Dépouillements

Dual-plastic hinge design concept for reducing higher-mode effects on high-rise cantilever wall buildings / Panagiotou, Marios in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1359-1380 Titre : Dual-plastic hinge design concept for reducing higher-mode effects on high-rise cantilever wall buildings Type de document : texte imprimé Auteurs : Panagiotou, Marios, Auteur ; Restrepo, José I., Auteur Article en page(s) : pp. 1359-1380 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Capacity  design;  High-rise  buildings;  Higher-mode  effects;  Near-fault  earthquakes;  Plastic  hinges;  Reinforced  concrete;  Seismic  design;  Structural  walls;  Tall  buildings Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper explores the notion of detailing reinforced concrete structural walls to develop base and mid-height plastic hinges to better control the seismic response of tall cantilever wall buildings to strong shaking. This concept, termed here dual-plastic hinge (DPH) concept, is used to reduce the effects of higher modes of response in high-rise buildings. Higher modes can significantly increase the flexural demands in tall cantilever wall buildings. Lumped-mass Euler-Bernoulli cantilevers are used to model the case-study buildings examined in this paper. Buildings with 10, 20 and 40 stories are designed according to three different approaches: ACI-318, Eurocode 8 and the proposed DPH concept. The buildings are designed and subjected to three-specific historical strong near-fault ground motions. The investigation clearly shows the dual-hinge design concept is effective at reducing the effects of the second mode of response. An advantage of the concept is that, when combined with capacity design, it can result in relaxation of special reinforcing detailing in large portions of the walls. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Dual-plastic hinge design concept for reducing higher-mode effects on high-rise cantilever wall buildings [texte imprimé] / Panagiotou, Marios, Auteur ; Restrepo, José I., Auteur . - pp. 1359-1380. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1359-1380 Mots-clés : Capacity  design;  High-rise  buildings;  Higher-mode  effects;  Near-fault  earthquakes;  Plastic  hinges;  Reinforced  concrete;  Seismic  design;  Structural  walls;  Tall  buildings Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper explores the notion of detailing reinforced concrete structural walls to develop base and mid-height plastic hinges to better control the seismic response of tall cantilever wall buildings to strong shaking. This concept, termed here dual-plastic hinge (DPH) concept, is used to reduce the effects of higher modes of response in high-rise buildings. Higher modes can significantly increase the flexural demands in tall cantilever wall buildings. Lumped-mass Euler-Bernoulli cantilevers are used to model the case-study buildings examined in this paper. Buildings with 10, 20 and 40 stories are designed according to three different approaches: ACI-318, Eurocode 8 and the proposed DPH concept. The buildings are designed and subjected to three-specific historical strong near-fault ground motions. The investigation clearly shows the dual-hinge design concept is effective at reducing the effects of the second mode of response. An advantage of the concept is that, when combined with capacity design, it can result in relaxation of special reinforcing detailing in large portions of the walls. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

A substructure shaking table test for reproduction of earthquake responses of high-rise buildings / Ji, Xiaodong in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1381-1399 Titre : A substructure shaking table test for reproduction of earthquake responses of high-rise buildings Type de document : texte imprimé Auteurs : Ji, Xiaodong, Auteur ; Kajiwara, Kouichi, Auteur ; Nagae, Takuya, Auteur ; Ryuta Enokida ; Nakashima, Masayoshi Article en page(s) : pp. 1381-1399 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shaking  table  test;  Substructure;  IDCS  algorithm;  Model  matching  method;  H  method;  high-rise  building Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : When subjected to long-period ground motions, high-rise buildings' upper floors undergo large responses. Furniture and nonstructural components are susceptible to significant damage in such events. This paper proposes a full-scale substructure shaking table test to reproduce large floor responses of high-rise buildings. The response at the top floor of a virtual 30-story building model subjected to a synthesized long-period ground motion is taken as a target wave for reproduction. Since a shaking table has difficulties in directly reproducing such large responses due to various capacity limitations, a rubber-and-mass system is proposed to amplify the table motion. To achieve an accurate reproduction of the floor responses, a control algorithm called the open-loop inverse dynamics compensation via simulation (IDCS) algorithm is used to generate a special input wave for the shaking table. To implement the IDCS algorithm, the model matching method and the H method are adopted to construct the controller. A numerical example is presented to illustrate the open-loop IDCS algorithm and compare the performance of different methods of controller design. A series of full-scale substructure shaking table tests are conducted in E-Defense to verify the effectiveness of the proposed method and examine the seismic behavior of furniture. The test results demonstrate that the rubber-and-mass system is capable of amplifying the table motion by a factor of about 3.5 for the maximum velocity and displacement, and the substructure shaking table test can reproduce the large floor responses for a few minutes ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] A substructure shaking table test for reproduction of earthquake responses of high-rise buildings [texte imprimé] / Ji, Xiaodong, Auteur ; Kajiwara, Kouichi, Auteur ; Nagae, Takuya, Auteur ; Ryuta Enokida ; Nakashima, Masayoshi . - pp. 1381-1399. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1381-1399 Mots-clés : Shaking  table  test;  Substructure;  IDCS  algorithm;  Model  matching  method;  H  method;  high-rise  building Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : When subjected to long-period ground motions, high-rise buildings' upper floors undergo large responses. Furniture and nonstructural components are susceptible to significant damage in such events. This paper proposes a full-scale substructure shaking table test to reproduce large floor responses of high-rise buildings. The response at the top floor of a virtual 30-story building model subjected to a synthesized long-period ground motion is taken as a target wave for reproduction. Since a shaking table has difficulties in directly reproducing such large responses due to various capacity limitations, a rubber-and-mass system is proposed to amplify the table motion. To achieve an accurate reproduction of the floor responses, a control algorithm called the open-loop inverse dynamics compensation via simulation (IDCS) algorithm is used to generate a special input wave for the shaking table. To implement the IDCS algorithm, the model matching method and the H method are adopted to construct the controller. A numerical example is presented to illustrate the open-loop IDCS algorithm and compare the performance of different methods of controller design. A series of full-scale substructure shaking table tests are conducted in E-Defense to verify the effectiveness of the proposed method and examine the seismic behavior of furniture. The test results demonstrate that the rubber-and-mass system is capable of amplifying the table motion by a factor of about 3.5 for the maximum velocity and displacement, and the substructure shaking table test can reproduce the large floor responses for a few minutes ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

