Semi-active MR Damper Research Articles

Multi-objective control optimization of isolated bridge using replicator controller and NSGA-II

Earthquakes can cause significant damage to constructed structures, leading engineers to design systems that effectively reduce damage and improve real-time vibration control. While base isolation is a commonly used passive method for seismic protection in highway structures, it has limitations such as a lack of immediate adaptation, constrained power dissipation capacity, and poor performance during earthquakes. To address the limitations of passive base isolation bearings, a hybrid control system that includes semi-active MR dampers is being introduced into isolated highway bridge structures. The aim is to enhance vibration reduction and improve overall performance. One of the major challenges in implementing this technology is developing appropriate control algorithms to handle the nonlinear behavior of semi-active devices. This paper proposes an adaptive data-driven control algorithm, informed by evolutionary game theory and a multi-objective optimization process, to optimize the distribution of voltage to semi-active MR dampers based on measurements of the damper's response to input signals. The algorithm is designed to provide optimal seismic protection. The performance of the replicator dynamics in the control system depends on three critical parameters: total population, which represents the total available resources or the sum of actuator forces; growth rate, which is the rate at which resources are distributed among control devices; and the fictitious fitness function, which regulates power consumption. Previous studies used sensitivity analysis to ascertain the best values for population size and growth rate, a time-consuming and unreliable process. This study aims to improve the performance of the system by solving a multi-objective problem. The proposed approach integrates a control algorithm with a multi-objective optimization algorithm, namely NSGA-II, to find Pareto optimal values for all parameters of the replicator dynamics. These parameters include total population, growth rate, and the fictitious function, with the aim of ensuring sustainability. By considering multiple objectives simultaneously, the proposed approach can provide a more comprehensive and effective solution for the bridge control problem. The effectiveness of this proposed approach is demonstrated through sample results Utilizing a case study centered around the Southern California Interstate 91/5 Overcrossing Highway Bridge, which is exposed to seismic activities.

Seismic Response Control for Bridge Piers with Semi-Active MR Damper Based on Displacement Feedback

ABSTRACT This study investigates the semi-active control of railway bridges using an MR damper to reduce the excessive displacement in the bearings of isolated bridges under severe earthquakes. Within the study context, the variable-oval-control (VOC) rule based on structural response displacement feedback is applied to the MR damper and compared with a passive control and clipped optimal semi-active control algorithm. The simulation results show that the dynamic response of railway bridge piers can be effectively reduced, and seismic safety can be significantly improved using MR dampers based on a variable ellipse control strategy. MR damper, based on the VOC rule, directly adopts structural response displacement to perform control force state change. The VOC method only requires the minimum control force to achieve a good displacement control effect, high control efficiency, and stable control effect.

Seismic Fragility Assessment of RC Building Using HAZUS Methodology and Incremental Dynamic Analysis

The technique of coupled building strategy is more viable to protect the adjacent buildings of dissimilar in characteristics against seismic hazards. The philosophy of coupled building control in which adjacent buildings are allowed to exerts counter-acting forces one upon another. This study includes the seismic performance of various Coupled Buildings with respect to Uncoupled Buildings for which two models of Coupled Building are considered that is, first one is the two-shear type adjacent buildings connected in-line with MR dampers and second one is same as first with taller building is isolated by Resilient-Friction Base Isolator at its foundation. The seismic response analysis of RC coupled buildings are studied in terms of peak responses subjected to unidirectional excitation due to Kobe 1995 earthquake. The governing equation of motion of various coupled buildings is solved numerically by Newmark’s step-by-step method. The dynamic behaviour of semiactive MR damper and R-FBI base isolation system has been predicted by modified Bouc-Wen model and Wen’s model respectively. This study employed the Lyapunov direct approach as a control algorithm for the stability analysis and design of semiactive MR controller. The responses of various coupled buildings and uncoupled buildings are simulated through MATLABâ computing software. This study outlined that model of Coupled Building-2 performs more effective in controlling the seismic responses whereas model of Coupled Building-1 performs well not only in reducing the responses but also avoid pounding from the adjacent buildings. Further, there is significant reduction in responses of taller building isolated by base isolation system whereas marginal reduction takes place in shorter building which is not isolated.

