The Experts below are selected from a list of 105618 Experts worldwide ranked by ideXlab platform
Masayoshi Nakashima - One of the best experts on this subject based on the ideXlab platform.
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online Hybrid Test on buildings with stud type damper made of slitted steel plates stiffened by wood panels
Procedia Engineering, 2011Co-Authors: Mai Ito, Yosuke Murata, Kazuaki Hoki, Masayoshi NakashimaAbstract:Abstract A new-type hysteretic damper composed of a slitted steel plate and buckling-restraining wood panels is proposed. We conduct online Hybrid Tests of a three story building in which these dampers are installed as stud-type dampers and investigate the validity of design, damping effects, and ultimate behavior of the dampers. The span installing the dampers is Tested physically, while the other backup frames are simulated numerically. The dampers are ductile and stable up to large displacements, since local out-of-plane deformations of the steel plates are reduced and distributed around each slit end equally without concentration. The dampers begin to dissipate energy from a small (0.2%) drift level. More than 80% of total energy exerted in the building is dissipated in the dampers for a serviceability level earthquake, and more than 50% for a safety level earthquake.
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collapse simulation of a four story steel moment frame by a distributed online Hybrid Test
Earthquake Engineering & Structural Dynamics, 2008Co-Authors: Tao Wang, Peng Pan, Jason Mccormick, Nobuya Yoshitake, Yosuke Murata, Masayoshi NakashimaAbstract:The collapse of a one-bay, four-story steel moment frame is simulated in this study by the proposed peer-to-peer (P2P) Internet online Hybrid Test system. The typical beam hinging mechanism, which is ensured by a strong-column, weak-beam design, is reproduced. The plastic hinges at the column bases are taken as the experimental portions, while the superstructure is analyzed numerically by a general-purpose finite element program. The implicit plastic rotations of the two column bases are treated as boundary displacements. In order to account for the complex behavior of the column bases, the P2P system is modified to use the secant stiffness during iterations, and the physical specimens are designed such that the plastic hinge behavior can be obtained. For this study, the three substructures are distributed to different locations. A large ground motion is repeatedly imposed until the column bases lose their capacity to sustain the gravity load. As a result, significant deterioration is observed at both column bases. The proposed P2P system is thus demonstrated to be able to accommodate multiple-Tested substructures involving unstable behavior. The results suggest that the P2P Internet online Hybrid Test system provides a reliable means of studying structures up to collapse. Copyright © 2008 John Wiley & Sons, Ltd.
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on line Hybrid Test combining with general purpose finite element software
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Tao Wang, Masayoshi Nakashima, Peng PanAbstract:A new on-line Hybrid Test system incorporated with the substructuring technique is developed. In this system, a general-purpose finite element software is employed to obtain the restoring forces of the numerical substructure accurately. The restart option is repeatedly used to accommodate the software with alternating loading and analysis characteristic of the on-line Test but without touching the source code. An eight-storey base-isolated structure is Tested to evaluate the feasibility and effectiveness of the proposed Test system. The overall structure is divided into two substructures, i.e. a superstructure to be analysed by the software and a base-isolation layer to be Tested physically. Collisions between the base-isolation layer and the surrounding walls are considered in the Test. The responses of the overall structure are reasonable, and smooth operation is achieved without any malfunction. Copyright © 2006 John Wiley & Sons, Ltd.
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development of peer to peer p2p internet online Hybrid Test system
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Peng Pan, Hiroshi Tomofuji, Tao Wang, Masayoshi Nakashima, Makoto Ohsaki, Khalid M MosalamAbstract:A new Internet online Hybrid Test system, designated the 'peer-to-peer (P2P) Internet online Hybrid Test system', is proposed. In the system, the simulated structure is divided into multiple substructures, and each substructure is analysed numerically or Tested physically in parallel at geographically distributed locations. The equations of motion are not formulated for the entire structure but for each substructure separately. Substructures are treated as highly independent systems, and only standard I/O, i.e. displacements and forces at the boundaries, are used as interfaces. A 'Coordinator' equipped with an iterative algorithm based on quasi-Newton iterations is developed to achieve compatibility and equilibrium at boundaries. A Test procedure, featuring two rounds of quasi-Newton iterations and using assumed elastic stiffness, is adopted to avoid iteration for the substructure being Tested physically. A fast and stable solution using a socket mechanism is developed for data exchange over the Internet. Demonstration Tests applied to a base-isolated structure was conducted, and the results are compared with an online Hybrid Test using the conventional Test method. The results obtained from the P2P Internet Hybrid Test match very closely those obtained from the conventional Tests. Investigations are also carried out on time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests were completed successfully under the constructed Internet online Hybrid Test environment.
