Semi‐active predictive control of non‐linear structures with controlled stiffness devices and friction dampers

A predictive semi‐active control system used to improve the response of non‐linear multistorey structures to earthquakes is presented. A system of controlled stiffness devices (CSD) and friction dampers (FD) is studied. The system combines the forces produced by the semi‐active FD and additional stiffness supplied by the CSD in order to obtain an optimal structural response. A predictive algorithm is used to overcome the time delay problem in the control system. The control forces in the FD are calculated at every time step by applying the instantaneous optimum control law according to the structural behaviour predicted for the next time step at each storey level of the structure. The proposed system can be efficiently used for structural control because the forces developed in it are independent of the structure's displacements or velocities. Its efficiency is demonstrated by a numerical simulation of a seven‐storey building subjected to various seismic excitations. The simulation shows that the behaviour of a structure with the proposed control system is significantly improved compared to an uncontrolled one, or controlled by friction dampers or by semi‐active controlled stiffness devices only. The structural response with a predictive controlled system is similar to that with an instantaneous one. Copyright © 2004 John Wiley & Sons, Ltd.     

Model‐Based Multi‐input,Multi‐output Supervisory Semi‐active Nonlinear Fuzzy Controller

Abstract: The authors recently proposed a new multi‐input, single‐output (MISO) semi‐active fuzzy controller for vibration control of seismically excited small‐scale buildings. In this article, the previously proposed MISO control system is advanced to a multi‐input, multi‐output (MIMO) control system through integration of a set of model‐based fuzzy controllers that are formulated in terms of linear matrix inequalities (LMIs) such that the global asymptotical stability is guaranteed and the performance on transient responses is also satisfied. The set of model‐based fuzzy controllers is divided into two groups: lower level controllers and a higher level coordinator. The lower level fuzzy controllers are designed using acceleration and drift responses; while velocity information is used for the higher level controller. To demonstrate the effectiveness of the proposed approach, an eight‐story building structure employing magnetorheological (MR) dampers is studied. It is demonstrated from comparison of the uncontrolled and semi‐active controlled responses that the proposed design framework is effective in vibration reduction of a building structure equipped with MR dampers.     

A hybrid LQR-PID control design for seismic control of buildings equipped with ATMD

This paper presents an efficient hybrid control approach through combining the idea of proportional-integral-derivative (PID) controller and linear quadratic regulator (LQR) control algorithm. The proposed LQR-PID controller, while having the advantage of the classical PID controller, is easy to implement in seismic-excited structures. Using an optimization procedure based on a cuckoo search (CS) algorithm, the LQR-PID controller is designed for a seismic- excited structure equipped with an active tuned mass damper (ATMD). Considering four earthquakes, the performance of the proposed LQR-PID controller is evaluated. Then, the results are compared with those given by a LQR controller. The simulation results indicate that the LQR-PID performs better than the LQR controller in reduction of seismic responses of the structure in the terms of displacement and acceleration of stories of the structure.     

Semi‐active control of seismic response of tall buildings with podium structure using ER/MR dampers

A tall building with a large podium structure under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the podium structure. This paper thus explores the possibility of using electrorheological (ER) dampers or magnetorheological (MR) dampers to connect the podium structure to the tower structure to prevent this whipping effect and to reduce the seismic response of both structures. A set of governing equations of motion for the tower–damper–podium system is first derived, in which the stiffness of the member connecting the ER/MR damper to the structures is taken into consideration. Based on the principle of instantaneous sub‐optimal active control, a semi‐active sub‐optimal displacement control algorithm is then proposed. To demonstrate the effectiveness of semi‐active control of the system under consideration, a 20‐storey tower structure with a 5‐storey podium structure subjected to earthquake excitation is finally selected as a numerical example. The results from the numerical example imply that, as a kind of intelligent control device, ER/MR dampers can significantly mitigate the seismic whipping effect on the tower structure and reduce the seismic responses of both the tower structure and the podium structure. Copyright © 2001 John Wiley & Sons, Ltd.     

Semi‐active algorithm for energy‐based predictive structural control using tuned mass dampers

A novel semi‐active control algorithm is developed and numerically evaluated for the suppression of undesirable structural vibrations. The mechanical energy of the vibrating structure is considered as the primary variable influencing the control action. This intuitive strategy is proposed to realize improved control of structural vibrations. The numerical study conducted reveals that the proposed energy‐based predictive (EBP) algorithm can be implemented on vibration control applications. The energy imparted to the structure is also reduced due to the proposed algorithm. The influence of the parameters of the proposed semi‐active tuned mass damper is studied. Further, the application of the proposed strategy on a realistic structure is numerically demonstrated by implementing the algorithm for the wind response control of a 76‐story benchmark building. The results show that the EBP algorithm is a competitive semi‐active strategy. The robustness of the strategy is also evaluated considering uncertainties in the properties of the benchmark building.     

