Documents disponibles écrits par cet auteur

Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses / E. Garini in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 733-756 Titre : Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses Type de document : texte imprimé Auteurs : E. Garini, Auteur ; G. Gazetas, Auteur ; I. Anastasopoulos, Auteur Année de publication : 2011 Article en page(s) : pp. 733-756 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Embankments  Earthquakes  Retaining  walls  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Sliding of a rigid mass supported on an inclined, seismically shaking plane serves as a conceptual and computational model for a variety of problems in geotechnical earthquake engineering. A series of parametric analyses are presented in the paper using as excitation numerous near-fault-recorded severe ground motions and idealised wavelets, bearing the effects of ‘forward-directivity' and ‘fling-step'. Using as key parameters the angle β of the sloping plane (mimicking the sliding surface), as well as the frequency content, intensity, nature and polarity of the excitation, the paper aims at developing a deeper insight into the mechanics of the asymmetric sliding process and the role of key parameters of the excitation. It is shown that ‘directivity' and ‘fling' affected motions containing long-period acceleration pulses and large velocity steps, are particularly ‘destructive' for the examined systems. The amount of accumulating slip on a steep slope is particularly sensitive to reversal of the polarity of excitation. With some special ground motions, in particular (such as the Sakarya and Yarimca accelerograms, both recorded 3 km from the surface expression of the North Anatolian Fault that ruptured in the 1999 Kocaeli earthquake), what might at first glance appear elusively as ‘small details' in the record may turn out to exert a profound influence on the magnitude of slippage – far outweighing the effects of peak acceleration, peak velocity and Arias intensity. The results are compiled in both dimensionless and dimensional charts, and compared with classical charts from the literature. Finally, it is shown that no convincingly robust correlation could exist between accumulated slip and the Arias intensity of excitation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.070 [article] Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses [texte imprimé] / E. Garini, Auteur ; G. Gazetas, Auteur ; I. Anastasopoulos, Auteur . - 2011 . - pp. 733-756. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 733-756 Mots-clés : Embankments  Earthquakes  Retaining  walls  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Sliding of a rigid mass supported on an inclined, seismically shaking plane serves as a conceptual and computational model for a variety of problems in geotechnical earthquake engineering. A series of parametric analyses are presented in the paper using as excitation numerous near-fault-recorded severe ground motions and idealised wavelets, bearing the effects of ‘forward-directivity' and ‘fling-step'. Using as key parameters the angle β of the sloping plane (mimicking the sliding surface), as well as the frequency content, intensity, nature and polarity of the excitation, the paper aims at developing a deeper insight into the mechanics of the asymmetric sliding process and the role of key parameters of the excitation. It is shown that ‘directivity' and ‘fling' affected motions containing long-period acceleration pulses and large velocity steps, are particularly ‘destructive' for the examined systems. The amount of accumulating slip on a steep slope is particularly sensitive to reversal of the polarity of excitation. With some special ground motions, in particular (such as the Sakarya and Yarimca accelerograms, both recorded 3 km from the surface expression of the North Anatolian Fault that ruptured in the 1999 Kocaeli earthquake), what might at first glance appear elusively as ‘small details' in the record may turn out to exert a profound influence on the magnitude of slippage – far outweighing the effects of peak acceleration, peak velocity and Arias intensity. The results are compiled in both dimensionless and dimensional charts, and compared with classical charts from the literature. Finally, it is shown that no convincingly robust correlation could exist between accumulated slip and the Arias intensity of excitation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.070

Effects of near-fault ground shaking on sliding systems / G. Gazetas in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 12 (Décembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1906–1921 Titre : Effects of near-fault ground shaking on sliding systems Type de document : texte imprimé Auteurs : G. Gazetas, Auteur ; E. Garini, Auteur ; I. Anastasopoulos, Auteur Année de publication : 2010 Article en page(s) : pp. 1906–1921 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : SlidingSeismic  effectsGround  motionSymmetryAsymmetry Résumé : A numerical study is presented for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane, and subjected to horizontal or slope-parallel excitation. The latter is described with idealized pulses and near-fault seismic records strongly influenced by forward-directivity or fling-step effects (from Northridge, Kobe, Kocaeli, Chi-Chi, Aegion). In addition to the well known dependence of the resulting block slippage on variables such as the peak base velocity, the peak base acceleration, and the critical acceleration ratio, our study has consistently and repeatedly revealed a profound sensitivity of both maximum and residual slippage: (1) on the sequence and even the details of the pulses contained in the excitation and (2) on the direction ( + or −) in which the shaking of the inclined plane is imposed. By contrast, the slippage is not affected to any measurable degree by even the strongest vertical components of the accelerograms. Moreover, the slippage from a specific record may often be poorly correlated with its Arias intensity. These findings may contradict some of the prevailing beliefs that emanate from statistical correlation studies. The upper-bound sliding displacements from near-fault excitations may substantially exceed the values obtained from some of the currently available design charts. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000174 [article] Effects of near-fault ground shaking on sliding systems [texte imprimé] / G. Gazetas, Auteur ; E. Garini, Auteur ; I. Anastasopoulos, Auteur . - 2010 . - pp. 1906–1921. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1906–1921 Mots-clés : SlidingSeismic  effectsGround  motionSymmetryAsymmetry Résumé : A numerical study is presented for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane, and subjected to horizontal or slope-parallel excitation. The latter is described with idealized pulses and near-fault seismic records strongly influenced by forward-directivity or fling-step effects (from Northridge, Kobe, Kocaeli, Chi-Chi, Aegion). In addition to the well known dependence of the resulting block slippage on variables such as the peak base velocity, the peak base acceleration, and the critical acceleration ratio, our study has consistently and repeatedly revealed a profound sensitivity of both maximum and residual slippage: (1) on the sequence and even the details of the pulses contained in the excitation and (2) on the direction ( + or −) in which the shaking of the inclined plane is imposed. By contrast, the slippage is not affected to any measurable degree by even the strongest vertical components of the accelerograms. Moreover, the slippage from a specific record may often be poorly correlated with its Arias intensity. These findings may contradict some of the prevailing beliefs that emanate from statistical correlation studies. The upper-bound sliding displacements from near-fault excitations may substantially exceed the values obtained from some of the currently available design charts. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000174