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online Hybrid Test by internet linkage of distributed Test analysis domains
Earthquake Engineering & Structural Dynamics, 2005Co-Authors: Peng Pan, Motohide Tada, Masayoshi NakashimaAbstract:Online Hybrid Tests (called the online Tests), particularly when combined with substructuring techniques, are able to conduct large-scale Tests. An extension of this technique is to combine multiple loading Tests conducted in remote locations and to integrate the Tests with large numerical analysis codes. In this study, a new Internet online Test system is developed in which a physical Test is conducted in one place, the associated numerical analysis is performed in a remote location, and the two locations communicate over the Internet. To implement the system, a technique that links Test and analysis domains located at different places is proposed, and an Internet data exchange interface is devised to allow data communication across Internet. A practical method that utilizes standard protocols implemented by operating systems for sharing files and folders is adopted to ensure stable and robust communication between remotely located servers that commonly protect themselves by strict firewalls. To combine the online Test with a finite element program formulated in an incremental form and adopting an implicit integration scheme, a tangent stiffness prediction procedure is proposed. In this procedure, a tangent stiffness is estimated based on a few previous steps of experimental data. Using the system devised, Tests on a base-isolated structure were carried out. Here, the base-isolation layer was taken as the Tested part and Tested in Kyoto University, Japan, and the superstructure was modelled by means of a finite element program and analysed in a computer located in Osaka University. A series of physical Internet online Tests were carried out, with the integration time interval and the method of tangent stiffness prediction as the major parameters. The Tests demonstrated that the Internet communication was very stable and robust, without malfunctions. The proposed method of stiffness prediction was effective even when the experimental hysteresis curves exhibited complex behaviour, thereby ensuring accurate simulation for the earthquake response of the entire structure. Copyright © 2005 John Wiley & Sons, Ltd.
Richard Christenson - One of the best experts on this subject based on the ideXlab platform.
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real time Hybrid Test validation of a mr damper controlled building with shake table Tests
Advances in Structural Engineering, 2011Co-Authors: Yi Zhong Lin, Richard ChristensonAbstract:Real-time Hybrid Testing (RTHTing) is a relatively new form of experimental Testing where only the critical components of the system are physically Tested while the rest of the structure is simulated. A RTHT can provide a cost-effective means for Testing semiactive controlled civil structures. This paper describes the experimental validation of the RTHT facility at the University of Connecticut through comparison of RTHT results with corresponding shake table responses of a Magneto-Rheological (MR) fluid damper controlled Test structure. The two-story structure has an MR damper connected between the ground and first story and is excited by ground accelerations. For the shake table Tests the fully physical building model and MR damper are Tested on a medium-scale shake table. In the RTHT the MR damper alone will be Tested physically while the rest of the Test structure and ground excitation is simulated in the RTHT control computer. The performance of the RTHT is validated by comparing the building respons...
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real time Hybrid simulation using the convolution integral method
Smart Materials and Structures, 2011Co-Authors: Sung Jig Kim, Richard Christenson, Steven F Wojtkiewicz, Erik A JohnsonAbstract:This paper proposes a real-time Hybrid simulation method that will allow complex systems to be Tested within the Hybrid Test framework by employing the convolution integral (CI) method. The proposed CI method is potentially transformative for real-time Hybrid simulation. The CI method can allow real-time Hybrid simulation to be conducted regardless of the size and complexity of the numerical model and for numerical stability to be ensured in the presence of high frequency responses in the simulation. This paper presents the general theory behind the proposed CI method and provides experimental verification of the proposed method by comparing the CI method to the current integration time-stepping (ITS) method. Real-time Hybrid simulation is conducted in the Advanced Hazard Mitigation Laboratory at the University of Connecticut. A seismically excited two-story shear frame building with a magneto-rheological (MR) fluid damper is selected as the Test structure to experimentally validate the proposed method. The building structure is numerically modeled and simulated, while the MR damper is physically Tested. Real-time Hybrid simulation using the proposed CI method is shown to provide accurate results.
