Dépouillements

Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections / Hyung-Joon Kim in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 1-21 Titre : Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections Type de document : texte imprimé Auteurs : Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur Article en page(s) : pp. 1-21 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Post-tension;  Self-centering;  Energy  dissipating  devices  ;  Numerical  models;  Flexural  hinges Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : New steel moment-resisting connections that incorporate post-tensioning elements to provide a self-centering capacity and devices to dissipate seismic input energy have recently been proposed and experimentally validated. Experimental studies have confirmed that these connections are capable of undergoing large lateral deformations with negligible residual drifts. To facilitate their implementation, accurate modeling of the behavior of systems incorporating post-tensioned connections must be readily available to designers and researchers. A number of simplified models have been suggested in the literature by researchers trying to capture experimental results at the beam-column connections and thereby to predict the global response of structures incorporating such connections. To provide a clear set of guidelines for the modeling of post-tensioned steel frames, for practicing engineers as well as researchers, in this paper three types of numerical models of increasing complexity are presented: (i) a sectional analysis procedure, (ii) a lumped plasticity spring frame leveled approach and (iii) a non-linear solid finite element analysis to predict the response at ultimate deformation levels. The analytical results obtained from the numerical models predict well the structural behavior of these connections when compared with available experimental data. Even at the ultimate deformation level, analytical results are in good agreement with test results. Furthermore, detailing requirements are proposed to assure that flexural hinges form in the beams in order to improve the cyclic response of steel self-centering connections when drifts exceeding the design drifts are imposed to the system. Experimental and analytical studies demonstrate that steel post-tensioned self-centering connections incorporating the proposed detailing in the beams develop an increased deformation capacity and thereby exhibit a ductile response while avoiding a sudden loss of their strength and stiffness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121356228/abstract [article] Numerical models and ductile ultimate deformation response of post-tensioned self-centering moment connections [texte imprimé] / Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur . - pp. 1-21. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 1-21 Mots-clés : Post-tension;  Self-centering;  Energy  dissipating  devices  ;  Numerical  models;  Flexural  hinges Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : New steel moment-resisting connections that incorporate post-tensioning elements to provide a self-centering capacity and devices to dissipate seismic input energy have recently been proposed and experimentally validated. Experimental studies have confirmed that these connections are capable of undergoing large lateral deformations with negligible residual drifts. To facilitate their implementation, accurate modeling of the behavior of systems incorporating post-tensioned connections must be readily available to designers and researchers. A number of simplified models have been suggested in the literature by researchers trying to capture experimental results at the beam-column connections and thereby to predict the global response of structures incorporating such connections. To provide a clear set of guidelines for the modeling of post-tensioned steel frames, for practicing engineers as well as researchers, in this paper three types of numerical models of increasing complexity are presented: (i) a sectional analysis procedure, (ii) a lumped plasticity spring frame leveled approach and (iii) a non-linear solid finite element analysis to predict the response at ultimate deformation levels. The analytical results obtained from the numerical models predict well the structural behavior of these connections when compared with available experimental data. Even at the ultimate deformation level, analytical results are in good agreement with test results. Furthermore, detailing requirements are proposed to assure that flexural hinges form in the beams in order to improve the cyclic response of steel self-centering connections when drifts exceeding the design drifts are imposed to the system. Experimental and analytical studies demonstrate that steel post-tensioned self-centering connections incorporating the proposed detailing in the beams develop an increased deformation capacity and thereby exhibit a ductile response while avoiding a sudden loss of their strength and stiffness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121356228/abstract

