Dépouillements

Experimental performance evaluation of an equipment isolation using MR dampers / Yu-Cheng Fan in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 285-305 Titre : Experimental performance evaluation of an equipment isolation using MR dampers Type de document : texte imprimé Auteurs : Yu-Cheng Fan, Auteur ; Chin-Hsiung Loh, Auteur ; Yang, Jann N., Auteur Article en page(s) : pp. 285-305 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Decentralized  control;  Sliding  mode  control;  Equipment  isolation;  MR-damper Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Critical non-structural equipments, including life-saving equipment in hospitals, circuit breakers, computers, high technology instrumentations, etc., are vulnerable to strong earthquakes, and the failure of these equipments may result in a heavy economic loss. In this connection, innovative control systems and strategies are needed for their seismic protections. This paper presents the performance evaluation of passive and semi-active control in the equipment isolation system for earthquake protection. Through shaking table tests of a 3-story steel frame with equipment on the first floor, a magnetorheological (MR)-damper together with a sliding friction pendulum isolation system is placed between the equipment and floor to reduce the vibration of the equipment. Various control algorithms are used for this semi-active control studies, including the decentralized sliding mode control (DSMC) and LQR control. The passive-on and passive-off control of MR damper is used as a reference for the discussion on the control effectiveness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121381101/abstract [article] Experimental performance evaluation of an equipment isolation using MR dampers [texte imprimé] / Yu-Cheng Fan, Auteur ; Chin-Hsiung Loh, Auteur ; Yang, Jann N., Auteur . - pp. 285-305. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 285-305 Mots-clés : Decentralized  control;  Sliding  mode  control;  Equipment  isolation;  MR-damper Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Critical non-structural equipments, including life-saving equipment in hospitals, circuit breakers, computers, high technology instrumentations, etc., are vulnerable to strong earthquakes, and the failure of these equipments may result in a heavy economic loss. In this connection, innovative control systems and strategies are needed for their seismic protections. This paper presents the performance evaluation of passive and semi-active control in the equipment isolation system for earthquake protection. Through shaking table tests of a 3-story steel frame with equipment on the first floor, a magnetorheological (MR)-damper together with a sliding friction pendulum isolation system is placed between the equipment and floor to reduce the vibration of the equipment. Various control algorithms are used for this semi-active control studies, including the decentralized sliding mode control (DSMC) and LQR control. The passive-on and passive-off control of MR damper is used as a reference for the discussion on the control effectiveness. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121381101/abstract

Seismic response of intake towers including dam-tower interaction / M. A. Millán in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 307-329 Titre : Seismic response of intake towers including dam-tower interaction Type de document : texte imprimé Auteurs : M. A. Millán, Auteur ; Y. L. Young, Auteur Article en page(s) : pp. 307-329 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : CE  database  subject  headings:  Intake  structures;  Seismic  analysis;  Dams;  Hydrodynamic  pressures;  Fluid-structure  interaction;  Structural  dynamics Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The seismic response of the intake-outlet towers has been widely analyzed in recent years. The usual models consider the hydrodynamic effects produced by the surrounding water and the interior water, characterizing the dynamic response of the tower-water-foundation-soil system. As a result of these works, simplified added mass models have been developed. However, in all previous models, the surrounding water is assumed to be of uniform depth and to have infinite extension. Consequently, the considered added mass is associated with only the pressures created by the displacements of the tower itself. For a real system, the intake tower is usually located in proximity to the dam and the dam pressures may influence the equivalent added mass. The objective of this paper is to investigate how the response of the tower is affected by the presence of the dam. A coupled three-dimensional boundary element-finite element model in the frequency domain is employed to analyze the tower-dam-reservoir interaction problem. In all cases, the system response is assumed to be linear, and the effect of the internal fluid and the soil-structure interaction effects are not considered. The results suggest that unexpected resonance amplifications can occur due to changes in the added mass for the tower as a result of the tower-dam-reservoir interaction. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121392649/abstract [article] Seismic response of intake towers including dam-tower interaction [texte imprimé] / M. A. Millán, Auteur ; Y. L. Young, Auteur . - pp. 307-329. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 307-329 Mots-clés : CE  database  subject  headings:  Intake  structures;  Seismic  analysis;  Dams;  Hydrodynamic  pressures;  Fluid-structure  interaction;  Structural  dynamics Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The seismic response of the intake-outlet towers has been widely analyzed in recent years. The usual models consider the hydrodynamic effects produced by the surrounding water and the interior water, characterizing the dynamic response of the tower-water-foundation-soil system. As a result of these works, simplified added mass models have been developed. However, in all previous models, the surrounding water is assumed to be of uniform depth and to have infinite extension. Consequently, the considered added mass is associated with only the pressures created by the displacements of the tower itself. For a real system, the intake tower is usually located in proximity to the dam and the dam pressures may influence the equivalent added mass. The objective of this paper is to investigate how the response of the tower is affected by the presence of the dam. A coupled three-dimensional boundary element-finite element model in the frequency domain is employed to analyze the tower-dam-reservoir interaction problem. In all cases, the system response is assumed to be linear, and the effect of the internal fluid and the soil-structure interaction effects are not considered. The results suggest that unexpected resonance amplifications can occur due to changes in the added mass for the tower as a result of the tower-dam-reservoir interaction. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121392649/abstract