On the efficiency of semi‐active smart structures: self‐regulating MR dampers control system for tall buildings

Many severe dynamical loadings such as earthquakes and strong winds may subject to structural systems during their lifetime and lead to changes in structural characteristics. Hence, employing an adaptive control strategy that can deal with these alterations compound with design of the structural elements would undoubtedly be the most effective alternative design for the old‐fashioned design methods, which are relatively inefficient in response to these unforeseen conditions. In the current study, benefits of employing the modern control systems for design of tall buildings in comparison with the uncontrolled traditionally designed structures are thoroughly investigated. To contract the vibrational responses due to seismic excitations, the innovative direct‐modulating semi‐active controller is designed for magneto‐rheological dampers, which are installed in an 11‐storey sample building converting it to a smart structure. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimal control of structures under earthquake excitation based on the colonial competitive algorithm

The active control of engineering structures is one of the best methods to reduce structural responses under seismic excitation for the best performance of structures. This study presents an effective approach for the optimal control of structures under strong ground motion using the colonial competitive algorithm. The colonial competitive algorithm was developed over the last few years in an attempt to overcome the inherent limitations of traditional optimize method. The colonial competitive algorithm has been applied due to its ideal performance in optimal control problem. The effectiveness and performance of the proposed method have been investigated through two numerical examples for the response control of earthquake‐excited structures. The obtained results have been compared with the Linear Quadratic Regulator (LQR) control algorithm, and the performance of the proposed control approach has been found to be better than the LQR controller. Copyright © 2012 John Wiley & Sons, Ltd.     

Base‐isolated structures with selective controlled semi‐active friction dampers

This paper investigates effectiveness of selective control strategy in hybrid base isolation systems including isolators and semi‐active variable friction (VF) dampers. According the selective control strategy, VF dampers are activated just if the displacement at the isolators exceeds the threshold value. The slip‐force control is based on the values of floors' accelerations and velocities. By controlling the slip‐force magnitude in the VF dampers, effective energy dissipation can be achieved in a seismic event. Activation of dampers according to the selective control strategy allows high‐energy dissipation by minimum energy required for adjusting the slip‐force. Performance of a multi‐storey frame with a base isolation system and VF dampers under various earthquake records was obtained numerically using originally developed MATLAB routines. Seismic response of the analysed structure with the selective controlled system was compared with that when the VF dampers were active during the whole earthquake. It is shown that adjustment of the slip‐force in a selective manner allows additional reductions in peak displacements and accelerations of the structure. The results also demonstrate that this control strategy yields reduction of the base displacement without increasing the peak base shear forces. Copyright © 2009 John Wiley & Sons, Ltd.     

Performance of fixed‐parameter control algorithms on high‐rise structures equipped with semi‐active tuned mass dampers

The present study investigates the performance of fixed parameter control algorithms on wind‐excited high‐rise structures equipped with semi‐active tuned mass dampers of variable damping. It has been demonstrated that the algorithms that increase significantly the performance of the controlled structure do so at the expense of damper strokes. When the maximum damper strokes are capped to progressively lower limits, the efficacy of different algorithms, measured through a number of performance objectives, drastically alters totally changing the performance ranking of them and pointing out the need for an extensive study of the interplay between loading, control algorithm and allowable stroke within the design of semi‐active tuned mass dampers devices. 2015 The Authors. The Structural Design of Tall and Special Buildings published by John Wiley & Sons Ltd.     

Semi‐active control for eccentric structures with MR damper based on hybrid intelligent algorithm

In this paper, an application of the hybrid intelligent control algorithm to semi‐active control of the magnetorheological (MR) damper is presented for engineering structures. The control signal is optimized directly by the µGA approach to obtain the numerical relation between the control signal and the system output. This relation is then stored in the weight value of a trained artificial neural network, which can be available for another structure subjected to other seismic inputs. The results of a numerical example indicate that the semi‐active control of the MR damper based on the hybrid algorithm can efficiently reduce the structural responses induced by an earthquake. Copyright © 2007 John Wiley & Sons, Ltd.     

