Documents disponibles écrits par cet auteur

Inelastic thermal analysis of preloaded steel trusses undergoing heating and cooling stages / T. J. Lin in Journal of engineering mechanics, Vol. 138 N° 5 (Mai 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 5 (Mai 2012) . - pp.468-477 Titre : Inelastic thermal analysis of preloaded steel trusses undergoing heating and cooling stages Type de document : texte imprimé Auteurs : T. J. Lin, Auteur ; C. W. Huang, Auteur ; Y. B. Yang, Auteur Année de publication : 2012 Article en page(s) : pp.468-477 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Cooling  Heating  Inelastic  thermal  analysis  Steel  truss  Updated  lagrangian  formulation Résumé : The inelastic nonlinear behaviors of preloaded steel trusses undergoing heating and cooling cycles, a problem not well treated previously, are studied in this paper. A bilinear elastoplastic model with a kinematic strain-hardening rule is adopted for steel at varying temperatures. The material softening effects at elevated temperatures are taken into account via the Eurocode 3 reduction factors. The plastic strain resulting from strain reversal upon unloading at a given temperature is considered in updating the stress-strain curve for the next temperature increment. Two simple trusses are adopted to illustrate the physical phenomena involved. All the equations are presented in incremental form, consistent with the updated Lagrangian formulation. The results for the trusses are believed to be new and can be adopted as the benchmarks for validating other numerical approaches used in treating problems involving the heating and cooling stages. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000343 [article] Inelastic thermal analysis of preloaded steel trusses undergoing heating and cooling stages [texte imprimé] / T. J. Lin, Auteur ; C. W. Huang, Auteur ; Y. B. Yang, Auteur . - 2012 . - pp.468-477. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 5 (Mai 2012) . - pp.468-477 Mots-clés : Cooling  Heating  Inelastic  thermal  analysis  Steel  truss  Updated  lagrangian  formulation Résumé : The inelastic nonlinear behaviors of preloaded steel trusses undergoing heating and cooling cycles, a problem not well treated previously, are studied in this paper. A bilinear elastoplastic model with a kinematic strain-hardening rule is adopted for steel at varying temperatures. The material softening effects at elevated temperatures are taken into account via the Eurocode 3 reduction factors. The plastic strain resulting from strain reversal upon unloading at a given temperature is considered in updating the stress-strain curve for the next temperature increment. Two simple trusses are adopted to illustrate the physical phenomena involved. All the equations are presented in incremental form, consistent with the updated Lagrangian formulation. The results for the trusses are believed to be new and can be adopted as the benchmarks for validating other numerical approaches used in treating problems involving the heating and cooling stages. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000343

Soil vibrations caused by underground moving trains / Y. B. Yang in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°11 (Novembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°11 (Novembre 2008) . - pp. 1633–1644 Titre : Soil vibrations caused by underground moving trains Type de document : texte imprimé Auteurs : Y. B. Yang, Auteur ; H. H. Hung, Auteur Année de publication : 2009 Article en page(s) : pp. 1633–1644 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Half  space  Finite  element  method  Railroad  trains  Wave  propagation  Vibration  Tunnels Résumé : The wave propagation problems caused by the underground moving trains are analyzed by the 2.5-dimensional finite/infinite-element approach. The near field of the half-space, including the tunnel and parts of the soil, is simulated by finite elements, and the far field extending to infinity by infinite elements. The train is simulated as a sequence of wheel loads moving at constant speeds. Using the present approach, a two-dimensional profile with three degrees per node is used to simulate the three-dimensional behavior of the half-space, which is valid for the case when the material and geometry of the system are invariant along the tunnel direction. The factors considered in the analysis of ground-borne vibrations include the damping ratio and stratum depth of the supporting soils, the depth and thickness of the tunnel, and the moving speed and excitation frequency of the trains. It was found that moving train loads with nonzero excitation frequencies can induce significantly higher vibrations than the static moving loads. The effect of stratum depth depends highly on the excitation frequency. For a tunnel constructed in a stiffer soil, the ground surface vibrations can be greatly reduced. Other conclusions useful to practical engineers are contained in the parametric study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...] [article] Soil vibrations caused by underground moving trains [texte imprimé] / Y. B. Yang, Auteur ; H. H. Hung, Auteur . - 2009 . - pp. 1633–1644. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°11 (Novembre 2008) . - pp. 1633–1644 Mots-clés : Half  space  Finite  element  method  Railroad  trains  Wave  propagation  Vibration  Tunnels Résumé : The wave propagation problems caused by the underground moving trains are analyzed by the 2.5-dimensional finite/infinite-element approach. The near field of the half-space, including the tunnel and parts of the soil, is simulated by finite elements, and the far field extending to infinity by infinite elements. The train is simulated as a sequence of wheel loads moving at constant speeds. Using the present approach, a two-dimensional profile with three degrees per node is used to simulate the three-dimensional behavior of the half-space, which is valid for the case when the material and geometry of the system are invariant along the tunnel direction. The factors considered in the analysis of ground-borne vibrations include the damping ratio and stratum depth of the supporting soils, the depth and thickness of the tunnel, and the moving speed and excitation frequency of the trains. It was found that moving train loads with nonzero excitation frequencies can induce significantly higher vibrations than the static moving loads. The effect of stratum depth depends highly on the excitation frequency. For a tunnel constructed in a stiffer soil, the ground surface vibrations can be greatly reduced. Other conclusions useful to practical engineers are contained in the parametric study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...]