Quasi-static and pseudo-dynamic testing of unbonded post-tensioned rocking bridge piers with external replaceable dissipaters / Dion Marriott in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 331-354 Titre : Quasi-static and pseudo-dynamic testing of unbonded post-tensioned rocking bridge piers with external replaceable dissipaters Type de document : texte imprimé Auteurs : Dion Marriott, Auteur ; Pampanin, Stefano, Auteur ; Alessandro Palermo, Auteur Article en page(s) : pp. 331-354 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Bridge  piers;  Unbonded  post-tensioning;  Cyclic  tests;  Pseudo-dynamic;  External  replaceable  dissipaters;  Energy  dissipation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : It has been well documented that following a major earthquake a substantial percentage of economic loss results from downtime of essential lifelines in and out of major urban centres. This has thus led to an improvement of both performance-based seismic design philosophies and to the development of cost-effective seismic structural systems capable of guaranteeing a high level of protection, low structural damage and reduced downtime after a design-level seismic event. An example of such technology is the development of unbonded post-tensioned techniques in combination with rocking-dissipating connections. In this contribution, further advances in the development of high-performance seismic-resistant bridge piers are achieved through the experimental validation of unbonded post-tensioned bridge piers with external, fully replaceable, mild steel hysteretic dissipaters. The experimental response of three 1 : 3 scale unbonded, post-tensioned cantilever bridge piers, subjected to quasi-static and pseudo-dynamic loading protocols, are presented and compared with an equivalently reinforced monolithic benchmark. Minimal physical damage is observed for the post-tensioned systems, which exhibit very stable energy dissipation and re-centring properties. Furthermore, the external dissipaters can be easily replaced if severely damaged under a major (higher than expected) earthquake event. Thus, negligible residual deformations, limited repair costs and downtime can be achieved for critical lifeline components. Satisfactory analytical-experimental comparisons are also presented as a further confirmation of the reliability of the design procedure and of the modelling techniques. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121502265/abstract [article] Quasi-static and pseudo-dynamic testing of unbonded post-tensioned rocking bridge piers with external replaceable dissipaters [texte imprimé] / Dion Marriott, Auteur ; Pampanin, Stefano, Auteur ; Alessandro Palermo, Auteur . - pp. 331-354. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 331-354 Mots-clés : Bridge  piers;  Unbonded  post-tensioning;  Cyclic  tests;  Pseudo-dynamic;  External  replaceable  dissipaters;  Energy  dissipation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : It has been well documented that following a major earthquake a substantial percentage of economic loss results from downtime of essential lifelines in and out of major urban centres. This has thus led to an improvement of both performance-based seismic design philosophies and to the development of cost-effective seismic structural systems capable of guaranteeing a high level of protection, low structural damage and reduced downtime after a design-level seismic event. An example of such technology is the development of unbonded post-tensioned techniques in combination with rocking-dissipating connections. In this contribution, further advances in the development of high-performance seismic-resistant bridge piers are achieved through the experimental validation of unbonded post-tensioned bridge piers with external, fully replaceable, mild steel hysteretic dissipaters. The experimental response of three 1 : 3 scale unbonded, post-tensioned cantilever bridge piers, subjected to quasi-static and pseudo-dynamic loading protocols, are presented and compared with an equivalently reinforced monolithic benchmark. Minimal physical damage is observed for the post-tensioned systems, which exhibit very stable energy dissipation and re-centring properties. Furthermore, the external dissipaters can be easily replaced if severely damaged under a major (higher than expected) earthquake event. Thus, negligible residual deformations, limited repair costs and downtime can be achieved for critical lifeline components. Satisfactory analytical-experimental comparisons are also presented as a further confirmation of the reliability of the design procedure and of the modelling techniques. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121502265/abstract

