The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems....The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems. In this paper, studies of several EMD control strategies and bench-scale shaking table tests of a two-story model structure are described. First, two structural models corresponding to uncontrolled and Zeroed cases are developed, and parameters of these models are validated through sinusoidal sweep tests to provide a basis for establishing an accurate mathematical model for further studies. Then, a simplified control strategy for the EMD system based on the pole assignment control algorithm is proposed. Moreover, ideal pole locations are derived and validated through a series of shaking table tests. Finally, three benchmark earthquake ground motions and sinusoidal sweep waves are imposed onto the structure to investigate the effectiveness and feasibility of using this type of innovative active control system for structural vibration control. In addition, the robustness of the EMD system is examined. The test results show that the EMD system is an effective and robust system for the control of structural vibrations.展开更多
A recently emerging family of smart materials,photostrictive materials,exhibit large photostriction under uniform illumination of high-energy light.This photostriction mechanism arises from a superposition phenomenon ...A recently emerging family of smart materials,photostrictive materials,exhibit large photostriction under uniform illumination of high-energy light.This photostriction mechanism arises from a superposition phenomenon of photovoltaic and converse piezoelectric effects.A photostrictive type of opto-electromechanical actuator activated by high-energy lights can introduce actuation and control effects without hard-wired connections.The control light intensity applied to the actuator is proportional to the transverse velocity at a positioned point,which is measured by a laser vibrometer.In this paper,photostrictive films are numerically analyzed to evaluate their use as wireless actuators for future remote vibration control of flexible structures.A novel opto-electromechanical solid shell finite element formulation is developed for accurate analysis of the multiple physics effects of photovoltaic,pyroelectric and thermal expansion of photostrictive materials.Available experimental data and analytical solutions have been used to verify the present finite element results.The simulation in this study demonstrates that the present formulation is very reliable,accurate and also computationally efficient and that the use of photostrictive actuators can provide good controllability of structural vibration.展开更多
Traditional control strategies have difficulty handling nonlinear behavior of structures, time variable features and parameter uncertainties of structural control systems under seismic excitation. An off-and-towardseq...Traditional control strategies have difficulty handling nonlinear behavior of structures, time variable features and parameter uncertainties of structural control systems under seismic excitation. An off-and-towardsequilibrium （OTE） strategy combined with fuzzy control is presented in this paper to overcome these difficulties. According to the OTE strategy, the control force is designed from the viewpoint of a mechanical relationship between the motions of the structure, the exciting force and the control force. The advantage of the OTE strategy is that it can be used for a variety of control systems. In order to evaluate the performance of the proposed strategy, the seismic performance of a three-story shear building with an Active Tendon System （ATS） using a Fuzzy Logic Controller （FLC） is studied. The main advantage of the fuzzy controller is its inherent robustness and ability to handle any nonlinear behavior of structures. However, there are no design guidelines to set up the corresponding control rule table for a FLC. Based on the proposed strategy for the FLC, a control rule table associated with the building under study is developed, which then allows formation of a detailed algorithm. The results obtained in this study show that the proposed strategy performs slightly better than the linear quadratic regulator （LQR） strategy, while possessing several advantages over the LQR controller. Consequently, the feasibility and validity of the proposed strategy are verified.展开更多
The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation ...The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.展开更多
This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of t...This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.展开更多
Active control technology has been investigated and applied in numerous building structures and infrastructures since 1972 when it was firstly introduced into the civil engineering field by Professor JTP Yao.Now,half ...Active control technology has been investigated and applied in numerous building structures and infrastructures since 1972 when it was firstly introduced into the civil engineering field by Professor JTP Yao.Now,half a century has passed,a variety of control systems have been invented and implemented by researchers and engineers from all over the world.The recent years have witnessed remarkable research attempts and progress devoted to the development in this area based on modern control theory.However,there are still some unknown areas which are worthy of being explored in depth.One of such examples is the application of tuned mass dampers(TMD)to the flutter vibration control of long span bridges.Although applications of TMDs to bridges