Real-time hybrid testing using the unconditionally stable explicit CR integration algorithm / Cheng Chen in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 23-44 Titre : Real-time hybrid testing using the unconditionally stable explicit CR integration algorithm Type de document : texte imprimé Auteurs : Cheng Chen, Auteur Article en page(s) : pp. 23-44 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Integration  algorithm;  Real-time  hybrid  testing;  Stability  ;  Explicit;  Discrete  transfer  function Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Real-time hybrid testing combines experimental testing and numerical simulation, and provides a viable alternative for the dynamic testing of structural systems. An integration algorithm is used in real-time hybrid testing to compute the structural response based on feedback restoring forces from experimental and analytical substructures. Explicit integration algorithms are usually preferred over implicit algorithms as they do not require iteration and are therefore computationally efficient. The time step size for explicit integration algorithms, which are typically conditionally stable, can be extremely small in order to avoid numerical stability when the number of degree-of-freedom of the structure becomes large. This paper presents the implementation and application of a newly developed unconditionally stable explicit integration algorithm for real-time hybrid testing. The development of the integration algorithm is briefly reviewed. An extrapolation procedure is introduced in the implementation of the algorithm for real-time testing to ensure the continuous movement of the servo-hydraulic actuator. The stability of the implemented integration algorithm is investigated using control theory. Real-time hybrid test results of single-degree-of-freedom and multi-degree-of-freedom structures with a passive elastomeric damper subjected to earthquake ground motion are presented. The explicit integration algorithm is shown to enable the exceptional real-time hybrid test results to be achieved. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/120853924/abstract [article] Real-time hybrid testing using the unconditionally stable explicit CR integration algorithm [texte imprimé] / Cheng Chen, Auteur . - pp. 23-44. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 23-44 Mots-clés : Integration  algorithm;  Real-time  hybrid  testing;  Stability  ;  Explicit;  Discrete  transfer  function Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Real-time hybrid testing combines experimental testing and numerical simulation, and provides a viable alternative for the dynamic testing of structural systems. An integration algorithm is used in real-time hybrid testing to compute the structural response based on feedback restoring forces from experimental and analytical substructures. Explicit integration algorithms are usually preferred over implicit algorithms as they do not require iteration and are therefore computationally efficient. The time step size for explicit integration algorithms, which are typically conditionally stable, can be extremely small in order to avoid numerical stability when the number of degree-of-freedom of the structure becomes large. This paper presents the implementation and application of a newly developed unconditionally stable explicit integration algorithm for real-time hybrid testing. The development of the integration algorithm is briefly reviewed. An extrapolation procedure is introduced in the implementation of the algorithm for real-time testing to ensure the continuous movement of the servo-hydraulic actuator. The stability of the implemented integration algorithm is investigated using control theory. Real-time hybrid test results of single-degree-of-freedom and multi-degree-of-freedom structures with a passive elastomeric damper subjected to earthquake ground motion are presented. The explicit integration algorithm is shown to enable the exceptional real-time hybrid test results to be achieved. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/120853924/abstract

A probabilistic framework for quantification of aftershock ground-motion hazard in California: Methodology and parametric study / Gee Liek Yeo in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 45-60 Titre : A probabilistic framework for quantification of aftershock ground-motion hazard in California: Methodology and parametric study Type de document : texte imprimé Auteurs : Gee Liek Yeo, Auteur ; Allin Cornell, C., Auteur Article en page(s) : pp. 45-60 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Aftershock;  Probabilistic  seismic  hazard  analysis;  Building  tagging Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents a proposed method of aftershock probabilistic seismic hazard analysis (APSHA) similar to conventional mainshock PSHA in that it estimates the likelihoods of ground motion intensity (in terms of peak ground accelerations, spectral accelerations or other ground motion intensity measures) due to aftershocks following a mainshock occurrence. This proposed methodology differs from the conventional mainshock PSHA in that mainshock occurrence rates remain constant for a conventional (homogeneous Poisson) earthquake occurrence model, whereas aftershock occurrence rates decrease with increased elapsed time from the initial occurrence of the mainshock. In addition, the aftershock ground motion hazard at a site depends on the magnitude and location of the causative mainshock, and the location of aftershocks is limited to an aftershock zone, which is also dependent on the location and magnitude of the initial mainshock. APSHA is useful for post-earthquake safety evaluation where there is a need to quantify the rates of occurrence of ground motions caused by aftershocks following the initial rupture. This knowledge will permit, for example, more informed decisions to be made for building tagging and entry of damaged buildings for rescue, repair or normal occupancy. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121378347/abstract [article] A probabilistic framework for quantification of aftershock ground-motion hazard in California: Methodology and parametric study [texte imprimé] / Gee Liek Yeo, Auteur ; Allin Cornell, C., Auteur . - pp. 45-60. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 45-60 Mots-clés : Aftershock;  Probabilistic  seismic  hazard  analysis;  Building  tagging Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents a proposed method of aftershock probabilistic seismic hazard analysis (APSHA) similar to conventional mainshock PSHA in that it estimates the likelihoods of ground motion intensity (in terms of peak ground accelerations, spectral accelerations or other ground motion intensity measures) due to aftershocks following a mainshock occurrence. This proposed methodology differs from the conventional mainshock PSHA in that mainshock occurrence rates remain constant for a conventional (homogeneous Poisson) earthquake occurrence model, whereas aftershock occurrence rates decrease with increased elapsed time from the initial occurrence of the mainshock. In addition, the aftershock ground motion hazard at a site depends on the magnitude and location of the causative mainshock, and the location of aftershocks is limited to an aftershock zone, which is also dependent on the location and magnitude of the initial mainshock. APSHA is useful for post-earthquake safety evaluation where there is a need to quantify the rates of occurrence of ground motions caused by aftershocks following the initial rupture. This knowledge will permit, for example, more informed decisions to be made for building tagging and entry of damaged buildings for rescue, repair or normal occupancy. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121378347/abstract