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comparison of real time Hybrid Testing with shake table Tests for an mr damper controlled structure
American Control Conference, 2009Co-Authors: Yi Zhong Lin, Richard ChristensonAbstract:This paper compares the results of real-time Hybrid Testing with shake table Tests at the University of Connecticut (UConn) to provide validation of a newly constructed real-time Hybrid Test facility at UConn. The seismic response of a two-story building employing a Magneto-Rheological (MR) fluid damper located between ground and first floor is examined for shake table Testing and real-time Hybrid simulation. For the shake table Tests the two-story building model with Lord Corporation MR Damper (RD-1005-3) is Tested on a medium-scale uniaxial seismic simulator located at UConn. In the real-time Hybrid Test, the building is simulated in a computer while the MR damper is physically Tested in hard real-time. The newly constructed real-time Hybrid Testing facility at UConn provides a means to physically Test critical rate dependant components of structural systems in a state-of-the-art Hybrid simulation facility.
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large scale experimental verification of semiactive control through real time Hybrid simulation
Journal of Structural Engineering-asce, 2008Co-Authors: Richard Christenson, Andrew Emmons, Brent BassAbstract:Magneto-rheological (MR) fluid dampers have been identified as a particularly promising type of semiactive control device for hazard mitigation in civil engineering structures. Large-scale experimental Testing is important to verify the performance of MR fluid dampers for seismic protection of civil structures. Real-time Hybrid Testing, where only the critical components of the system are physically Tested while the rest of the structure is simulated, can provide a cost-effective means for large-scale Testing of semiactive controlled structures. This paper describes the real-time Hybrid simulation experimental setup for multiple large-scale MR fluid dampers and demonstrates the capability at the University of Colorado at Boulder shared-use Fast Hybrid Test facility to conduct real-time Hybrid Testing within the Network for Earthquake Engineering Simulation.
Peng Pan - One of the best experts on this subject based on the ideXlab platform.
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collapse simulation of a four story steel moment frame by a distributed online Hybrid Test
Earthquake Engineering & Structural Dynamics, 2008Co-Authors: Tao Wang, Peng Pan, Jason Mccormick, Nobuya Yoshitake, Yosuke Murata, Masayoshi NakashimaAbstract:The collapse of a one-bay, four-story steel moment frame is simulated in this study by the proposed peer-to-peer (P2P) Internet online Hybrid Test system. The typical beam hinging mechanism, which is ensured by a strong-column, weak-beam design, is reproduced. The plastic hinges at the column bases are taken as the experimental portions, while the superstructure is analyzed numerically by a general-purpose finite element program. The implicit plastic rotations of the two column bases are treated as boundary displacements. In order to account for the complex behavior of the column bases, the P2P system is modified to use the secant stiffness during iterations, and the physical specimens are designed such that the plastic hinge behavior can be obtained. For this study, the three substructures are distributed to different locations. A large ground motion is repeatedly imposed until the column bases lose their capacity to sustain the gravity load. As a result, significant deterioration is observed at both column bases. The proposed P2P system is thus demonstrated to be able to accommodate multiple-Tested substructures involving unstable behavior. The results suggest that the P2P Internet online Hybrid Test system provides a reliable means of studying structures up to collapse. Copyright © 2008 John Wiley & Sons, Ltd.
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on line Hybrid Test combining with general purpose finite element software
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Tao Wang, Masayoshi Nakashima, Peng PanAbstract:A new on-line Hybrid Test system incorporated with the substructuring technique is developed. In this system, a general-purpose finite element software is employed to obtain the restoring forces of the numerical substructure accurately. The restart option is repeatedly used to accommodate the software with alternating loading and analysis characteristic of the on-line Test but without touching the source code. An eight-storey base-isolated structure is Tested to evaluate the feasibility and effectiveness of the proposed Test system. The overall structure is divided into two substructures, i.e. a superstructure to be analysed by the software and a base-isolation layer to be Tested physically. Collisions between the base-isolation layer and the surrounding walls are considered in the Test. The responses of the overall structure are reasonable, and smooth operation is achieved without any malfunction. Copyright © 2006 John Wiley & Sons, Ltd.
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development of peer to peer p2p internet online Hybrid Test system
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Peng Pan, Hiroshi Tomofuji, Tao Wang, Masayoshi Nakashima, Makoto Ohsaki, Khalid M MosalamAbstract:A new Internet online Hybrid Test system, designated the 'peer-to-peer (P2P) Internet online Hybrid Test system', is proposed. In the system, the simulated structure is divided into multiple substructures, and each substructure is analysed numerically or Tested physically in parallel at geographically distributed locations. The equations of motion are not formulated for the entire structure but for each substructure separately. Substructures are treated as highly independent systems, and only standard I/O, i.e. displacements and forces at the boundaries, are used as interfaces. A 'Coordinator' equipped with an iterative algorithm based on quasi-Newton iterations is developed to achieve compatibility and equilibrium at boundaries. A Test procedure, featuring two rounds of quasi-Newton iterations and using assumed elastic stiffness, is adopted to avoid iteration for the substructure being Tested physically. A fast and stable solution using a socket mechanism is developed for data exchange over the Internet. Demonstration Tests applied to a base-isolated structure was conducted, and the results are compared with an online Hybrid Test using the conventional Test method. The results obtained from the P2P Internet Hybrid Test match very closely those obtained from the conventional Tests. Investigations are also carried out on time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests were completed successfully under the constructed Internet online Hybrid Test environment.