have been sighted in practice,their genuine effectiveness remains a serious question.The issues relating to how the coupled effect of TMD’s linear force being restricted by the rotational velocity of bridge’s deck during wind excitations which may eventually leads to flutter vibrations,remains unanswered.Such unusual phenomena and limitations were initially discovered and reported by the author sixteen years ago when investigating the barge ship crane hook’s swing motion control.In recent years,the author has invented the active rotary inertia driver(ARID)system which now has been granted patents in China,the US,Europe(including the UK,France,and Germany),Russia,Brazil,India,South Africa,Canada,Australia,Japan and Korean,etc.The ARID is an active control system which could exert direct control torque or moment to the target structures with rotational motions or vibrations natures,including and not limited to buildings,bridges or offshore platforms subjected to winds,earthquakes,and waves excitations.Furthermore,the ARID control system and its methodology can also be applicable to various mechanical systems including but not limited to cranes,vehicles,trains,ships,aircrafts,space crafts,satellites,and robotics.In this paper,the theory,modelling,comprehensive parametric analysis and case study of the ARID system for flutter vibration control of bridges will be discussed,as well as its promising applications in other various occasions.展开更多
The solution to the state response of active constrained layer and the expression of the sound field radiated from the vibrating structure are given, and the damping mechanisms of active constrained layer (ACL) are di...The solution to the state response of active constrained layer and the expression of the sound field radiated from the vibrating structure are given, and the damping mechanisms of active constrained layer (ACL) are discussed. Compaxisons are made with the passive constrained layer (PCL) and the traditional active control method in reducing the structural vibration. The numerical results indicate that: using the active constrained layer damping (ACLD) treatment to dissipate energyt not only the vibration amplitude of structtire is reduced, but also the sound radiated from vibrating structure is suppressed展开更多
Disaster prevention and mitigation for civil engineering structures is an important research field. It involves disaster field forming mechanism, disaster dynamic responses and collapse analysis, disaster prevention a...Disaster prevention and mitigation for civil engineering structures is an important research field. It involves disaster field forming mechanism, disaster dynamic responses and collapse analysis, disaster prevention and mitigation strategies, and so on. The recent researches and applications on disaster prevention and mitigation in civil engineering are commented, especially for the new researches published in Science China.展开更多
基金The National Natural Science Foundation of China Under Grant. No.50608026The National Major Foundamental Program (973 Program) of China Under Grant No. 2007CB714204
文摘The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems. In this paper, studies of several EMD control strategies and bench-scale shaking table tests of a two-story model structure are described. First, two structural models corresponding to uncontrolled and Zeroed cases are developed, and parameters of these models are validated through sinusoidal sweep tests to provide a basis for establishing an accurate mathematical model for further studies. Then, a simplified control strategy for the EMD system based on the pole assignment control algorithm is proposed. Moreover, ideal pole locations are derived and validated through a series of shaking table tests. Finally, three benchmark earthquake ground motions and sinusoidal sweep waves are imposed onto the structure to investigate the effectiveness and feasibility of using this type of innovative active control system for structural vibration control. In addition, the robustness of the EMD system is examined. The test results show that the EMD system is an effective and robust system for the control of structural vibrations.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10872090, 50830201)NUAA Research Funding (Grant No. NJ2010011)
文摘A recently emerging family of smart materials,photostrictive materials,exhibit large photostriction under uniform illumination of high-energy light.This photostriction mechanism arises from a superposition phenomenon of photovoltaic and converse piezoelectric effects.A photostrictive type of opto-electromechanical actuator activated by high-energy lights can introduce actuation and control effects without hard-wired connections.The control light intensity applied to the actuator is proportional to the transverse velocity at a positioned point,which is measured by a laser vibrometer.In this paper,photostrictive films are numerically analyzed to evaluate their use as wireless actuators for future remote vibration control of flexible structures.A novel opto-electromechanical solid shell finite element formulation is developed for accurate analysis of the multiple physics effects of photovoltaic,pyroelectric and thermal expansion of photostrictive materials.Available experimental data and analytical solutions have been used to verify the present finite element results.The simulation in this study demonstrates that the present formulation is very reliable,accurate and also computationally efficient and that the use of photostrictive actuators can provide good controllability of structural vibration.
