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 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.     

Seismic response of semi‐active friction‐damped reinforced concrete structures with self‐variable stiffness

The influence of structural self‐variable stiffness and semi‐active friction dampers on the behavior of reinforced concrete (RC) buildings during strong earthquakes is discussed. A fully braced six‐story beamless RC frame is analyzed. The effect of concrete braces (with only constructive reinforcement) as a self‐variable mechanism is studied. It is shown that up to a certain limit the frame itself controls its behavior by adapting its dynamic characteristics in the real time of the earthquake. This self‐adaptation is achieved by autonomous disengagement of the braces under tension and their further nonlinear action under compression. The system has several levels of seismic adaptation, and it selects one of them for enhanced response to the given earthquake. However, when the limit is reached, further self‐adaptation of the frame becomes impossible. The occurrence of an earthquake of higher magnitude can then lead to disengagement of the concrete braces under compression, intensifying structural damage and even causing collapse. The use of semi‐active controlled friction dampers is proposed as a means of preventing the collapse of braces under compression, thereby enabling structures to withstand earthquakes. The forces in the friction dampers are regulated according to an optimal control algorithm. Modulation of the friction level in real time during the earthquake yields additional improvement of structural seismic behavior and obviates the need for retrofitting. Copyright © 2007 John Wiley & Sons, Ltd.     

Pall型摩擦阻尼支撑体系试验研究

鉴于Pall型摩擦阻尼普通支撑会对框架边柱产生附加轴力,考虑采用防屈曲支撑来代替普通支撑,使支撑充分发挥作用,同时不会对边柱产生增长的附加轴力,为防屈曲支撑在Pall型摩擦阻尼支撑体系中的应用奠定基础.由于Pall型摩擦阻尼器滞回特性不受支撑屈曲力影响的特性,故采用普通钢板来代替防屈曲支撑进行Pall型摩擦阻尼支撑体系试验研究,同时对此支撑体系在考虑几何非线性情况下进行有限元AN-SYS仿真分析.对比试验结果和仿真分析结果,表明试验结果与仿真分析结果得出的Pall型摩擦阻尼器摩擦力和支撑内力的变化规律基本相同,为下一步采用防屈曲支撑体系进行试验研究奠定基础.     

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.     

Support vector machine based semi‐active control of structures: a new control strategy

The present paper presents the support vector machine (SVM)‐based semi‐active control algorithm used for designing general dampers for multistorey structures under earthquakes. First, the linear quadratic regulator (LQR) controller for the numerical model of a multistorey structure formulated using the dynamic dense method is obtained by using the classic LQR control theory. Then, a SVM model is designed and trained to emulate the performance of the LQR controller. Likewise, this SVM model comprises the observers and controllers of the control system. Finally, in accordance with the features of general semi‐active dampers, a SVM‐based semi‐active control strategy is put forward. More specifically, an online auto‐feedback semi‐active control strategy is developed and then realized by resorting to SVM. In order to numerically verify the control effectiveness of the present control strategy, the time history analysis has been implemented to a structure with general dampers designed by the SVM‐based semi‐active control algorithm. In numerical simulations, four seismic waves including the El Centro, Hachinohe and Kobe waves, as well as the Shanghai artificial wave, whose peak ground accelerations are all scaled to 0.1 g, are taken into consideration. Comparative results demonstrate that general semi‐active dampers designed using the SVM‐based semi‐active control algorithm is capable of providing higher level of response reduction. Copyright © 2009 John Wiley & Sons, Ltd.     

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.     

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.     

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.     

高层建筑结构的风振阻尼控制分析与设计方法

本文首先分析了阻尼比对结构风振反应的控制效果,重点讨论了阻尼比对风振脉动增大系数的减小效果和具体计算方法,给出了便于工程实际应用的阻尼比为10%～30%的风振脉动增大系数随基本风压和结构基本周期变化的计算图表。结果表明,结构阻尼比增大,风振脉动增大系数明显减小。其次,分析了结构耗能减振系统的附加阻尼特性,给出了调频质量阻尼器(TMD)、调频液体阻尼器(TLD)和速度线性相关型耗能器附加给结构阻尼比的实用计算公式。最后给出了100层钢结构分别设置TMD和线性粘滞阻尼器的风振控制分析和设计实例。实例结果表明,两种被动阻尼控制系统对结构最大位移和最大加速度控制效果相同,可以达到40%～55%,同时说明了本文提出的方法可以方便地用于大型结构的风振阻尼控制分析和设计。     

High‐efficiency amplifiers for viscous damped structures subjected to strong earthquakes

Amplifying devices increase the displacements and the velocities that are transferred to the dampers attached to them, enabling the use of viscous dampers with lower damping coefficients in order to achieve optimal structural behavior. A known design algorithm for such devices simplifies the real behavior of the amplifier by assuming small displacements and velocities, which are transferred to the damper. This algorithm is likely to be less effective under strong earthquakes that induce large displacements and velocities. This paper discusses high‐efficiency amplifiers that have large amplifying ratios and proposes an improved method, which takes into account more accurate values of the displacements and velocities transferred to the damper, in order to obtain an enhanced structural response to earthquakes. The efficiency of the proposed method is demonstrated in a numerical simulation of a shear framed eight‐story reinforced concrete viscous damped structure. The simulation compares the behavior of the structure designed according to the simplified and to the proposed algorithms. It shows that for relatively large amplifying ratios and for drifts induced by strong earthquakes the proposed methodology yields better results. Copyright © 2006 John Wiley & Sons, Ltd.     