Investigation of the sliding behavior between steel and mortar for seismic applications in structures / Jason McCormick in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1401-1419 Titre : Investigation of the sliding behavior between steel and mortar for seismic applications in structures Type de document : texte imprimé Auteurs : Jason McCormick, Auteur ; Nagae, Takuya, Auteur ; Masahiro Ikenaga Article en page(s) : pp. 1401-1419 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Friction;  steel;  Mortar;  Steel  structures;  Shake  table  tests;  Seismic Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The friction developed between a steel base plate and a mortar base contributes shear resistance to the building system during a seismic event. In order to investigate the possible sliding behavior between the base plate and the mortar, a shake table study is undertaken using a large rigid mass supported by steel contact elements which rest on mortar surfaces connected to the shake table. Horizontal input accelerations are considered at various magnitudes and frequencies. The results provide a constant friction coefficient during sliding with an average value of approximately 0.78. A theoretical formulation of the friction behavior is also undertaken. The theoretical equations show that the sliding behavior is dependent on the ratio of the friction force to the input force. The addition of vertical accelerations to the system further complicates the sliding behavior as a result of the varying normal force. This results in a variable friction resistance which is a function of the amplitude, phase, and frequency of the horizontal and vertical input motions. In general, this study showed a consistent and reliable sliding behavior between steel and mortar. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Investigation of the sliding behavior between steel and mortar for seismic applications in structures [texte imprimé] / Jason McCormick, Auteur ; Nagae, Takuya, Auteur ; Masahiro Ikenaga . - pp. 1401-1419. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1401-1419 Mots-clés : Friction;  steel;  Mortar;  Steel  structures;  Shake  table  tests;  Seismic Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The friction developed between a steel base plate and a mortar base contributes shear resistance to the building system during a seismic event. In order to investigate the possible sliding behavior between the base plate and the mortar, a shake table study is undertaken using a large rigid mass supported by steel contact elements which rest on mortar surfaces connected to the shake table. Horizontal input accelerations are considered at various magnitudes and frequencies. The results provide a constant friction coefficient during sliding with an average value of approximately 0.78. A theoretical formulation of the friction behavior is also undertaken. The theoretical equations show that the sliding behavior is dependent on the ratio of the friction force to the input force. The addition of vertical accelerations to the system further complicates the sliding behavior as a result of the varying normal force. This results in a variable friction resistance which is a function of the amplitude, phase, and frequency of the horizontal and vertical input motions. In general, this study showed a consistent and reliable sliding behavior between steel and mortar. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