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online Hybrid Test by internet linkage of distributed Test analysis domains
Earthquake Engineering & Structural Dynamics, 2005Co-Authors: Peng Pan, Motohide Tada, Masayoshi NakashimaAbstract:Online Hybrid Tests (called the online Tests), particularly when combined with substructuring techniques, are able to conduct large-scale Tests. An extension of this technique is to combine multiple loading Tests conducted in remote locations and to integrate the Tests with large numerical analysis codes. In this study, a new Internet online Test system is developed in which a physical Test is conducted in one place, the associated numerical analysis is performed in a remote location, and the two locations communicate over the Internet. To implement the system, a technique that links Test and analysis domains located at different places is proposed, and an Internet data exchange interface is devised to allow data communication across Internet. A practical method that utilizes standard protocols implemented by operating systems for sharing files and folders is adopted to ensure stable and robust communication between remotely located servers that commonly protect themselves by strict firewalls. To combine the online Test with a finite element program formulated in an incremental form and adopting an implicit integration scheme, a tangent stiffness prediction procedure is proposed. In this procedure, a tangent stiffness is estimated based on a few previous steps of experimental data. Using the system devised, Tests on a base-isolated structure were carried out. Here, the base-isolation layer was taken as the Tested part and Tested in Kyoto University, Japan, and the superstructure was modelled by means of a finite element program and analysed in a computer located in Osaka University. A series of physical Internet online Tests were carried out, with the integration time interval and the method of tangent stiffness prediction as the major parameters. The Tests demonstrated that the Internet communication was very stable and robust, without malfunctions. The proposed method of stiffness prediction was effective even when the experimental hysteresis curves exhibited complex behaviour, thereby ensuring accurate simulation for the earthquake response of the entire structure. Copyright © 2005 John Wiley & Sons, Ltd.
Tao Wang - One of the best experts on this subject based on the ideXlab platform.
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performance evaluation of a distributed Hybrid Test framework to reproduce the collapse behavior of a structure
Earthquake Engineering & Structural Dynamics, 2012Co-Authors: Tao Wang, Gilberto Mosqueda, Andres Jacobsen, Maria CortesdelgadoAbstract:SUMMARY A Hybrid numerical and experimental simulation to collapse was conducted on a one-half scale moment-resisting frame building with two experimental substructures at different locations. An extensible Hybrid Test framework was used that adopts a generalized interface to encapsulate each numerical or Tested substructure, through which only boundary displacements and forces are exchanged. Equilibrium and compatibility between substructures are enforced by an iterative quasi-Newton procedure, while adopting a predictor-and-corrector method to avoid loading reversals on physically Tested substructures. To overcome difficulties in controlling stiff axial and rotational deformations at the boundaries, the flexible Test scheme employs either open-loop or closed-loop control at the boundaries: enforcing either compatibility or equilibrium, or both requirements at critical boundaries. The effectiveness of the extensible framework and its capability to simulate structural behavior through collapse is demonstrated by a geographically distributed Test that reproduced the collapse behavior of a four-story, two-bay, steel moment frame previously Tested on an earthquake simulator. A comparison of both experiments highlights the viability of the Hybrid Test as an effective tool for the performance evaluation of structural systems from the onset of damage through collapse. Copyright © 2011 John Wiley & Sons, Ltd.
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collapse simulation of a four story steel moment frame by a distributed online Hybrid Test
Earthquake Engineering & Structural Dynamics, 2008Co-Authors: Tao Wang, Peng Pan, Jason Mccormick, Nobuya Yoshitake, Yosuke Murata, Masayoshi NakashimaAbstract:The collapse of a one-bay, four-story steel moment frame is simulated in this study by the proposed peer-to-peer (P2P) Internet online Hybrid Test system. The typical beam hinging mechanism, which is ensured by a strong-column, weak-beam design, is reproduced. The plastic hinges at the column bases are taken as the experimental portions, while the superstructure is analyzed numerically by a general-purpose finite element program. The implicit plastic rotations of the two column bases are treated as boundary displacements. In order to account for the complex behavior of the column bases, the P2P system is modified to use the secant stiffness during iterations, and the physical specimens are designed such that the plastic hinge behavior can be obtained. For this study, the three substructures are distributed to different locations. A large ground motion is repeatedly imposed until the column bases lose their capacity to sustain the gravity load. As a result, significant deterioration is observed at both column bases. The proposed P2P system is thus demonstrated to be able to accommodate multiple-Tested substructures involving unstable behavior. The results suggest that the P2P Internet online Hybrid Test system provides a reliable means of studying structures up to collapse. Copyright © 2008 John Wiley & Sons, Ltd.