Energy‐based predictive algorithm for semi‐active tuned mass dampers

There are various control strategies proposed and implemented for the protection of structures against different types of dynamic excitations. Currently, semi‐active control devices are very popular due to their adaptability and low power requirement. In this paper, a novel energy‐based predictive (EBP) algorithm is proposed, and its effectiveness is studied when applied to semi‐active tuned mass damper (SATMD). The mechanical energy of the primary structure is taken as the key parameter to be used by the algorithm to predict a suitable value of the manipulated variable, the damping of the tuned mass damper (TMD). The choice of the damping is made such that the damping used at a time interval leads to the least possible mechanical energy of the primary structure. The efficacy of the proposed control algorithm is studied by employing the EBP algorithm on single‐story and multistory structures equipped with the SATMD. The performance of the proposed algorithm when applied to the SATMD is also compared with that with the passive TMD for similar parameters. The results of the study show that the implementation of the EBP algorithm leads to significantly reduced dynamic response as compared with the passive TMD. Furthermore, numerical studies are conducted to gain insight into the effect of various parameters such as the mass ratio, the TMD damping ratio, and the flexibility of the structure.     

浅议摩擦阻尼减震技术的研究应用

近年来,基于性能设计的结构减震技术发展迅速。试验及理论分析表明,采用安装摩擦阻尼器的耗能支撑来保护结构,可耗散大量地震能量,减震效果好。本文主要介绍了摩擦耗能器的发展历史、工作原理、国内外的试验研究情况,同时介绍了在工程中的典型应用。     

底层柔性柱隔震结构半主动控制研究

为减小隔震结构底部柔弱层的过大变形,提出了一种底层柔性柱隔震结构半主动控制体系。将结构底层柱设计成柔性柱,在底部填充墙与二层梁之间安装磁流变阻尼器,根据主动控制算法来适时调整阻尼器的阻尼力,对结构实施限位和耗能的半主动控制。建立结构振动模型,通过数值模拟分析该体系的振动特点和减震效果。研究表明,这种结构控制体系能有效减小结构的地震反应,隔震层位移减小50%以上,防止结构因底部位移过大而倒塌。隔震层刚度对减震效果有明显影响,层间刚度比应在隔震层位移、层间位移和加速度之间权衡考虑,并保证底层柱在大震下不发生失稳。在没有半主动控制条件的情况下,在隔震层安装固定阻尼耗能器件进行被动控制,也可减小底层位移30%以上。     

具自复位功能的同心斜撑构架耐震行为研究

一般而言,同心斜撑构架(CBF)通过对角配置斜撑来消散地震力。然而在地震过后结构物留下过大的残留变形,使得结构物难以修复。故该文对具自复位功能同心斜撑构架受震后可减少残留变形的可行性进行探讨。在类似的文件中,由于在梁柱接合处将两者分开,受地震时令梁端可在柱面上进行摇摆,而并没有引发任何损坏。提出通过梁翼板底部所安装的摩擦阻尼器或在斜撑上安装摩擦阻尼器或摩擦铰阻尼器,为验证此设计想法,该文设计一个实际尺寸的构架,此构架为单层单垮的同心斜撑构架,并在横向进行循环反复载重试验。而研究参数包含能量消散的形式不同或是位置不同与摩擦材料的不同,如磷青铜和黄铜。而试验的结果显示,具自复位功能同心斜撑构架可实现少量的残留变形与适当的耐震性能。由所有的试验可看出,使用磷青铜摩擦阻尼器的斜撑比其他形式斜撑消散较多能量。     

Failure probability minimization of buildings through passive friction dampers

This paper proposes a methodology for robust optimization of the failure probability of buildings subjected to stochastic earthquakes, using a less common type of passive energy dissipation device: the friction dampers. There is a lack of studies on optimal positions and parameters of passive friction dampers, and additionally, the few studies found in the literature consider the problem in a deterministic way. The robust optimization proposed in this paper is carried out through the recently developed backtracking search optimization algorithm, which is able to deal with optimization problems involving mixed discrete (positions) and continuous (friction forces) design variables. In order to take into account uncertainties present in both the system and the dynamic excitation (earthquakes), some parameters are modeled as random variables, and consequently, the structural response becomes stochastic. For illustration purposes, a 10‐story building is analyzed. The results showed that the proposed method was able to reduce the failure probability in approximately 99% with only three friction dampers, installed in their best positions and with their optimized friction forces. The proposed methodology is quite general, and it is believed that it can be recommended as an effective tool for optimum design of friction dampers. Copyright © 2016 John Wiley & Sons, Ltd.     

