Documents disponibles écrits par cet auteur

Plastic input motion / Elia Voyagaki in Journal of engineering mechanics, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.749–760 Titre : Plastic input motion : Transformation for the response of yielding oscillators Type de document : texte imprimé Auteurs : Elia Voyagaki, Auteur ; Mylonakis, George, Auteur ; Ioannis N. Psycharis, Auteur Année de publication : 2012 Article en page(s) : pp.749–760 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Nonlinear  response  Yielding  oscillator  Scaling  Closed-form  solution  Near-fault  motion  Pulse  Dynamics  Earthquake  response Résumé : A transformation method is presented for the response of yielding oscillators to dynamic loading. The method employs a translation in the ordinates and the abscissa of the excitation function by means of a pair of parameters uniquely dependent on the yielding resistance and the vibrational characteristics of the system. By this approach: (1) the differential operator becomes linearlike, with the nonlinearity transferred to the right-hand side; (2) the initial conditions are simplified; and (3) the modified forcing term becomes uniquely associated with the development of plastic deformation. The theory is applied to various yielding oscillators subjected to idealized earthquake pulses, with the modified excitation function termed plastic input motion (PIM). A procedure for applying the method to general waveforms is provided. The coordinates of PIM may be discontinuous and significantly smaller than those of the original excitation function, as a considerable amount of ground acceleration is devoted to overcoming the elastic resistance of the system. The theory can be useful in earthquake engineering by offering a replacement to physical ground motions with system-dependent PIMs for establishing demand indices. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000373 [article] Plastic input motion : Transformation for the response of yielding oscillators [texte imprimé] / Elia Voyagaki, Auteur ; Mylonakis, George, Auteur ; Ioannis N. Psycharis, Auteur . - 2012 . - pp.749–760. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.749–760 Mots-clés : Nonlinear  response  Yielding  oscillator  Scaling  Closed-form  solution  Near-fault  motion  Pulse  Dynamics  Earthquake  response Résumé : A transformation method is presented for the response of yielding oscillators to dynamic loading. The method employs a translation in the ordinates and the abscissa of the excitation function by means of a pair of parameters uniquely dependent on the yielding resistance and the vibrational characteristics of the system. By this approach: (1) the differential operator becomes linearlike, with the nonlinearity transferred to the right-hand side; (2) the initial conditions are simplified; and (3) the modified forcing term becomes uniquely associated with the development of plastic deformation. The theory is applied to various yielding oscillators subjected to idealized earthquake pulses, with the modified excitation function termed plastic input motion (PIM). A procedure for applying the method to general waveforms is provided. The coordinates of PIM may be discontinuous and significantly smaller than those of the original excitation function, as a considerable amount of ground acceleration is devoted to overcoming the elastic resistance of the system. The theory can be useful in earthquake engineering by offering a replacement to physical ground motions with system-dependent PIMs for establishing demand indices. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000373

Rigid block sliding to idealized acceleration pulses / Voyagaki, Elia in Journal of engineering mechanics, Vol. 138 N° 9 (Septembre 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 9 (Septembre 2012) . - pp.1071–1083. Titre : Rigid block sliding to idealized acceleration pulses Type de document : texte imprimé Auteurs : Voyagaki, Elia, Auteur ; Mylonakis, George, Auteur ; Ioannis N. Psycharis, Auteur Année de publication : 2012 Article en page(s) : pp.1071–1083. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Sliding  Closed-form  solution  Near-fault  Pulse  Asymmetric  friction  Stick-slip  effect Résumé : New analytical solutions are derived for the frictional sliding of rigid blocks to idealized ground acceleration pulses. These excitations are indicative of near-fault earthquake motions affected by forward fault-rupture directivity, which may inflict large permanent displacements in the absence of substantial frictional resistance at the sliding interface. The scope of this study is threefold: (1) to derive analytical solutions for a wide set of idealized pulses; (2) to investigate the effects of symmetric and asymmetric sliding under both unilateral and bilateral excitation conditions; and (3) to explore alternative normalization schemes of peak sliding with reference to peak pulse acceleration, velocity, duration, and shape. A generalized exponential function, capable of simulating an infinite number of pulse waveforms based on a single parameter, is employed to this end. Results are presented in the form of dimensionless closed-form expressions and graphs that provide insight into the physics of the nonlinear problem. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000418 [article] Rigid block sliding to idealized acceleration pulses [texte imprimé] / Voyagaki, Elia, Auteur ; Mylonakis, George, Auteur ; Ioannis N. Psycharis, Auteur . - 2012 . - pp.1071–1083. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 9 (Septembre 2012) . - pp.1071–1083. Mots-clés : Sliding  Closed-form  solution  Near-fault  Pulse  Asymmetric  friction  Stick-slip  effect Résumé : New analytical solutions are derived for the frictional sliding of rigid blocks to idealized ground acceleration pulses. These excitations are indicative of near-fault earthquake motions affected by forward fault-rupture directivity, which may inflict large permanent displacements in the absence of substantial frictional resistance at the sliding interface. The scope of this study is threefold: (1) to derive analytical solutions for a wide set of idealized pulses; (2) to investigate the effects of symmetric and asymmetric sliding under both unilateral and bilateral excitation conditions; and (3) to explore alternative normalization schemes of peak sliding with reference to peak pulse acceleration, velocity, duration, and shape. A generalized exponential function, capable of simulating an infinite number of pulse waveforms based on a single parameter, is employed to this end. Results are presented in the form of dimensionless closed-form expressions and graphs that provide insight into the physics of the nonlinear problem. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000418