基于状态微分控制算法的空间结构主动振动控制分析

对于主动振动控制器的设计,传统的控制算法以速度和位移作为系统的输入量,但速度和位移难以观测,给实际应用带来了较大的误差.本文在振动状态空间方程的基础上,对其进行矩阵运算,形成以加速度为系统输入的状态微分反馈控制方程.构造具有约束条件的目标函数,根据Lagrange乘子法和泛函极值运算确定了状态反馈矩阵和状态反馈估计值,从而构造了闭环的状态微分控制算法.根据此算法对一直径为1m的环形空间结构进行了振动控制仿真,利用时域内的模态参数识别方法,对控制效果进行了评价,并以三层剪切型框架结构为对象,对状态微分控制算法和传统的LQR算法进行了控制效果的对比分析.结果表明,利用状态微分控制算法在空间结构上的振动控制是可行的,且减振效果明显,同时优于传统的LQR控制算法.     

A new control algorithm to protect nonlinear base‐isolated structures against earthquakes

Currently, nonlinear base isolation systems are widely used in the construction of earthquake resistant structures. However, they are found to be vulnerable in near‐fault regions as a result of long‐period pulses that may exist in near‐source ground motions. Various control strategies including passive, active and semi‐active control systems have been studied in order to handle this issue. In this study, a semi‐active control algorithm based on the different performance levels anticipated from an isolated building during different levels of ground shaking was developed. The proposed performance‐based algorithm is based on a modified version of the well‐known semi‐active skyhook control algorithm. A series of analyses were performed on the base‐isolated benchmark building, suggested by the American Society of Civil Engineers committee, subject to seven pairs of scaled ground‐motion records. The results proved that the new control algorithm is successful in improving structural and nonstructural performance of isolated buildings under near‐fault earthquakes. Copyright © 2012 John Wiley & Sons, Ltd.     

Semi‐active friction system with amplifying braces for control of MDOF structures

The development and applications of a semi‐active friction damping system with amplifying braces is studied. A system of dampers and braces, defined as the friction damping system with amplifying braces (FDSAB) is considered. Active control theory with velocity and acceleration feedback is used to obtain the control forces in the proposed system. The system can be used efficiently to enhance the damping of a structure and improving its response. The efficiency of the proposed system is demonstrated by the numerical simulation of a seven storey building subjected to earthquakes. The simulation shows that the behaviour of the damped structure with the FDSAB is significantly improved. The required control forces are much less compared with a control system with semi‐active friction dampers connected either to chevron or diagonal braces. Copyright © 2001 John Wiley & Sons, Ltd.     

不同控制策略下安装磁流变阻尼器的模型结构振动台试验与分析

本文对不同控制策略下安装有磁流变(MR)阻尼器的模型结构进行了振动台试验和分析。文中首先介绍了经典最优控制(COC)、瞬时最优控制(IOC)和线性二次高斯最优控制(LQG)等三种控制算法,然后对一首层安装有最近设计制造的MRF-04K型的MR阻尼器的、1/3比例的三层钢框架模型,进行了在两种被动控制和三种半主动控制等不同控制策略下的振动台试验,最后对模型结构地震反应的控制效果以及不同控制策略对控制效果的影响和控制稳定性进行了分析。研究表明,安装有MRF-04K阻尼器的结构控制系统具有良好的控制效果,无论是被动控制还是半主动控制,模型结构各层相对位移峰值均减小了45%左右,其均方根值均减小了70%左右,加速度反应峰值均减小了30%左右,其均方根值均减小了75%左右,从而验证了MRF-04K阻尼器是结构控制工程应用的一种理想的控制装置;研究还表明,在三种半主动控制策略中,基于LQG算法的半主动控制仅需模型结构的加速度反应的反馈信息,比基于IOC算法和COC算法的半主动控制     

Hybrid actuator–damper–bracing control (HDABC) system with intelligent strategy and soil–structure interaction

The hybrid actuator–damper–bracing control (HDABC) system is composed of visco-elastic dampers and hydraulic actuators as the passive and active controllers, respectively, which are installed on the brace and connected to the building floor. The intelligent control strategy is designed to maximally utilize the passive damper and to minimally utilize the active energy. Thus, the passive controller of the hybrid system is designed for small and moderate earthquakes and the active controller works for large earthquakes, whenever the structural response exceeds the threshold values. The hybrid control system with this strategy is studied under existing earthquake records and the ground motions generated considering the tectonic movements of seismic plates; the influence of soil–structure interaction (SSI) on the control effectiveness is investigated. Based on analyses of single-story and six-story structures, it is concluded that the intelligent strategy is effective for the hybrid control, and SSI needs to be included in the design of the intelligent hybrid system as well as other types of control for buildings on soft soil.     

