Documents disponibles écrits par cet auteur

Structural behavior of RC beam-column subassemblages under a middle column removal scenario / Yu, Jun in Journal of structural engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 2 (Février 2013) . - pp. 233–250 Titre : Structural behavior of RC beam-column subassemblages under a middle column removal scenario Type de document : texte imprimé Auteurs : Yu, Jun, Auteur ; Kang Hai Tan, Auteur Année de publication : 2013 Article en page(s) : pp. 233–250 Note générale : structural engineering Langues : Anglais (eng) Mots-clés : reinforced  concrete;  beam  columns;  progressive  collapse;  load  factors;  structural  behavior Résumé : Six RC beam-column subassemblages, consisting of two single-bay beams, one middle joint, and two end column stubs, were quasi-statically tested under a middle column removal scenario. The tests were aimed at investigating whether there are alternate load paths that can mitigate progressive collapse. With adequate axial restraints, both compressive arch action (CAA) and catenary action could be mobilized, significantly increasing the structural resistance beyond the beam flexural capacity. The effects of the top and bottom reinforcement ratios at the joint interfaces and beam span-to-depth ratio on structural behavior were studied. The results show that CAA is more beneficial to subassemblages with a short span-to-depth ratio and a low reinforcement ratio, whereas catenary action is more favorable to subassemblages with a large span-to-depth ratio and a high reinforcement ratio, particularly the top reinforcement ratio. As the last defense mechanism to prevent structural collapse, the development of catenary action is highlighted. The onset of catenary action corresponds to the transition of beam axial force from compression to tension, typically occurring at a central deflection around one beam depth in the tests if no shear failure precedes catenary action. At the catenary action stage, prior to fracture of the bottom bars, structural resistance is contributed by both beam axial tension from longitudinal reinforcement and shear force because of dowel action. If the contribution from rising axial tension exceeds the loss as a result of declining shear force, the structural resistance will still keep on increasing until the fracture of the top bars. Finally, the authors suggest a deformation criterion to determine the catenary action of RC subassemblages; i.e., when the deflection at the middle joint attains 10% of the total beam span length, catenary action capacity is reached. The conservatism of this criterion for design purposes is also discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000658 [article] Structural behavior of RC beam-column subassemblages under a middle column removal scenario [texte imprimé] / Yu, Jun, Auteur ; Kang Hai Tan, Auteur . - 2013 . - pp. 233–250. structural engineering Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 2 (Février 2013) . - pp. 233–250 Mots-clés : reinforced  concrete;  beam  columns;  progressive  collapse;  load  factors;  structural  behavior Résumé : Six RC beam-column subassemblages, consisting of two single-bay beams, one middle joint, and two end column stubs, were quasi-statically tested under a middle column removal scenario. The tests were aimed at investigating whether there are alternate load paths that can mitigate progressive collapse. With adequate axial restraints, both compressive arch action (CAA) and catenary action could be mobilized, significantly increasing the structural resistance beyond the beam flexural capacity. The effects of the top and bottom reinforcement ratios at the joint interfaces and beam span-to-depth ratio on structural behavior were studied. The results show that CAA is more beneficial to subassemblages with a short span-to-depth ratio and a low reinforcement ratio, whereas catenary action is more favorable to subassemblages with a large span-to-depth ratio and a high reinforcement ratio, particularly the top reinforcement ratio. As the last defense mechanism to prevent structural collapse, the development of catenary action is highlighted. The onset of catenary action corresponds to the transition of beam axial force from compression to tension, typically occurring at a central deflection around one beam depth in the tests if no shear failure precedes catenary action. At the catenary action stage, prior to fracture of the bottom bars, structural resistance is contributed by both beam axial tension from longitudinal reinforcement and shear force because of dowel action. If the contribution from rising axial tension exceeds the loss as a result of declining shear force, the structural resistance will still keep on increasing until the fracture of the top bars. Finally, the authors suggest a deformation criterion to determine the catenary action of RC subassemblages; i.e., when the deflection at the middle joint attains 10% of the total beam span length, catenary action capacity is reached. The conservatism of this criterion for design purposes is also discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000658

Temperature prediction of concrete-filled rectangular hollow sections in fire using green’s function method / Zhi-Hua Wang in Journal of engineering mechanics, Vol. 133 N°6 (Juin 2007) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 133 N°6 (Juin 2007) . - pp.688–700. Titre : Temperature prediction of concrete-filled rectangular hollow sections in fire using green’s function method Type de document : texte imprimé Auteurs : Zhi-Hua Wang, Auteur ; Kang Hai Tan, Auteur Année de publication : 2007 Article en page(s) : pp.688–700. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Heat  transfer  Greens  function  Fires  Temperature  Predictions Résumé : An efficient numerical approach using the Green’s function solutions of transient heat conduction for predictions of thermal response inside a concrete-filled rectangular hollow section subjected to fire is proposed in this paper. Thermal properties of construction materials are assumed to be isotropic and homogeneous. The Green’s function approach adopts different series expansions for small and large time solutions, therefore the desirable convergence properties can be achieved at any range of time by using the time partitioning strategy. A useful analytical relation in terms of step Green’s functions is derived in this paper to incorporate the multidimensional effect, in particular, for Neumann (prescribed flux) boundary conditions. A modified lumped capacitance method, together with an “orthogonal flux” concept, are employed to deal with spatially varying heat flux at the steel–concrete interface, where Duhamel’s theorem is applied in piecewise manner along the interface to incorporate the fire boundary conditions. No spatial discretization is required in the numerical algorithms based on the Green’s function approach. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A6%2868 [...] [article] Temperature prediction of concrete-filled rectangular hollow sections in fire using green’s function method [texte imprimé] / Zhi-Hua Wang, Auteur ; Kang Hai Tan, Auteur . - 2007 . - pp.688–700. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 133 N°6 (Juin 2007) . - pp.688–700. Mots-clés : Heat  transfer  Greens  function  Fires  Temperature  Predictions Résumé : An efficient numerical approach using the Green’s function solutions of transient heat conduction for predictions of thermal response inside a concrete-filled rectangular hollow section subjected to fire is proposed in this paper. Thermal properties of construction materials are assumed to be isotropic and homogeneous. The Green’s function approach adopts different series expansions for small and large time solutions, therefore the desirable convergence properties can be achieved at any range of time by using the time partitioning strategy. A useful analytical relation in terms of step Green’s functions is derived in this paper to incorporate the multidimensional effect, in particular, for Neumann (prescribed flux) boundary conditions. A modified lumped capacitance method, together with an “orthogonal flux” concept, are employed to deal with spatially varying heat flux at the steel–concrete interface, where Duhamel’s theorem is applied in piecewise manner along the interface to incorporate the fire boundary conditions. No spatial discretization is required in the numerical algorithms based on the Green’s function approach. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A6%2868 [...]