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on line Hybrid Test combining with general purpose finite element software
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Tao Wang, Masayoshi Nakashima, Peng PanAbstract:A new on-line Hybrid Test system incorporated with the substructuring technique is developed. In this system, a general-purpose finite element software is employed to obtain the restoring forces of the numerical substructure accurately. The restart option is repeatedly used to accommodate the software with alternating loading and analysis characteristic of the on-line Test but without touching the source code. An eight-storey base-isolated structure is Tested to evaluate the feasibility and effectiveness of the proposed Test system. The overall structure is divided into two substructures, i.e. a superstructure to be analysed by the software and a base-isolation layer to be Tested physically. Collisions between the base-isolation layer and the surrounding walls are considered in the Test. The responses of the overall structure are reasonable, and smooth operation is achieved without any malfunction. Copyright © 2006 John Wiley & Sons, Ltd.
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development of peer to peer p2p internet online Hybrid Test system
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Peng Pan, Hiroshi Tomofuji, Tao Wang, Masayoshi Nakashima, Makoto Ohsaki, Khalid M MosalamAbstract:A new Internet online Hybrid Test system, designated the 'peer-to-peer (P2P) Internet online Hybrid Test system', is proposed. In the system, the simulated structure is divided into multiple substructures, and each substructure is analysed numerically or Tested physically in parallel at geographically distributed locations. The equations of motion are not formulated for the entire structure but for each substructure separately. Substructures are treated as highly independent systems, and only standard I/O, i.e. displacements and forces at the boundaries, are used as interfaces. A 'Coordinator' equipped with an iterative algorithm based on quasi-Newton iterations is developed to achieve compatibility and equilibrium at boundaries. A Test procedure, featuring two rounds of quasi-Newton iterations and using assumed elastic stiffness, is adopted to avoid iteration for the substructure being Tested physically. A fast and stable solution using a socket mechanism is developed for data exchange over the Internet. Demonstration Tests applied to a base-isolated structure was conducted, and the results are compared with an online Hybrid Test using the conventional Test method. The results obtained from the P2P Internet Hybrid Test match very closely those obtained from the conventional Tests. Investigations are also carried out on time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests time consumption and control accuracy. The results show that the Internet data exchange solution using the socket mechanism is fast, and Tests were completed successfully under the constructed Internet online Hybrid Test environment.
Pierre Thuriaux - One of the best experts on this subject based on the ideXlab platform.
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the rpb9 subunit of rna polymerase ii binds transcription factor tfiie and interferes with the saga and elongator histone acetyltransferases
Journal of Biological Chemistry, 2002Co-Authors: Vincent Van Mullem, Maxime Wery, Michel Werner, Jean Vandenhaute, Pierre ThuriauxAbstract:Abstract Rpb9 is a small subunit of yeast RNA polymerase II participating in elongation and formed of two conserved zinc domains. rpb9 mutants are viable, with a strong sensitivity to nucleotide-depleting drugs. Deleting the C-terminal domain down to the first 57 amino acids has no detectable growth defect. Thus, the critical part of Rpb9 is limited to a N-terminal half that contacts the lobe of the second largest subunit (Rpb2) and forms a β-addition motif with the “jaw” of the largest subunit (Rpb1). Rpb9 has homology to the TFIIS elongation factor, but mutants inactivated for both proteins are indistinguishable fromrpb9 single mutants. In contrast, rpb9 mutants are lethal in cells lacking the histone acetyltransferase activity of the RNA polymerase II Elongator and SAGA factors. In a two-Hybrid Test, Rpb9 physically interacts with Tfa1, the largest subunit of TFIIE. The interacting fragment, comprising amino acids 62–164 of Tfa1, belongs to a conserved zinc motif. Tfa1 is immunoprecipitated by RNA polymerase II. This co-purification is strongly reduced in rpb9-Δ, suggesting that Rpb9 contributes to the recruitment of TFIIE on RNA polymerase II.
