• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2005.03a
• /
• pp.544-551
• /
• 2005

This paper investigates the effectiveness of the MR damper-based control systems for seismic protection of base isolated building sturcutres employing some semiactive control algorithms, such as the modified clipped-optimal control, the maximum energy dissipation, and the modulated homogeneous friction, by examining the Phase I smart base isolated benchmark building problem. The results of the numerical simulations showed that most of the control systems considered herein could be beneficial in reducing seismic responses, especially base displacement or isolator deformation, of base isolated building structures. It is also verified that another version of the modified clipped-optimal control algorithm proposed in this study and the modulated homogeneous friction algorithm are more effective than other semiactive control algorithms.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.1
• /
• pp.17-29
• /
• 2003

This paper preliminarily investigates the effectiveness of various control systems, such as passive, active, semiactive and hybrid control, for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. This benchm.0.00000ark problem considers the cable-stayed bridge that is scheduled for completion in Missouri, USA In 2003. Seismic considerations were strongly considered in the design of this bridge due to location of the bridge and its critical role as a principal crossing of the Mississippi River. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capability of each control system. In this study, four passive control systems, one active control system, two semiactive control systems and three hybrid control systems are considered. Numerical simulation results show that all the control systems are effective in reducing the responses of the benchmark cable-stayed bridge under the historical earthquakes. To get good performance, however, the passive control systems need quite large control forces compared to other control systems. The simulation results also demonstrate that the passive, semiactive and hybrid control systems are robust to the stiffness uncertainty of the structure. Therefore, the semiactive and hybrid control systems are more appropriate in real applications for full-scale civil infrastructures.

• Wind and Structures
• /
• v.32 no.1
• /
• pp.71-80
• /
• 2021

In steel cable bridges, the use of magnetorheological (MR) dampers between butt cables is constantly increasing to dampen vibrations caused by rain and wind. The biggest problem in the actual applications of those devices is to launch a kind of appropriate algorithm that can effectively and efficiently suppress the perturbation of the tie through basic calculations and optimal solutions. This article discusses the optimal evolutionary design based on a linear and quadratic regulator (hereafter LQR) to lessen the perturbation of the bridges with cables. The control numerical algorithms are expected to effectively and efficiently decrease the possible risks of the structural response in amplification owing to the feedback force in the direction of the MR attenuator. In addition, these numerical algorithms approximate those optimal linear quadratic regulator control forces through the corresponding damping and stiffness, which significantly lessens the work of calculating the significant and optimal control forces. Therefore, it has been shown that it plays an important and significant role in the practical application design of semiactive MR control power systems. In the present proposed novel evolutionary parallel distributed compensator scheme, the vibrational control problem with a simulated demonstration is used to evaluate the numerical algorithmic performance and effectiveness. The results show that these semiactive MR control numerical algorithms which are present proposed in the present paper has better performance than the optimal and the passive control, which is almost reaching the levels of linear quadratic regulator controls with minimal feedback requirements.

• Smart Structures and Systems
• /
• v.23 no.3
• /
• pp.307-318
• /
• 2019

The frequently excessive vibrations presented in civil structures during seismic events or service conditions may result in users' discomfort, or worst, in structures failure, producing economic and even human casualties. This work contributes in proposing the synthesis of a nonlinear optimal control strategy for semiactive structural control, with the main characteristic that the synthesis considers both the structure model and the semiactive actuator nonlinear dynamics, which produces a nonlinear system that requires a nonlinear controller design. The aim is to reduce the unwanted vibrations in the response of civil structures, by means of intelligent fluid semiactive actuator such as the Magnetorheological Damper (MRD), which is a device with a low level of power consumption. The civil structures for which the proposed control methodology can be applied are those admitting a state-dependent coefficient factorized representation model, such as buildings, bridges, among others. A scaled model of a three storey building is analyzed as a case study, whose dynamical response involves displacement, velocity and acceleration of each one of the storeys, subjected to the North-South component of the September 19th., 2017, Puebla-Morelos (7.1M), Mexico earthquake. The investigation rests on comparing the structural response over time for two different conditions: with no control device installed and with one MRD installed between the first floor and the ground, where a nonlinear optimal signal for the MRD input voltage is determined. Simulation results are presented to show the effectiveness of the proposed controller for reducing the building's dynamical response.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.241-245
• /
• 2003