Control performance assessment of cable-MR damper system based on pole assignment theory

Semi-active MR dampers have been proposed for cable vibration mitigation of long stay cables, relative theoretical and experimental studies have been carried out in the literature, and have been installed in some of the long span cable-stayed bridges for engineering practice. However, the actual efficiency of the semi-active control of cable-MR damper system has yet to be verified, which is important in real engineering practice. In this paper, the pole assignment theory is used and the corresponding numerical studies is carried out to verify the efficiency of the proposed semi-active control system. The simulation results show that MR damper using semi-active control is more efficient than using passive control and the semi-active control of cable-MR damper system could achieve the optimal control effect and better control efficiency of the system. This paper investigates the efficiency and effectiveness as well as the applicability of the proposed optimal control algorithm using MR damper for mitigating cable vibrations, which is important in real engineering practice.

Comparison of Adaptive magnetorheological elastomer isolator and elastomeric isolator in Near-Field and Far-Field earthquakes

Magnetorheological elastomer (MRE) materials are widely used in the development of smart isolators and absorbers due to their stiffness and damping adaptability. This study investigates the performance of MRE isolators and elastomeric isolators from near-field and far-field earthquakes in benchmark base isolation buildings. All earthquakes are simultaneously applied in two horizontal directions to the horizontal plan. Vertical earthquakes are not attended in the dynamical analysis of benchmark base isolation buildings. For making an isolator model, the effect of bilateral interaction has been considered. The behaviors of MRE isolators and MR dampers are compared. To this end, three control systems including adaptive isolator, passive isolator and semi-active MR damper are considered. The results show that the MRE isolator has a better performance in near-field earthquakes due to its variable stiffness and damping, as compared to the elastomeric isolator. The semi-active MR damper for both far-field and near-field earthquakes has a better control to reduce base displacement, but causes to increase floor accelerations, story drifts and story shear. According to the results of this study, it can be observed that MRE isolator can be used instead of MR damper. The MRE isolator can reduce the base displacement without increasing other responses.

Automotive vehicle engine mount based on an MR squeeze-mode damper: modeling and simulation

The study investigates the performance of a semi-active vehicle engine mount incorporating an MR damper working in the squeeze mode (MRSQD), summarising its design, operating principles and key characteristics. The mathematical model of the mount is formulated based on the newly developed MRSQD. Two control algorithms are proposed for MRSQD control. The first algorithm (ALG1) uses the inverse model of the engine-frame system, the other is the sliding mode algorithm (ALG2). The effectiveness of the engine mount system is demonstrated in computer simulation.

Application of simple adaptive control to an MR damper-based control system for seismically excited nonlinear buildings

In this paper, Simple Adaptive Control (SAC) is used to enhance the seismic response of nonlinear tall buildings based on acceleration feedback. Semi-active MR dampers are employed as control actuator due to their reliability and well-known dynamic models. Acceleration feedback is used because of availability, cost-efficiency and reliable measurements of acceleration sensors. However, using acceleration feedback in the control loop causes the structure not to apparently meet some requirements of the SAC algorithm. In addition to defining an appropriate SAC reference model and using inherently stable MR dampers, a modification in the original structure of the SAC is proposed in order to improve its adaptability to the situation in which the plant does not satisfy the algorithm\' s stability requirements. To investigate the performance of the developed control system, a numerical study is conducted on the benchmark 20-story nonlinear building and the responses of the SAC-controlled structure are compared to an H2/LQG clipped-optimal controller under the effect of different seismic excitations. As indicated by the results, SAC controller effectively reduces the story drifts and hence the seismically-induced damage throughout the structural members despite its simplicity, independence of structural parameters and while using fewer number of dampers in contrast with the H2/LQG clipped-optimal controller.

Real-time Semi-active Vibration Control in Cable-stayed Bridges by Shear-type MR damper and Clipped-optimal Control Algorithm

This paper is concerned with an experimental research to control of random vibration caused by external loads specially in cable-stayed bridges which tend to be structurally flexible. For the vibration control, we produced a model structure modelled on Seohae Grand Bridge, and we designed a shear type MR damper. On the center of its middle span, we placed a shear type MR damper which was to control its vibration and also acquire its structural responses such as displacement and acceleration at the same site. The experiments concerning controlling vibration were performed according to a variety of theories including un-control, passive on/off control, and clipped-optimal control. Its control performance was evaluated in terms of the absolute maximum displacements, RMS displacements, the absolute maximum accelerations, RMS accelerations, and the total power required to control the bridge which differ from each different experiment method. Among all the methods applied in this paper, clipped-optimal control method turned out to be the most effective to reduces of displacements, accelerations, and external power. Finally, It is proven that the clipped-optimal control method was effective and useful in the vibration control employing a semi-active devices such MR damper.