Selective combined control stiffness and magnetorheological damping system in nonlinear multistorey structures

The application of a combined controlled stiffness and magnetorheological (MR) damping system in a base‐isolated nonlinear multistorey structure with amplifying braces is described. Passive control theory is used to obtain the viscous characteristics of the MR damper fluid. Selective control of the proposed system is used to enhance the behaviour of a structure during earthquakes. The nonlinear equations of motion are solved using the Wilson θ method. The control forces are obtained using instantaneous control theory with the predictive control approach. The efficiency of the proposed system is demonstrated by a numerical simulation of a seven‐storey building subjected to four different earthquakes. The stimulation shows that the behaviour of the selective controlled structure with the proposed damping system is significantly improved compared to that of an uncontrolled structure. The energy required for the adjustment of the proposed system with amplifying braces is much lower compared to that of the case of MR dampers connected directly to chevron braces. The response of the predictive controlled structure is close to that of an instantaneous controlled structure. Copyright © 2002 John Wiley & Sons, Ltd.     

Semi‐active control devices in structural control implementation

A semi‐active control device for structural control implementations is presented and discussed in this paper. Based on two passive control devices, the mass pump and the hydraulic mass system, a new passive control system, the mass damper pump (MDP), is introduced. It is found that the MDP system is more effective in vibration control than the other two passive control systems. It is then shown that the passive control MDP can be modified to be a semi‐active control device and is very effective in structural control. Through theoretical analysis and numerical simulations, it is found that the proposed semi‐active control device MDP is more suitable for structures with ordinary height or the magnitude of earthquake excitations is not very large (because the control force provided by the semi‐active control is limited). Under these situations, the maximum response of a controlled structure can be reduced by one‐third to one‐half. Also, it is found that multiple MDP is more effective in reducing structural response than a single MDP when they are placed in appropriate locations. Copyright © 2005 John Wiley & Sons, Ltd.     

MR阻尼器在海洋平台半主动振动控制中的应用

采用磁流变 (MR)阻尼器对海洋平台的半主动振动控制效果进行研究 ,建立海洋平台磁流变 (MR)半主动控制结构的数学模型 ,提出基于现代最优控制理论的半主动控制方法 ,算例仿真结果表明 ,采用磁流变阻尼器对海洋平台进行半主动控制能够有效的减小平台的振动响应     

Active and Semi‐active Adaptive Control for Undamaged and Damaged Building Structures Under Seismic Load

Abstract: During the lifetime of a structural system, many severe events such as earthquakes and strong winds may impact the system and result in potential damage. To mitigate the structural vibration and damage during these extreme events, control devices such as active and semi‐active devices have received considerable attention because of their attractive characteristics. Active control devices are adaptable to any change and semi‐active devices have the capability of offering the reliability of passive devices and the versatility and adaptability of active devices. In this research, a direct‐adaptive‐control method is used to control the behavior of an undamaged and a damaged structure using semi‐active and active devices. In the adaptive control method, the controlled system is forced to behave like the model system which exhibits the desired behavior. The model of the adaptive control method is defined in a way to optimize the response of the controlled structure. The controller developed using this method can deal with changes that occur in the characteristics of the structure because it can modify its parameters during the control process. A magnetorheological (MR) damper is used as the semi‐active device in this study, whereas a hydraulic actuator is utilized as the active device to control the behavior of the structure. The performance of a three‐story building from the SAC project for the third generation of the control benchmark problem is studied by performing time–history analyses. The structure is subjected to different earthquakes and controlled by the direct adaptive control method. In the analysis of the structure, some stiffness reduction is assumed as a result of potential damage in the first story of the building. Also, the direct adaptive control strategy is used to optimize the response of the undamaged structure and to mitigate the damage impact on the performance of the controlled structure in the presence of noise for output measurements. The results of adaptive control method are compared with those of other control strategies. It is shown that the performance of the three‐story building is improved using the adaptive control method. By assessing the results of different control approaches, it is found that the adaptive control method works more effectively than other methods and semi‐active devices can provide reliable results.     

磁流体阻尼器半主动控制结构的地震反应分析

对磁流变阻尼器的性能及恢复力模型进行了介绍,并对其参数进行了设计,提出了基于经典线性最优控制算法和瞬时最优控制算法的半主动控制律.通过对一装有七个MR阻尼器的七层框架结构的地震反应分析表明,基于这两种控制算法的半主动控制律是非常有效的,并且该半主动控制方法能够有效地减小结构的地震反应.