article] Characterization of a roller seismic isolation bearing with supplemental energy dissipation for highway bridges [texte imprimé] / George C. Lee, Auteur ; Yu-Chen Ou, Auteur ; Tiecheng Niu, Auteur . - 2011 . - pp. 502-510. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 136 N° 5 (Mai 2010) . - pp. 502-510 Mots-clés : Seismic  effects  Bridges  Bearings  Isolation  Energy  dissipation  Friction Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A new roller seismic isolation bearing is developed for use in highway bridges. This new bearing uses rolling of cylindrical rollers on V-shaped sloping surfaces to achieve seismic isolation. The bearing is characterized by a constant spectral acceleration under horizontal ground motions and by a self-centering capability, which are two desirable properties for seismic applications. The former makes resonance less likely to occur between the bearing and horizontal earthquakes, while the latter guarantees that the bridge superstructure can self-center to its original position after earthquakes. To provide supplemental energy dissipation to reduce the seismic responses, the bearing is designed with a built-in sliding friction mechanism. This paper presents the seismic behavior of the bearing through analytical and experimental studies. First, the acceleration responses of and forces acting on the bearing under base excitation are presented. Next, the governing equation of horizontal motion, the base shear-horizontal displacement relationship, and conditions for self-centering, for the rollers to maintain contact with the bearing plates, and for rolling without sliding are discussed. An experimental study on a prototype bearing was carried out to verify and calibrate its characteristics and the results are discussed. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i5/p502_s1?isAuthorized=no

Large-scale experimental study of precast segmental unbonded posttensioned concrete bridge columns for seismic regions / Yu-Chen Ou in Journal of structural engineering, Vol. 136 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of structural engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 255-264 Titre : Large-scale experimental study of precast segmental unbonded posttensioned concrete bridge columns for seismic regions Type de document : texte imprimé Auteurs : Yu-Chen Ou, Auteur ; Ping-Hsiung Wang, Auteur ; Mu-Sen Tsai, Auteur Année de publication : 2011 Article en page(s) : pp. 255-264 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Substructures  Bridges  Seismic  tests  Precast  concrete  Prestressed  concrete  Concrete  columns  Hollow  sections Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The seismic behavior of the proposed precast segmental unbonded posttensioned concrete bridge columns for use in regions of high seismicity was investigated experimentally. Posttensioning tendons were placed in the hollow core of the columns and left unbonded with the surrounding concrete to decrease prestress loss during earthquakes. Bonded mild steel bars continuous across the segment joints, also referred to as energy dissipation (ED) bars, were used to enhance the seismic resistance of the columns. The bars were unbonded at the critical joint to avoid premature low cycle fatigue failure. The objectives of this study were to (1) verify the proposed construction method and seismic detailing for the ED bars and (2) investigate the seismic behavior of the columns with different ED bar ratios and posttensioning forces. Four large-scale specimens were designed and tested with lateral cyclic loading. Test results showed that the proposed construction method and seismic detailing for the ED bars were effective in ensuring the ductility and ED capability of the bars. The specimens exhibited excellent drift capacities that are adequate for use in regions of high seismicity. The hysteretic ED capacity and residual drift of the column increased as the ED bar contribution to the expected column strength λED increased. To maintain self-centering capability, λED of more than 35% is not recommended. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i3/p255_s1?isAuthorized=no [article] Large-scale experimental study of precast segmental unbonded posttensioned concrete bridge columns for seismic regions [texte imprimé] / Yu-Chen Ou, Auteur ; Ping-Hsiung Wang, Auteur ; Mu-Sen Tsai, Auteur . - 2011 . - pp. 255-264. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 255-264 Mots-clés : Substructures  Bridges  Seismic  tests  Precast  concrete  Prestressed  concrete  Concrete  columns  Hollow  sections Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The seismic behavior of the proposed precast segmental unbonded posttensioned concrete bridge columns for use in regions of high seismicity was investigated experimentally. Posttensioning tendons were placed in the hollow core of the columns and left unbonded with the surrounding concrete to decrease prestress loss during earthquakes. Bonded mild steel bars continuous across the segment joints, also referred to as energy dissipation (ED) bars, were used to enhance the seismic resistance of the columns. The bars were unbonded at the critical joint to avoid premature low cycle fatigue failure. The objectives of this study were to (1) verify the proposed construction method and seismic detailing for the ED bars and (2) investigate the seismic behavior of the columns with different ED bar ratios and posttensioning forces. Four large-scale specimens were designed and tested with lateral cyclic loading. Test results showed that the proposed construction method and seismic detailing for the ED bars were effective in ensuring the ductility and ED capability of the bars. The specimens exhibited excellent drift capacities that are adequate for use in regions of high seismicity. The hysteretic ED capacity and residual drift of the column increased as the ED bar contribution to the expected column strength λED increased. To maintain self-centering capability, λED of more than 35% is not recommended. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v136/i3/p255_s1?isAuthorized=no