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Jeong-hoi Koo - One of the best experts on this subject based on the ideXlab platform.
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seismic performance evaluation of an mr elastomer Based smart Base Isolation system using real time hybrid simulation
Smart Materials and Structures, 2013Co-Authors: Seunghyun Eem, Hyung-jo Jung, Jeong-hoi KooAbstract:Recently, magneto-rheological (MR) elastomer-Based Base Isolation systems have been actively studied as alternative smart Base Isolation systems because MR elastomers are capable of adjusting their modulus or stiffness depending on the magnitude of the applied magnetic field. By taking advantage of the MR elastomers? stiffness-tuning ability, MR elastomer-Based smart Base Isolation systems strive to alleviate limitations of existing smart Base Isolation systems as well as passive-type Base isolators. Until now, research on MR elastomer-Based Base Isolation systems primarily focused on characterization, design, and numerical evaluations of MR elastomer-Based isolators, as well as experimental tests with simple structure models. However, their applicability to large civil structures has not been properly studied yet because it is quite challenging to numerically emulate the complex behavior of MR elastomer-Based isolators and to conduct experiments with large-size structures. To address these difficulties, this study employs the real-time hybrid simulation technique, which combines physical testing and computational modeling. The primary goal of the current hybrid simulation study is to evaluate seismic performances of an MR elastomer-Based smart Base Isolation system, particularly its adaptability to distinctly different seismic excitations. In the hybrid simulation, a single-story building structure (non-physical, computational model) is coupled with a physical testing setup for a smart Base Isolation system with associated components (such as laminated MR elastomers and electromagnets) installed on a shaking table. A series of hybrid simulations is carried out under two seismic excitations having different dominant frequencies. The results show that the proposed smart Base Isolation system outperforms the passive Base Isolation system in reducing the responses of the structure for the excitations considered in this study.
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Dynamic Analysis of a Smart Base-Isolation System Based on MR Elastomers
ASME 2010 Conference on Smart Materials Adaptive Structures and Intelligent Systems Volume 2, 2010Co-Authors: Hyung-jo Jung, Jeongsu Park, Jeong-hoi KooAbstract:This paper presents a numerical investigation of a smart Base Isolation system employing magneto-rheological (MR) elastomers or an MR elastomer-Based Base Isolation system. MR elastomers are a new class of smart materials whose elastic modulus or stiffness can be adjusted depending on the magnitude of the applied magnetic field. Hence, they can be used as controllable stiffness elements in engineering systems. The primary goal of this study is to investigate the dynamic performance of the smart Base-Isolation in mitigating excessive vibrations of a building structure under earthquake loadings. To this end, a five-story shear building model coupled with a smart Base-Isolation is developed. Using this model, a series of numerical simulations is performed to evaluate the effectiveness of the MR elastomer-Based Base Isolation system under several historic seismic excitations. The results show that the proposed Base Isolation system outperform the conventional passive-type Base Isolation system in reducing the responses of the building structure for all seismic excitations considered in this study.© 2010 ASME
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Numerical investigation of smart Base Isolation system employing MR elastomer
Journal of Physics: Conference Series, 2009Co-Authors: Muhammad Usman, Hyung-jo Jung, S H Sung, D D Jang, Jeong-hoi KooAbstract:This paper evaluates the dynamic performance of a newly proposed smart Base Isolation system employing Magneto-Rheological Elastomers (MREs). MREs belong to a class of smart materials whose elastic modulus or stiffness can be adjusted by varying the magnitude of the magnetic field. The Base Isolation systems are considered as one of the most effective devices for vibration reduction of civil engineering structures in the event of earthquakes. The proposed Base Isolation system strives to enhance the performance of the conventional Base-Isolation system by using controllable MREs. To validate the effectiveness of the MRE-Based Isolation system, an extensive simulation study has been performed using a five degree-of-freedom structure under several historical earthquake excitations. The results show that the proposed system outperformed the conventional system in reducing the responses of the structure in all the seismic excitations considered in the study.
B F Spencer - One of the best experts on this subject based on the ideXlab platform.
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active Base Isolation of buildings subjected to seismic excitations
Earthquake Engineering & Structural Dynamics, 2010Co-Authors: Chiaming Chang, B F SpencerAbstract:Structural control technology has been widely accepted as an effective means for the protection of structures against seismic hazards. Passive Base Isolation is one of the structural control techniques to enhance the performance of structures subjected to severe earthquake excitations. Isolation bearings employed at the Base of a structure naturally increases its flexibility, but concurrently results in large Base displacements. The combination of Base Isolation with active control, i.e. active Base Isolation, creates the possibility of achieving a balanced level of control performance in reductions of either floor accelerations or Base displacements. Many theoretical papers have been written by researchers regarding active Base Isolation. A few experiments have been performed to verify these theories; however, challenges in appropriately scaling the structural system and modeling the complex nature of control-structure interaction (CSI) have limited the applicability of these results. This paper presents the development and experimental verification of an active Base Isolation system for a seismically excited building. First, the general problem formulation and control design procedure are provided. Subsequently, the experimental setup is described; unique features include low-friction pendular bearings and custom-manufactured low-force hydraulic actuators. A new system identification procedure that can effectively capture the phenomena of CSI is then presented and used to realize control-oriented models of the system. H 2 /LQG control strategies employing different performance objectives are developed and experimentally evaluated on a six degree-of-freedom shake table in the Smart Structures Technology Laboratory at the University of Illinois at Urbana-Champaign. The proposed control strategies are shown to perform effectively for a wide range of seismic excitations.