An innovative methodology for seismic retrofitting of existing RC buildings by metal shear panels / G. De Matteis in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 61-78 Titre : An innovative methodology for seismic retrofitting of existing RC buildings by metal shear panels Type de document : texte imprimé Auteurs : G. De Matteis, Auteur ; A. Formisano, Auteur ; F. M. Mazzolani, Auteur Article en page(s) : pp. 61-78 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Seismic  retrofitting;  RC  buildings;  Metal  shear  panels  ;  Performance-based  seismic  design;  FEM  model Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In the present paper, the seismic upgrading of existing reinforced concrete (RC) structures by means of steel and pure aluminium shear panels is examined. After a preliminary experimental evaluation of the performance of the bare RC structure, a design approach based on the capacity spectrum method has been developed according to the procedure provided in the ATC 40 American guidelines. First, the geometrical configuration of the applied shear panels has been defined according to simplified analytical relationships, while appropriate steel members have been designed to allow the insertion of shear panels in the existing RC structure. Then, complex finite element models have been implemented in order to check the reliability of the proposed design procedure. Also, a numerical evaluation of the global response of the upgraded structure has been processed aiming at evaluating the interaction between the RC structure and the metal devices. Finally, the effectiveness of the applied shear panels has been proven by means of full-scale experimental tests, which confirmed the significant improvement of the RC structure performance, in terms of strength, stiffness and deformation capacity. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121370818/abstract [article] An innovative methodology for seismic retrofitting of existing RC buildings by metal shear panels [texte imprimé] / G. De Matteis, Auteur ; A. Formisano, Auteur ; F. M. Mazzolani, Auteur . - pp. 61-78. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 61-78 Mots-clés : Seismic  retrofitting;  RC  buildings;  Metal  shear  panels  ;  Performance-based  seismic  design;  FEM  model Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In the present paper, the seismic upgrading of existing reinforced concrete (RC) structures by means of steel and pure aluminium shear panels is examined. After a preliminary experimental evaluation of the performance of the bare RC structure, a design approach based on the capacity spectrum method has been developed according to the procedure provided in the ATC 40 American guidelines. First, the geometrical configuration of the applied shear panels has been defined according to simplified analytical relationships, while appropriate steel members have been designed to allow the insertion of shear panels in the existing RC structure. Then, complex finite element models have been implemented in order to check the reliability of the proposed design procedure. Also, a numerical evaluation of the global response of the upgraded structure has been processed aiming at evaluating the interaction between the RC structure and the metal devices. Finally, the effectiveness of the applied shear panels has been proven by means of full-scale experimental tests, which confirmed the significant improvement of the RC structure performance, in terms of strength, stiffness and deformation capacity. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121370818/abstract

Post-quake decision analysis using dynamic programming / Gee Liek Yeo in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 79-93 Titre : Post-quake decision analysis using dynamic programming Type de document : texte imprimé Auteurs : Gee Liek Yeo, Auteur ; Allin Cornell, C., Auteur Article en page(s) : pp. 79-93 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Post-quake;  Aftershock;  Decision  analysis;  Dynamic  programming Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : We introduce a general decision analysis procedure based on stochastic dynamic programming in the post-quake aftershock environment. The damage sustained by the building due to the mainsheet, the time-varying aftershock rates and the potential for further damage progression in the post-quake environment are all factors taken into consideration in the proposed methodology. This procedure enables the optimal decision after the mainshock to be selected based on the minimization of expected financial losses, subject to a constraint on a minimal level of individual life-safety, using a consistent probabilistic framework to explicitly quantify the uncertainties in the variables. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121503004/abstract [article] Post-quake decision analysis using dynamic programming [texte imprimé] / Gee Liek Yeo, Auteur ; Allin Cornell, C., Auteur . - pp. 79-93. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 79-93 Mots-clés : Post-quake;  Aftershock;  Decision  analysis;  Dynamic  programming Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : We introduce a general decision analysis procedure based on stochastic dynamic programming in the post-quake aftershock environment. The damage sustained by the building due to the mainsheet, the time-varying aftershock rates and the potential for further damage progression in the post-quake environment are all factors taken into consideration in the proposed methodology. This procedure enables the optimal decision after the mainshock to be selected based on the minimization of expected financial losses, subject to a constraint on a minimal level of individual life-safety, using a consistent probabilistic framework to explicitly quantify the uncertainties in the variables. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121503004/abstract