Simplified optimal design of MDOF structures with negative stiffness amplifying dampers based on effective damping

This paper presents a study on multi‐degree‐of‐freedom (MDOF) structures equipped with a negative stiffness amplifying damper (NSAD). The NSAD not only preserves the negative stiffness feature of negative stiffness devices (NSDs) but also achieves prominent damping magnification effect, substantially reducing a NSD's requirement for high additional damping, which is used to contain the increased displacements resulting from the reduction in overall stiffness of a system. The dynamic equations of MDOF systems with NSADs are described in state–space representation, and the effective damping and frequencies are parametrically studied. Then, a simple optimization method is proposed. A study of the 20‐storey benchmark building shows that NSADs are the most efficient of supplemental devices in reducing interstorey drifts compared with viscous dampers (VDs) and viscoelastic dampers (VEDs) with the same supplemental damping coefficient. For instance, when compared with that of VEDs, the maximal peak interstorey of NSADs can be further reduced by about 30%. In terms of reducing acceleration responses, NSADs perform much better than VDs and VEDs owing to their negative stiffness feature. Partially arranged, NSADs are best implemented at the storeys that have smaller interstorey drift responses. This is because the negative stiffness preserved by NSADs significantly reduces the interstorey drift of storeys without NSADs.     

Optimization layout of viscous dampers and its application in retrofitting of a high-rise steel structure

阻尼器优化布置是结构减震设计过程中的重要环节，通常需要通过多次动力响应计算来完成。为此，提出了一种通过结构静力分析确定阻尼器合理布置位置的方法，并能够快速计算出优化方案的附加阻尼比。将该方法应用于一栋位于日本东京都新宿区29层钢结构建筑的减震加固设计中，分析了该建筑的强震观测系统在日本“311地震”中采集到的部分楼层加速度时程数据，并基于分析结果验证了所建立的非线性数值分析模型的可靠性。采用所提方法对结构进行减震加固，得到双向共64个阻尼器的优化布置方案及其附加阻尼比，并通过动力方法对结果进行了验证。同时针对长周期及长持时特性的地震波，对减震结构进行动力弹塑性时程分析，评估其抗震性能。分析结果表明：减震优化方案的减震效果明显，结构整体地震反应和构件损伤较非减震方案都大大减小；减震优化方案有效改善了高层钢结构楼层变形不均匀的情况，层间位移角均满足小于1/100的性能要求；通过减震优化后大部分钢支撑和钢梁的塑性率都降低至小于1。     

黏滞阻尼器的优化布置及其在高层钢结构加固中的应用

阻尼器优化布置是结构减震设计过程中的重要环节,通常需要通过多次动力响应计算来完成。为此,提出了一种通过结构静力分析确定阻尼器合理布置位置的方法,并能够快速计算出优化方案的附加阻尼比。将该方法应用于一栋位于日本东京都新宿区29层钢结构建筑的减震加固设计中,分析了该建筑的强震观测系统在日本“311地震”中采集到的部分楼层加速度时程数据,并基于分析结果验证了所建立的非线性数值分析模型的可靠性。采用所提方法对结构进行减震加固,得到双向共64个阻尼器的优化布置方案及其附加阻尼比,并通过动力方法对结果进行了验证。同时针对长周期及长持时特性的地震波,对减震结构进行动力弹塑性时程分析,评估其抗震性能。分析结果表明：减震优化方案的减震效果明显,结构整体地震反应和构件损伤较非减震方案都大大减小;减震优化方案有效改善了高层钢结构楼层变形不均匀的情况,层间位移角均满足小于1/100的性能要求;通过减震优化后大部分钢支撑和钢梁的塑性率都降低至小于1。     

Developing a Smart Structure Using Integrated Subspace‐Based Damage Detection and Semi‐Active Control

Damage detection in large building structures has always faced challenges due to analyzing the large amount of measured data. In this article, a new damage detection approach based on subspace method is proposed to identify damages using limited output data. Also, a new scheme is presented to develop a smart structure by integrating structural health monitoring with semi‐active control strategy. If damage occurs in such a structure under severe excitations, the proposed scheme has the capability to exert necessary control forces in order to compensate for damage and reduce simultaneously the dynamic response of the structure. The reliability and feasibility of the proposed method are demonstrated by implementing the technique to two shear building structures with semi‐active control devices. Results show that the damage could be identified accurately with saving time and cost due to less computation even under noise existence; and dynamic response is significantly reduced in the smart structure.