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smart Base Isolation systems
Structures Congress 2000: Advanced Technology in Structural Engineering, 2000Co-Authors: J. C. Ramallo, Erik A. Johnson, B F Spencer, M K SainAbstract:This paper investigates the effectiveness of several Base Isolation strategies for historical earthquakes of various magnitudes and characteristics. The strategies studied herein include Isolation systems with leadrubber bearings and with “smart” (semi-active) dampers. To demonstrate the advantages and disadvantages of the various approaches, historical earthquakes scaled to different magnitudes are used to excite an isolated building structure. Responses examined include: peak Base and structural (relative) displacements, peak Base and structural (absolute) accelerations, and peak applied forces. The adaptable nature of the smart damper system is shown to protect a structure from extreme earthquakes, without sacrificing performance during the more frequent, moderate seismic events.
Hyung-jo Jung - One of the best experts on this subject based on the ideXlab platform.
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seismic performance evaluation of an mr elastomer Based smart Base Isolation system using real time hybrid simulation
Smart Materials and Structures, 2013Co-Authors: Seunghyun Eem, Hyung-jo Jung, Jeong-hoi KooAbstract:Recently, magneto-rheological (MR) elastomer-Based Base Isolation systems have been actively studied as alternative smart Base Isolation systems because MR elastomers are capable of adjusting their modulus or stiffness depending on the magnitude of the applied magnetic field. By taking advantage of the MR elastomers? stiffness-tuning ability, MR elastomer-Based smart Base Isolation systems strive to alleviate limitations of existing smart Base Isolation systems as well as passive-type Base isolators. Until now, research on MR elastomer-Based Base Isolation systems primarily focused on characterization, design, and numerical evaluations of MR elastomer-Based isolators, as well as experimental tests with simple structure models. However, their applicability to large civil structures has not been properly studied yet because it is quite challenging to numerically emulate the complex behavior of MR elastomer-Based isolators and to conduct experiments with large-size structures. To address these difficulties, this study employs the real-time hybrid simulation technique, which combines physical testing and computational modeling. The primary goal of the current hybrid simulation study is to evaluate seismic performances of an MR elastomer-Based smart Base Isolation system, particularly its adaptability to distinctly different seismic excitations. In the hybrid simulation, a single-story building structure (non-physical, computational model) is coupled with a physical testing setup for a smart Base Isolation system with associated components (such as laminated MR elastomers and electromagnets) installed on a shaking table. A series of hybrid simulations is carried out under two seismic excitations having different dominant frequencies. The results show that the proposed smart Base Isolation system outperforms the passive Base Isolation system in reducing the responses of the structure for the excitations considered in this study.
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Dynamic Analysis of a Smart Base-Isolation System Based on MR Elastomers
ASME 2010 Conference on Smart Materials Adaptive Structures and Intelligent Systems Volume 2, 2010Co-Authors: Hyung-jo Jung, Jeongsu Park, Jeong-hoi KooAbstract:This paper presents a numerical investigation of a smart Base Isolation system employing magneto-rheological (MR) elastomers or an MR elastomer-Based Base Isolation system. MR elastomers are a new class of smart materials whose elastic modulus or stiffness can be adjusted depending on the magnitude of the applied magnetic field. Hence, they can be used as controllable stiffness elements in engineering systems. The primary goal of this study is to investigate the dynamic performance of the smart Base-Isolation in mitigating excessive vibrations of a building structure under earthquake loadings. To this end, a five-story shear building model coupled with a smart Base-Isolation is developed. Using this model, a series of numerical simulations is performed to evaluate the effectiveness of the MR elastomer-Based Base Isolation system under several historic seismic excitations. The results show that the proposed Base Isolation system outperform the conventional passive-type Base Isolation system in reducing the responses of the building structure for all seismic excitations considered in this study.© 2010 ASME
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Numerical investigation of smart Base Isolation system employing MR elastomer
Journal of Physics: Conference Series, 2009Co-Authors: Muhammad Usman, Hyung-jo Jung, S H Sung, D D Jang, Jeong-hoi KooAbstract:This paper evaluates the dynamic performance of a newly proposed smart Base Isolation system employing Magneto-Rheological Elastomers (MREs). MREs belong to a class of smart materials whose elastic modulus or stiffness can be adjusted by varying the magnitude of the magnetic field. The Base Isolation systems are considered as one of the most effective devices for vibration reduction of civil engineering structures in the event of earthquakes. The proposed Base Isolation system strives to enhance the performance of the conventional Base-Isolation system by using controllable MREs. To validate the effectiveness of the MRE-Based Isolation system, an extensive simulation study has been performed using a five degree-of-freedom structure under several historical earthquake excitations. The results show that the proposed system outperformed the conventional system in reducing the responses of the structure in all the seismic excitations considered in the study.