Shaking table testing of a steel frame structure equipped with semi-active MR dampers: comparison of control algorithms

The effectiveness of the various control algorithms for semi-active structural control systems proposed in the literature is highly questionable when dealing with earthquake actions, which never reach a steady state. From this perspective, the paper summarizes the results of an experimental activity aimed to compare the effectiveness of four different semi-active control algorithms on a structural mock up representative of a class of structural systems particularly prone to seismic actions. The controlled structure is a near full scale 2-story steel frame, equipped with two semi-active bracing systems including two magnetorheological dampers designed and manufactured in Europe. A set of earthquake records has been applied at the base of the structure, by utilizing a shaking table facility. Experimental results are compared in terms of displacements, absolute accelerations and energy dissipation capability. A further analysis on the percentage incidence of undesired and/or unpredictable operations corresponding to each algorithm gives an insight on some factors affecting the reliability and, in turn, the real effectiveness of semi-active structural control systems.

MR 댐퍼가 적용된 철도차량 이차현가장치의 H∞제어

In general, lateral ride comfort of railway vehicle is mainly influenced by a secondary suspension placed between the bogie and carbody. Higher operating speeds of train results in increased vibration of carbody, which has a negative impact related to the ride comfort. To solve this problem, researches to replace the conventional passive suspension with (semi)active technology in the secondary suspension of a railway vehicle have been carried out. The semi-active suspension using the magneto-rheological damper is relatively simpler system and has advantage in maintenance compared to the hydraulic type semi-active damper. This study was performed to reduce lateral vibration acceleration of carbody related to ride comfort of railway vehicles with a semi-active suspension system. The numerical analysis was conducted by replacing passive lateral damper with semi-active MR damper, and robust control with the MR damper was applied to the 1/5 scaled railway vehicle model.

Shaking table experimentation on adjacent structures controlled by passive and semi-active MR dampers

This paper presents the results of shaking table tests on adjacent structures controlled by passive and semi-active MR dampers. The aim was to demonstrate experimentally the effectiveness of passive and semi-active strategies in reducing structural vibrations due to seismic excitation. The physical model at issue was represented by two adjacent steel structures, respectively of 4 and 2 levels, connected at the second level by a MR damper. When the device operated in semi-active mode, an ON–OFF control algorithm, derived by the Lyapunov stability theory, was implemented and experimentally validated. Since the experimentation concerned adjacent structures, two control objectives have been reached: global and selective protection. In case of global protection, the attention was focused on protecting both structures, whereas, in case of selective protection, the attention was focused on protecting only one structure. For each objective the effectiveness of passive control has been compared with the situation of no control and then the effectiveness of semi-active control has been compared with the passive one. The quantities directly compared have been: measured displacements, accelerations and force–displacement of the MR damper, moreover some global response quantities have been estimated from experimental measures, which are the base share force and the base bending moment, the input energy and the energy dissipated by the device. In order to evaluate the effectiveness of the control action in both passive and semi-active case, an energy index EDI, previously defined and already often applied numerically, has been utilized. The aspects investigated in the experimentation have been: the implementation and validation of the control algorithm for selective and global protection, the MR damper input voltage influence, the kind of seismic input and its intensity.

Vibration mitigation of stay cable using optimally tuned MR damper

Mechanical dampers have been proved to be one of the most effective countermeasures for vibration mitigation of stay cables in various cable-stayed bridges over the world. However, for long stay cables, as the installation height of the damper is restricted due to the aesthetic concern, using passive dampers alone may not satisfy the control requirement of the stay cables. In this connection, semi-active MR dampers have been proposed for the vibration mitigation of long stay cables. Although various studies have been carried out on the implementation of MR dampers on stay cables, the optimal damping performance of the cable-MR damper system has yet to be evaluated. Therefore, this paper aims to investigate the effectiveness of MR damper as a semi-active control device for the vibration mitigation of stay cable. The mathematical model of the MR damper will first be established through a performance test. Then, an efficient semi-active control strategy will be derived, where the damping of MR damper will be tuned according to the dynamic characteristics of stay cable, in order to achieve optimal damping of cable-damper system. Simulation study will be carried out to verify the proposed semi-active control algorithm for suppressing the cable vibrations induced by different loading patterns using optimally tuned MR damper. Finally, the effectiveness of MR damper in mitigating multi modes of cable vibration will be examined theoretically.