基金National Natural Science Foundation of China Under Grants No. 50508003 and No.50478042, and A Municipal New Star Plan Program Approved by Beijing Municipal Science & Technology Commission
文摘Traditional control strategies have difficulty handling nonlinear behavior of structures, time variable features and parameter uncertainties of structural control systems under seismic excitation. An off-and-towardsequilibrium （OTE） strategy combined with fuzzy control is presented in this paper to overcome these difficulties. According to the OTE strategy, the control force is designed from the viewpoint of a mechanical relationship between the motions of the structure, the exciting force and the control force. The advantage of the OTE strategy is that it can be used for a variety of control systems. In order to evaluate the performance of the proposed strategy, the seismic performance of a three-story shear building with an Active Tendon System （ATS） using a Fuzzy Logic Controller （FLC） is studied. The main advantage of the fuzzy controller is its inherent robustness and ability to handle any nonlinear behavior of structures. However, there are no design guidelines to set up the corresponding control rule table for a FLC. Based on the proposed strategy for the FLC, a control rule table associated with the building under study is developed, which then allows formation of a detailed algorithm. The results obtained in this study show that the proposed strategy performs slightly better than the linear quadratic regulator （LQR） strategy, while possessing several advantages over the LQR controller. Consequently, the feasibility and validity of the proposed strategy are verified.
基金Project supported by the National Natural Science Foundation of China (No.60034010) the Australia Research Council Discovery-Projects Grant (No.DP0210716)
文摘The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.
文摘This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.
基金supported by the Ministry of Science and Technology of China (Grant No.2019YFE0112400)the Department of Science and Technology of Shandong Province (Grant No.2021CXGC011204)Liaoning Provincial Key Laboratory of Safety and Protection for Infrastructure Engineering。
文摘Active control technology has been investigated and applied in numerous building structures and infrastructures since 1972 when it was firstly introduced into the civil engineering field by Professor JTP Yao.Now,half a century has passed,a variety of control systems have been invented and implemented by researchers and engineers from all over the world.The recent years have witnessed remarkable research attempts and progress devoted to the development in this area based on modern control theory.However,there are still some unknown areas which are worthy of being explored in depth.One of such examples is the application of tuned mass dampers(TMD)to the flutter vibration control of long span bridges.Although applications of TMDs to bridges have been sighted in practice,their genuine effectiveness remains a serious question.The issues relating to how the coupled effect of TMD’s linear force being restricted by the rotational velocity of bridge’s deck during wind excitations which may eventually leads to flutter vibrations,remains unanswered.Such unusual phenomena and limitations were initially discovered and reported by the author sixteen years ago when investigating the barge ship crane hook’s swing motion control.In recent years,the author has invented the active rotary inertia driver(ARID)system which now has been granted patents in China,the US,Europe(including the UK,France,and Germany),Russia,Brazil,India,South Africa,Canada,Australia,Japan and Korean,etc.The ARID is an active control system which could exert direct control torque or moment to the target structures with rotational motions or vibrations natures,including and not limited to buildings,bridges or offshore platforms subjected to winds,earthquakes,and waves excitations.Furthermore,the ARID control system and its methodology can also be applicable to various mechanical systems including but not limited to cranes,vehicles,trains,ships,aircrafts,space crafts,satellites,and robotics.In this paper,the theory,modelling,comprehensive parametric analysis and case study of the ARID system for flutter vibration control of bridges will be discussed,as well as its promising applications in other various occasions.
文摘The solution to the state response of active constrained layer and the expression of the sound field radiated from the vibrating structure are given, and the damping mechanisms of active constrained layer (ACL) are discussed. Compaxisons are made with the passive constrained layer (PCL) and the traditional active control method in reducing the structural vibration. The numerical results indicate that: using the active constrained layer damping (ACLD) treatment to dissipate energyt not only the vibration amplitude of structtire is reduced, but also the sound radiated from vibrating structure is suppressed
文摘Disaster prevention and mitigation for civil engineering structures is an important research field. It involves disaster field forming mechanism, disaster dynamic responses and collapse analysis, disaster prevention and mitigation strategies, and so on. The recent researches and applications on disaster prevention and mitigation in civil engineering are commented, especially for the new researches published in Science China.