Hybrid simulation of a zipper-braced steel frame under earthquake excitation / T. Y. Yang in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 95-113 Titre : Hybrid simulation of a zipper-braced steel frame under earthquake excitation Type de document : texte imprimé Auteurs : T. Y. Yang, Auteur ; B. Stojadinovic, Auteur ; J. Moehle, Auteur Article en page(s) : pp. 95-113 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hybrid  simulation;  Steel  structure;  Steel-braced  frame;  Zipper-braced  frame Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Hybrid simulation is a testing methodology that combines laboratory and analytical simulation to evaluate seismic response of complex structural framing systems. One or more portions of the structure, which may be difficult to model numerically or have properties that have not been examined before, are tested in one or more laboratories, whereas the remainder of the structure is modeled in software using one or more computers. These separate portions are assembled such that combined dynamic response of the hybrid model to excitation is computed using a time-stepping procedure. A hybrid simulation conducted to examine the seismic response of a type of steel concentrically braced frame, the suspended-zipper-braced frame, is presented. The hybrid simulation testing architecture, hybrid model, test setup, solution algorithm, and the seismic response of the suspended-zipper-braced frame hybrid model are discussed. Accuracy of this hybrid simulation is examined by comparing hybrid and computer-only simulations and the errors are quantified using an energy-based approach. This comparison indicates that the deployed hybrid simulation method can be used to accurately model the seismic response of a complex structural system such as the zipper-braced frame. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121412182/abstract [article] Hybrid simulation of a zipper-braced steel frame under earthquake excitation [texte imprimé] / T. Y. Yang, Auteur ; B. Stojadinovic, Auteur ; J. Moehle, Auteur . - pp. 95-113. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 95-113 Mots-clés : Hybrid  simulation;  Steel  structure;  Steel-braced  frame;  Zipper-braced  frame Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Hybrid simulation is a testing methodology that combines laboratory and analytical simulation to evaluate seismic response of complex structural framing systems. One or more portions of the structure, which may be difficult to model numerically or have properties that have not been examined before, are tested in one or more laboratories, whereas the remainder of the structure is modeled in software using one or more computers. These separate portions are assembled such that combined dynamic response of the hybrid model to excitation is computed using a time-stepping procedure. A hybrid simulation conducted to examine the seismic response of a type of steel concentrically braced frame, the suspended-zipper-braced frame, is presented. The hybrid simulation testing architecture, hybrid model, test setup, solution algorithm, and the seismic response of the suspended-zipper-braced frame hybrid model are discussed. Accuracy of this hybrid simulation is examined by comparing hybrid and computer-only simulations and the errors are quantified using an energy-based approach. This comparison indicates that the deployed hybrid simulation method can be used to accurately model the seismic response of a complex structural system such as the zipper-braced frame. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121412182/abstract

A method for estimating specimen tangent stiffness for hybrid simulation / Chung-Chan Hung in Earthquake engineering structural dynamics, Vol. 38 N°1 (Janvier 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 115-134 Titre : A method for estimating specimen tangent stiffness for hybrid simulation Type de document : texte imprimé Auteurs : Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur Article en page(s) : pp. 115-134 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Implicit  methods  ;  Operator-splitting  method;  Accuracy;  Stability Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness matrix of a test specimen in hybrid simulations employing implicit and mixed-integration schemes. However, the computation of the tangent stiffness matrix during testing has proved to be challenging, particularly for test specimens with more than one degree of freedom (dof). This paper presents a new methodology that is more straightforward and simpler than existing techniques for computing the tangent stiffness matrix of a multi-dof test specimen. The proposed method is combined with the operator-splitting method (OSM), and the capabilities, advantages and limitations of the new formulation are demonstrated through several examples. The accuracy, stability, and error propagation characteristics of the modified OSM are also studied theoretically as well as numerically. The research results show that the proposed algorithm provides results that are better than those produced via the regular OSM alone, especially for damped structures undergoing highly inelastic behavior during testing. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121397333/abstract [article] A method for estimating specimen tangent stiffness for hybrid simulation [texte imprimé] / Chung-Chan Hung, Auteur ; Sherif El-Tawil, Auteur . - pp. 115-134. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°1 (Janvier 2009) . - pp. 115-134 Mots-clés : Hybrid  simulation;  Tangent  stiffness;  Implicit  methods  ;  Operator-splitting  method;  Accuracy;  Stability Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness matrix of a test specimen in hybrid simulations employing implicit and mixed-integration schemes. However, the computation of the tangent stiffness matrix during testing has proved to be challenging, particularly for test specimens with more than one degree of freedom (dof). This paper presents a new methodology that is more straightforward and simpler than existing techniques for computing the tangent stiffness matrix of a multi-dof test specimen. The proposed method is combined with the operator-splitting method (OSM), and the capabilities, advantages and limitations of the new formulation are demonstrated through several examples. The accuracy, stability, and error propagation characteristics of the modified OSM are also studied theoretically as well as numerically. The research results show that the proposed algorithm provides results that are better than those produced via the regular OSM alone, especially for damped structures undergoing highly inelastic behavior during testing. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121397333/abstract

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