Torsional balance as new design criterion for asymmetric structures with energy dissipation devices / José L. Almazán in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1421-1440 Titre : Torsional balance as new design criterion for asymmetric structures with energy dissipation devices Type de document : texte imprimé Auteurs : José L. Almazán, Auteur ; Llera (de la), Juan C., Auteur Article en page(s) : pp. 1421-1440 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Torsional  balance;  Plan  asymmetry;  Lateral-torsional  correlation;  Earthquake  response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Lateral-torsional coupling in asymmetric-plan buildings leads to correlated translations and rotations of the building plan, which generate uneven distributions of deformation demand among resisting planes. The deformation demand of a resisting plane depends on the relative magnitude of the plan translation and rotation and on the correlation between the two signals. Thus, small rotations highly correlated with building translation may lead to significantly different deformations of the resisting planes at the building edges. Consequently, the use of supplemental dampers is intended not only to reduce the magnitude of the plan translation and rotation, but also the correlation between these motions. For the sake of simplicity, linear viscous dampers are used in this investigation, which properly located in plan lead to a minimum response of the geometric center, thus achieving the same mean-square value of the displacements at the building edges. Mathematically, this condition may be understood as creating zero correlation between the translations and rotation at the geometric center of the plan, which represents an uncoupling in the mean-square sense. Results show that the optimal damper location depends on the static eccentricity and frequency ratio of the bare structure, the total amount of supplemental damping considered, and the frequency content of the excitation. Through a final 6-story model example, the torsional balance concept is demonstrated to work on multistory buildings subjected to bidirectional ground motions. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Torsional balance as new design criterion for asymmetric structures with energy dissipation devices [texte imprimé] / José L. Almazán, Auteur ; Llera (de la), Juan C., Auteur . - pp. 1421-1440. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1421-1440 Mots-clés : Torsional  balance;  Plan  asymmetry;  Lateral-torsional  correlation;  Earthquake  response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Lateral-torsional coupling in asymmetric-plan buildings leads to correlated translations and rotations of the building plan, which generate uneven distributions of deformation demand among resisting planes. The deformation demand of a resisting plane depends on the relative magnitude of the plan translation and rotation and on the correlation between the two signals. Thus, small rotations highly correlated with building translation may lead to significantly different deformations of the resisting planes at the building edges. Consequently, the use of supplemental dampers is intended not only to reduce the magnitude of the plan translation and rotation, but also the correlation between these motions. For the sake of simplicity, linear viscous dampers are used in this investigation, which properly located in plan lead to a minimum response of the geometric center, thus achieving the same mean-square value of the displacements at the building edges. Mathematically, this condition may be understood as creating zero correlation between the translations and rotation at the geometric center of the plan, which represents an uncoupling in the mean-square sense. Results show that the optimal damper location depends on the static eccentricity and frequency ratio of the bare structure, the total amount of supplemental damping considered, and the frequency content of the excitation. Through a final 6-story model example, the torsional balance concept is demonstrated to work on multistory buildings subjected to bidirectional ground motions. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

Effect of underground cavities on surface earthquake ground motion under SH wave propagation / C. Smerzini in Earthquake engineering structural dynamics, Vol. 38 N° 12 (Octobre 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1441-1460 Titre : Effect of underground cavities on surface earthquake ground motion under SH wave propagation Type de document : texte imprimé Auteurs : C. Smerzini, Auteur ; J. Avilés, Auteur ; R. Paolucci ; Sánchez-Sesma, F. J., Auteur Article en page(s) : pp. 1441-1460 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Analytical  solution  for  SH  wave  propagation;  Underground  cavities;  Rayleigh's  method;  Spectral  amplification  factors Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A theoretical approach is presented to study the antiplane seismic response of underground structures, subjected to the incidence of both plane and cylindrical waves. The structure is assumed to be a circular inclusion embedded in a homogenous, isotropic and linear visco-elastic halfspace. The inclusion may consist either of a cavity, with or without a ring-shaped boundary, or it may be filled in with a linear-elastic material, without loss of generality. The analytical solution is obtained using expansions of wave functions in terms of Bessel and Hankel functions, relying on the technique of images and the use of Graf's addition theorem to enforce the boundary conditions. The effects of underground cavities on surface earthquake ground motion are studied as a function of the size of the cavity, its embedment depth, the frequency content of the excitation, the incidence angle and the distance from the axis of symmetry of the cavity itself. A simple application of Rayleigh's method allows us to verify that the ground surface response is dominated by the fundamental vibration mode of the portion of soil between the cavity and ground surface itself, in the frequency range of interest for engineering purposes. A simple relationship to estimate the fundamental natural frequency as a function of the embedment depth of the cavity is given. Finally, amplification factors on response spectra are obtained, to provide a practical insight into the effect of an underground cavity on surface ground motion during real earthquakes. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Effect of underground cavities on surface earthquake ground motion under SH wave propagation [texte imprimé] / C. Smerzini, Auteur ; J. Avilés, Auteur ; R. Paolucci ; Sánchez-Sesma, F. J., Auteur . - pp. 1441-1460. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 12 (Octobre 2009) . - pp. 1441-1460 Mots-clés : Analytical  solution  for  SH  wave  propagation;  Underground  cavities;  Rayleigh's  method;  Spectral  amplification  factors Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A theoretical approach is presented to study the antiplane seismic response of underground structures, subjected to the incidence of both plane and cylindrical waves. The structure is assumed to be a circular inclusion embedded in a homogenous, isotropic and linear visco-elastic halfspace. The inclusion may consist either of a cavity, with or without a ring-shaped boundary, or it may be filled in with a linear-elastic material, without loss of generality. The analytical solution is obtained using expansions of wave functions in terms of Bessel and Hankel functions, relying on the technique of images and the use of Graf's addition theorem to enforce the boundary conditions. The effects of underground cavities on surface earthquake ground motion are studied as a function of the size of the cavity, its embedment depth, the frequency content of the excitation, the incidence angle and the distance from the axis of symmetry of the cavity itself. A simple application of Rayleigh's method allows us to verify that the ground surface response is dominated by the fundamental vibration mode of the portion of soil between the cavity and ground surface itself, in the frequency range of interest for engineering purposes. A simple relationship to estimate the fundamental natural frequency as a function of the embedment depth of the cavity is given. Finally, amplification factors on response spectra are obtained, to provide a practical insight into the effect of an underground cavity on surface ground motion during real earthquakes. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

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