Thermal effect on the postbuckling behavior of an elastic or elastoplastic truss / Y. B. Yang in Journal of engineering mechanics, Vol. 134 N°4 (Avril 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°4 (Avril 2008) . - pp.330–338. Titre : Thermal effect on the postbuckling behavior of an elastic or elastoplastic truss Type de document : texte imprimé Auteurs : Y. B. Yang, Auteur ; T. J. Lin, Auteur ; Leu, J. M., Auteur Année de publication : 2008 Article en page(s) : pp.330–338. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Bifurcations  Critical  loads  Temperature  Postbuckling  Trusses  Thermal  factors  Elasticity  Elastoplasticity Résumé : Temperature rise may lead to strength degradation and stiffness deterioration of structures under fire conditions. The purpose of this paper is to theoretically study the thermal effect on the postbuckling behavior of an elastic or elastoplastic two-member truss, based on large-deformation elasticity considerations. Two kinds of loadings are considered, i.e., trusses under constant temperature but increasing loads, and trusses under constant loads but rising temperature. For the case with constant temperature, the critical load of an elastic truss will be greatly reduced if the effect of yielding is taken into account. Moreover, yielding of material can cause the truss to bifurcate from the original elastic path. For the case with constant loads, a critical temperature that occurs as the limit point of the temperature–deflection curve can always be found. Besides, the presence of yielding can drastically reduce the critical temperature of an elastic truss, causing it to collapse in an abrupt manner. The solutions presented herein can be used as benchmarks for calibration of the accuracy of general finite-element procedures in analyzing structures under fire conditions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A4%2833 [...] [article] Thermal effect on the postbuckling behavior of an elastic or elastoplastic truss [texte imprimé] / Y. B. Yang, Auteur ; T. J. Lin, Auteur ; Leu, J. M., Auteur . - 2008 . - pp.330–338. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°4 (Avril 2008) . - pp.330–338. Mots-clés : Bifurcations  Critical  loads  Temperature  Postbuckling  Trusses  Thermal  factors  Elasticity  Elastoplasticity Résumé : Temperature rise may lead to strength degradation and stiffness deterioration of structures under fire conditions. The purpose of this paper is to theoretically study the thermal effect on the postbuckling behavior of an elastic or elastoplastic two-member truss, based on large-deformation elasticity considerations. Two kinds of loadings are considered, i.e., trusses under constant temperature but increasing loads, and trusses under constant loads but rising temperature. For the case with constant temperature, the critical load of an elastic truss will be greatly reduced if the effect of yielding is taken into account. Moreover, yielding of material can cause the truss to bifurcate from the original elastic path. For the case with constant loads, a critical temperature that occurs as the limit point of the temperature–deflection curve can always be found. Besides, the presence of yielding can drastically reduce the critical temperature of an elastic truss, causing it to collapse in an abrupt manner. The solutions presented herein can be used as benchmarks for calibration of the accuracy of general finite-element procedures in analyzing structures under fire conditions. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A4%2833 [...]