J. C. Ramallo - One of the best experts on this subject based on the ideXlab platform.
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“Smart” Base Isolation Strategies Employing Magnetorheological Dampers
Journal of Engineering Mechanics, 2002Co-Authors: H. Yoshioka, J. C. Ramallo, Billie F. SpencerAbstract:One of the most successful means of protecting structures against severe seismic events is Base Isolation. However, optimal design of Base Isolation systems depends on the magnitude of the design level earthquake that is considered. The features of an Isolation system designed for an El Centro-type earthquake typically will not be optimal for a Northridge-type earthquake and vice versa. To be effective during a wide range of seismic events, an Isolation system must be adaptable. To demonstrate the efficacy of recently proposed ''smart'' Base Isolation paradigms, this paper presents the results of an experimental study of a particular adaptable, or smart, Base Isolation system that employs magnetorheological ~MR! dampers. The experimental structure, constructed and tested at the Structural Dynamics and Control/Earthquake Engineering Laboratory at the Univ. of Notre Dame, is a Base-isolated two-degree-of-freedom building model subjected to simulated ground motion. A sponge-type MR damper is installed between the Base and the ground to provide controllable damping for the system. The effectiveness of the proposed smart Base Isolation system is demonstrated for both far-field and near-field earthquake excitations.
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smart Base Isolation systems
Structures Congress 2000: Advanced Technology in Structural Engineering, 2000Co-Authors: J. C. Ramallo, Erik A. Johnson, B F Spencer, M K SainAbstract:This paper investigates the effectiveness of several Base Isolation strategies for historical earthquakes of various magnitudes and characteristics. The strategies studied herein include Isolation systems with leadrubber bearings and with “smart” (semi-active) dampers. To demonstrate the advantages and disadvantages of the various approaches, historical earthquakes scaled to different magnitudes are used to excite an isolated building structure. Responses examined include: peak Base and structural (relative) displacements, peak Base and structural (absolute) accelerations, and peak applied forces. The adaptable nature of the smart damper system is shown to protect a structure from extreme earthquakes, without sacrificing performance during the more frequent, moderate seismic events.
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Semi-active building Base Isolation
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999Co-Authors: J. C. Ramallo, Billie F. Spencer, Erik A. Johnson, Michael K. SainAbstract:Passive Base Isolation systems are one of the most successful and widely implemented technologies for seismic hazard mitigation. However, recent changes to the building codes have made the design requirements such that some of the potential gains of such systems may not be realized. This paper investigates the effects of using controllable semi-active dampers, such as magnetorheological fluid dampers, in a Base Isolation system. A two degree-of-freedom model of a Base isolated building is used, with linear viscous, active, and semi-active supplemental damping devices in the Isolation layer. Using an H/sub 2//LQG control design, semi-active and active devices are able to achieve a notable decrease in Base drifts, compared to the optimal linear passive designs, with no accompanying increase in accelerations imparted into the superstructure.
Seunghyun Eem - One of the best experts on this subject based on the ideXlab platform.
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seismic performance evaluation of an mr elastomer Based smart Base Isolation system using real time hybrid simulation
Smart Materials and Structures, 2013Co-Authors: Seunghyun Eem, Hyung-jo Jung, Jeong-hoi KooAbstract:Recently, magneto-rheological (MR) elastomer-Based Base Isolation systems have been actively studied as alternative smart Base Isolation systems because MR elastomers are capable of adjusting their modulus or stiffness depending on the magnitude of the applied magnetic field. By taking advantage of the MR elastomers? stiffness-tuning ability, MR elastomer-Based smart Base Isolation systems strive to alleviate limitations of existing smart Base Isolation systems as well as passive-type Base isolators. Until now, research on MR elastomer-Based Base Isolation systems primarily focused on characterization, design, and numerical evaluations of MR elastomer-Based isolators, as well as experimental tests with simple structure models. However, their applicability to large civil structures has not been properly studied yet because it is quite challenging to numerically emulate the complex behavior of MR elastomer-Based isolators and to conduct experiments with large-size structures. To address these difficulties, this study employs the real-time hybrid simulation technique, which combines physical testing and computational modeling. The primary goal of the current hybrid simulation study is to evaluate seismic performances of an MR elastomer-Based smart Base Isolation system, particularly its adaptability to distinctly different seismic excitations. In the hybrid simulation, a single-story building structure (non-physical, computational model) is coupled with a physical testing setup for a smart Base Isolation system with associated components (such as laminated MR elastomers and electromagnets) installed on a shaking table. A series of hybrid simulations is carried out under two seismic excitations having different dominant frequencies. The results show that the proposed smart Base Isolation system outperforms the passive Base Isolation system in reducing the responses of the structure for the excitations considered in this study.