Seismic design procedure and seismic response of post-tensioned self-centering steel frames / Hyung-Joon Kim in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 355-376 Titre : Seismic design procedure and seismic response of post-tensioned self-centering steel frames Type de document : texte imprimé Auteurs : Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur Article en page(s) : pp. 355-376 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Post-tension;  Self-centering;  Seismic  design  procedure  ;  Restraining  effects Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Post-tensioned (PT) self-centering moment-resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self-centering friction damped (SCFR) moment-resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self-centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment-resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self-centering steel frame system. A six-story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re-designed by the proposed seismic design procedure. Time-history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121461952/abstract [article] Seismic design procedure and seismic response of post-tensioned self-centering steel frames [texte imprimé] / Hyung-Joon Kim, Auteur ; Christopoulos, Constantin, Auteur . - pp. 355-376. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 355-376 Mots-clés : Post-tension;  Self-centering;  Seismic  design  procedure  ;  Restraining  effects Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Post-tensioned (PT) self-centering moment-resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self-centering friction damped (SCFR) moment-resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self-centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment-resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self-centering steel frame system. A six-story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re-designed by the proposed seismic design procedure. Time-history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121461952/abstract

Decentralized Hscrinfin controller design for large-scale civil structures / Yang Wang in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 377-401 Titre : Decentralized Hscrinfin controller design for large-scale civil structures Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Jerome P. Lynch, Auteur ; Kincho H. Law, Auteur Article en page(s) : pp. 377-401 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : H-infinity  control;  Feedback  structural  control;  Decentralized  control;  Smart  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Complexities inherent to large-scale modern civil structures pose many challenges in the design of feedback structural control systems for dynamic response mitigation. With the emergence of low-cost sensors and control devices creating technologies from which large-scale structural control systems can deploy, a future control system may contain hundreds, or even thousands, of such devices. Key issues in such large-scale structural control systems include reduced system reliability, increasing communication requirements, and longer latencies in the feedback loop. To effectively address these issues, decentralized control strategies provide promising solutions that allow control systems to operate at high nodal counts. This paper examines the feasibility of designing a decentralized controller that minimizes the norm of the closed-loop system. control is a natural choice for decentralization because imposition of decentralized architectures is easy to achieve when posing the controller design using linear matrix inequalities. Decentralized control solutions are investigated for both continuous-time and discrete-time formulations. Numerical simulation results using a 3-story and a 20-story structure illustrate the feasibility of the different decentralized control strategies. The results also demonstrate that when realistic semi-active control devices are used in combination with the decentralized control solution, better performance can be gained over the passive control cases. It is shown that decentralized control strategies may provide equivalent or better control performance, given that their centralized counterparts could suffer from longer sampling periods due to communication and computation constraints. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121520796/abstract [article] Decentralized Hscrinfin controller design for large-scale civil structures [texte imprimé] / Yang Wang, Auteur ; Jerome P. Lynch, Auteur ; Kincho H. Law, Auteur . - pp. 377-401. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 377-401 Mots-clés : H-infinity  control;  Feedback  structural  control;  Decentralized  control;  Smart  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Complexities inherent to large-scale modern civil structures pose many challenges in the design of feedback structural control systems for dynamic response mitigation. With the emergence of low-cost sensors and control devices creating technologies from which large-scale structural control systems can deploy, a future control system may contain hundreds, or even thousands, of such devices. Key issues in such large-scale structural control systems include reduced system reliability, increasing communication requirements, and longer latencies in the feedback loop. To effectively address these issues, decentralized control strategies provide promising solutions that allow control systems to operate at high nodal counts. This paper examines the feasibility of designing a decentralized controller that minimizes the norm of the closed-loop system. control is a natural choice for decentralization because imposition of decentralized architectures is easy to achieve when posing the controller design using linear matrix inequalities. Decentralized control solutions are investigated for both continuous-time and discrete-time formulations. Numerical simulation results using a 3-story and a 20-story structure illustrate the feasibility of the different decentralized control strategies. The results also demonstrate that when realistic semi-active control devices are used in combination with the decentralized control solution, better performance can be gained over the passive control cases. It is shown that decentralized control strategies may provide equivalent or better control performance, given that their centralized counterparts could suffer from longer sampling periods due to communication and computation constraints. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121520796/abstract

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