Vibration mitigation of stay cable using optimally tuned MR damper

Mechanical dampers have been proved to be one of the most effective countermeasures for vibration mitigation of stay cables in various cable-stayed bridges over the world. However, for long stay cables, as the installation height of the damper is restricted due to the aesthetic concern, using passive dampers alone may not satisfy the control requirement of the stay cables. In this connection, semi-active MR dampers have been proposed for the vibration mitigation of long stay cables. Although various studies have been carried out on the implementation of MR dampers on stay cables, the optimal damping performance of the cable-MR damper system has yet to be evaluated. Therefore, this paper aims to investigate the effectiveness of MR damper as a semi-active control device for the vibration mitigation of stay cable. The mathematical model of the MR damper will first be established through a performance test. Then, an efficient semi-active control strategy will be derived, where the damping of MR damper will be tuned according to the dynamic characteristics of stay cable, in order to achieve optimal damping of cable-damper system. Simulation study will be carried out to verify the proposed semi-active control algorithm for suppressing the cable vibrations induced by different loading patterns using optimally tuned MR damper. Finally, the effectiveness of MR damper in mitigating multi modes of cable vibration will be examined theoretically

A decentralized response-dependent MR damper for controlling building structures excited by seismic load

In this study, a decentralized algorithm for operating a semiactive MR damper was presented. The frictional force of the MR damper was determined based on the assumed shape functions using the displacement and velocity of the damper piston itself. The seismic response control performance of the MR damper was numerically and experimentally evaluated and compared to that of the passively or semiactively operated MR damper. The results from numerical analysis of SDOF system indicated that passively operated MR damper to have an optimal frictional force less than about 30% of the base shear force provided the smallest displacement response spectrum over all the periods. The proposed MR damper showed the better performance in reducing the absolute acceleration with the larger frictional force than the passive one. Also, the results from a three-storey benchmark building indicated that the proposed decentralized MR damper provided control performance equivalent to or better than the performance shown by the semiactive MR damper using a centralized LQR algorithm. Finally, the effectiveness of the proposed MR damper was verified through experimental tests of a full-scale five-storey steel structure with the MR dampers.

A Genetic Algorithm-based Two-phase Design for Optimal Placement of Semi-active Dampers for Nonlinear Benchmark Structure

Optimal placement of dampers for structural vibration control is both important and challenging. Though this issue is adequately addressed for linear structures in the literature, optimal placement of dampers for nonlinear structures is rarely studied. In this paper, a two-phase optimization process using genetic algorithms is proposed for the placement of semi-active MR dampers for a nonlinear benchmark structure. In the first phase, an optimization algorithm is used to obtain the active control force that is most suitable for semi-active implementation. In the second phase, the placement of semi-active MR dampers is optimized to mimic the optimal active control force obtained in the first phase. Simulation results show that the lower and upper stories will be the first choice for the placement of the dampers, and also the optimal number of the MR dampers for a structure is suggested in this paper.

Semi-active suspension systems for railway vehicles using magnetorheological dampers. Part II: simulation and analysis

In this paper, the semi-active suspension system for railway vehicles based on the controlled (MR) fluid dampers is investigated, and compared with the passive on and passive off suspension systems. The lateral, yaw, and roll accelerations of the car body, trucks, and wheelsets of a full-scale railway vehicle integrated with four MR dampers in the secondary suspension systems, which are in the closed and open loops respectively, are simulated under the random and periodical track irregularities using the established governing equations of the railway vehicle and the modelled track irregularities in Part I of this paper. The simulation results indicate that (1) the semi-active controlled MR damper-based suspension system for railway vehicles is effective and beneficial as compared with the passive on and passive off modes, and (2) while the car body accelerations of the railway vehicle integrated with semi-active controlled MR dampers can be significantly reduced relative to the passive on and passive off ones, the accelerations of the trucks and wheelsets could be increased to some extent. However, the increase in the accelerations of the trucks and wheelsets is insignificant.