This paper presents the LRB-based hybrid base isolation system employing additional semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal magnetorheological dampers (MRDs) are considered as additional semiactive control devices. Numerical simulation results show that the hybrid base isolation system is effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base Isolation system employing semiactive MRDs is robust to the stiffness uncertainty of the structure. Therefore, the LRB-based hybrid base isolation system employing MRDs could be appropriate in real applications for full-scale civil infrastructures.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.10a
• /
• pp.527-534
• /
• 2003

This paper presents the LRB-based hybrid base isolation systems employing additional active/semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal hydraulic actuators (HAs) and ideal magnetorheological dampers (MRDs) are considered as additional active and semiactive control devices, respectively. Numerical simulation results show that all the hybrid base isolation systems are effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base isolation system employing semiactive MRBs is robust to the stiffness uncertainty of the structure, while the hybrid system with active HAs is not. Therefore, the LRB-based hybrid base isolation system employing MRDs could be more appropriate in real applications for full-scale civil infrastructures.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.10a
• /
• pp.52-59
• /
• 2004

In this paper, the efficacy of the MR damper-based control systems for vibration suppression of stay cables has been experimentally investigated. The performance of the several control strategies for the semiactive control system, such as the clipped-optimal control, the Lyapunov stability theory-based control, the maximum energy dissipation and the modulated homogeneous friction, has been compared with that of the passive-type control systems employing MR dampers. To do this, the full-scale stay cable, which is the same as used for the in-service cable-stayed bridge in Korea, is considered. The acceleration and the displacement of the stay cable as well as the damping force of the MR damper are measured. The velocity of the cable at the damper location, which is needed for some control algorithms, is obtained by differentiating the measured displacement. The damping ratios of the cable system employing the MR damper, which can be estimated by the Hilbert transform-based method, shows effectiveness of each control strategy considered.

• Journal of Institute of Control, Robotics and Systems
• /
• v.4 no.1
• /
• pp.26-31
• /
• 1998

For the semiactive vibration control, a variable damper and proper control systems are essential. In this research, a controllable damper was designed using the MR fluids and its mechanical properties such as damping constant and response time were measured. Since the response time of the MR damper was much longer than nominal MR fluid response time, the time delay of the damper should be considered in the design of controllers. It is shown that the advanced On/Off vibration control which includes the damper time delay performs more effectively than the conventional one.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.8
• /
• pp.160-171
• /
• 1999

The paper examines the ride performance enhancement that can be obtained by applying hydraulic semiactive vibration absorbers(SAVa) to alter the compliance characteristics of the seat/wheel suspension system. The work relies on a consistent model of the (nonlinear) hydrodynamics of the SAVA. A recently developed Lyapunov control scheme is used to provide regulation.. The performance is first examined assuming a quarter car with a seat/seat mounted mass. The paper then employs a quarter car/seat with a two mass ISO model of the seated human . The simulated results indicated that a reduction of 45% of the peak vertical acceleration is achievable with new system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.9 s.180
• /
• pp.2274-2282
• /
• 2000

An MR(Magneto-Rheological) fluid damper is designed and applied to the semi-active suspension system of a 1/4 car model. The damping constant of the MR damper changes according to input current and the time delay of the damper is included in the system dynamics. The passive method, LQ control and Frequency shaped LQ control are compared in experiments. The advantage of the proposed frequency shaped LQ control is that the ride comfort improves in frequency range from 4 to 8Hz where human body is most sensitive and the driving safety improves around the resonance frequency of unsprung mass, 11Hz. The experiments using a 1/4 car model show the effectiveness of the algorithm.