MR 감쇠기의 준능동 퍼지제어기법을 이용한 인접구조물의 지진응답제어

인접건물 사이에 감쇠기 형태의 에너지 소산장치를 설치하고 연결함으로써, 지진 응답을 줄이고 내진 성능을 향상시킬 수 있는 방법에 대하여 연구를 수행하였다. 서로 인접한 건물 간의 진동제어를 위하여 준능동 MR 감쇠기를 이용하는 퍼지 제어기법을 제시하고, MR 감쇠기의 감쇠력 조절을 시간에 따라 제어할 수 있도록 제시한 방법으로 제어기를 설계하였다. 제시한 방법의 타당성을 검증하기 위하여 수치모사를 수행하였으며, 다양한 역사지진의 지진응답 해석을 통해서 비제어시, 수동제어 및 준능동 퍼지제어 등에 대한 최대응답을 비교 분석하였다. 수치모사 결과 제시한 방법은, 다양한 주파수 성분을 가진 여러 가지 지진에 대해 매우 효과적인 제진 성능을 보이는 것으로 나타났다. In this paper, a method for reducing seismic responses of adjacent buildings is studied that involves connecting two buildings with energy-dissipating devices, such as MR dampers. For the vibration control of the adjacent buildings, a fuzzy control technique with semi-active MR dampers is proposed. A fuzzy controller, which can appropriately modulate the damping forces by controlling the input voltage in real time, is designed according to the proposed method. To verify the validity of the proposed method, numerical simulations are performed. In the numerical simulations, historical earthquake records with diverse frequency contents and different peak values are used. For the purpose of comparison, an uncontrolled system, a passive control system and a semi-active fuzzy control system are considered. The comparative results prove the effectiveness of the proposed control technique, i.e. the numerical results show that the fuzzy controlled semi-active MR dampers can effectively reduce the earthquake responses of the adjacent structures.

Application of adaptive fuzzy sliding mode control to a seismically excited highway bridge

This paper presents an application of adaptive fuzzy sliding mode control (AFSMC) for a benchmark problem on a seismically excited highway bridge. This approach combines great advantages of sliding mode control (SMC), adaptive control and fuzzy control without compromising the stability or robustness. Switching-type control law of the conventional SMC and uncertainty part of the equivalent control is approximated by fuzzy controller to attenuate the chattering phenomenon of SMC and harmful effects caused by uncertainties. In order to reduce the complexity of the fuzzy rule bases, adaptive law based on Lyapunov function and Barbalat lemma is designed. AFSMC is also integrated with clipped-optimal strategy to illustrate its efficiency for semi-active MR dampers. Robustness of the AFSMC controller has been demonstrated analyzing ±30% perturbation in the stiffness of the bridge. Numerical results indicate that the response quantities of the highway bridge can be reduced to a satisfactory level superior to those of the sample LQG and LQG/clipped-optimal algorithms. Copyright © 2009 John Wiley & Sons, Ltd.

漸硬型抵抗力特性を持つ受動型MRダンパ : 準能動型MRダンパとの比較(機械力学,計測,自動制御)

漸硬型抵抗力特性を持つ受動型MRダンパ : 準能動型MRダンパとの比較(機械力学,計測,自動制御)

Stochastic change detection in uncertain nonlinear systems using reduced-order models:classification

A reliable structural health monitoring methodology (SHM) is proposed to detect relativelysmall changes in uncertain nonlinear systems. A total of 4000 physical tests were performedusing a complex nonlinear magneto-rheological (MR) damper. With the effective (or‘genuine’) changes and uncertainties in the system characteristics of the semi-active MRdamper, which were precisely controlled with known means and standard deviation of theinput current, the tested MR damper was identified with the restoring force method(RFM), a non-parametric system identification method involving two-dimensionalorthogonal polynomials. Using the identified RFM coefficients, both supervised andunsupervised pattern recognition techniques (including support vector classification andk-means clustering) were employed to detect system changes in the MR damper. Theclassification results showed that the identified coefficients with orthogonal basis functioncan be used as reliable indicators for detecting (small) changes, interpreting the physicalmeaning of the detected changes without a priori knowledge of the monitoredsystem and quantifying the uncertainty bounds of the detected changes. Theclassification errors were analyzed using the standard detection theory to evaluate theperformance of the developed SHM methodology. An optimal classifier designprocedure was also proposed and evaluated to minimize type II (or ‘missed’) errors.