TMD基础隔震混合减震体系地震响应研究

针对基础隔震体系遭受强地震时隔震层位移较大问题,提出了将调谐质量阻尼器(TMD)与基础隔震技术联合应用,形成一种新型的混合减震体系,以此控制隔震层的位移,同时减小上部结构响应。以一栋七层基础隔震体系为仿真算例,分别分析地震激励下基础隔震结构、调谐质量阻尼器(TMD)设置于基础隔震结构底层和顶层的混合减震体系地震响应。仿真结果表明:附加调谐质量阻尼器(TMD)不但能够有效减小隔震层的地震响应,同时对上部结构的响应也有不同程度的减小;对于附加调谐质量阻尼器位于底层而言,质量调谐阻尼器(TMD)位于顶层能够更有效的减小基础隔震体系的地震响应。     

新型半主动调谐质量阻尼器减震性能的数值模拟

为了改良被动式调谐质量阻尼器(TMD)对建筑结构的减震效果,本文提出了一种新型的可实时调节频率和电涡流阻尼的半主动调谐质量阻尼器(SATMD)。由Hilbert-Huang变换(HHT)识别出结构的瞬时频率,通过基于HHT的控制算法实时调节SATMD的质量进行频率的调谐;通过基于线性二次型高斯(LQG)的控制算法实时调整磁导间距来调节电涡流阻尼系数。为了验证SATMD对建筑结构的减震效果,以一单自由度结构模型为例进行地震响应模拟,同时采用一经优化设计的被动TMD作为对比,并考虑由于主结构的累积损伤等引起自身频率下降而造成被动TMD的去谐效应。以主结构的加速度和位移时程峰值、整体均方根值及TMD的耗能性能作为评价指标,对比了SATMD在主结构发生损伤前后对被动TMD的改良效果。数值模拟结果表明,在主结构发生损伤前后,SATMD均比经优化设计的被动TMD有更好的减震效果及耗能能力。     

基于模态参与消减的直连拉索连接惯容系统的简易算法

高层建筑各层加速度响应峰值往往受到高阶模态的影响,文中通过模态参与消减机制来探究高层结构的模态参与因子对结构振动响应的影响,旨在消除高阶模态的影响,为实现高层建筑结构层间位移和加速度的同步控制提供新的设计方案。首先,基于地震输入减少特性,总结了直连拉索连接惯容系统的控制特点;然后,推导了基于模态参与消减的直连拉索连接惯容系统解析设计公式,从解析的层面揭示了惯容的表观质量与各阶模态参与因子的关系。基于该公式通过惯容表观质量的合理设定可以对模态参与因子进行调节,为拉索连接惯容系统的简化参数设计提供依据;最后,文中提出了全模态参与消减的简易算法,解决了全模态参与消减的惯容系统的实用化设计问题。     

结构最优主动调谐质量阻尼器风致振动控制的研究

基于我国现行的风荷载规范,建立了在风荷载作用下结构-主动调谐质量阻尼器(ATMD)系统的动力方程。定义ATMD最优参数准则为:结构-ATMD系统的位移或加速度响应方差的最小化。ATMD有效性的评价准则为:设置ATMD结构的最小化位移或加速度响应方差与未设置ATMD结构的位移或加速度响应方差之比(分别称为位移和加速度减振系数)。根据上述准则,在频域内数值研究了结构自振频率、标准化加速度反馈增益系数、质量比对ATMD系统的最优参数(包括最优频率比和阻尼比)、有效性和冲程的影响。此外,为了比较的目的,论文同时考虑了结构TMD风致振动控制的情况。     

拉索式旋转电涡流阻尼器的理论模型及频域响应分析

惯容器是一种新型的振动控制装置,该装置可以将螺杆的轴向运动转换为黏滞材料和旋转质量的高速旋转运动,使阻尼器的阻尼效应和质量效应得到放大。基于惯容器原理以及电涡流原理,提出一种新型的拉索式旋转电涡流阻尼器,为结构被动控制提供了新的设计思路。为研究这种新型惯容系统的减振机理,对安装拉索式旋转电涡流阻尼器单层框架的力学模型进行了探讨。推导出了配置惯容系统单质点体系的动力表达式,并基于此表达式探讨在频域内该惯容系统关键参数对单质点体系位移、速度和加速度响应的影响。结果表明:这种拉索式旋转电涡流阻尼器可以起到放大质量的效果,惯容系统可以有效地减少单质点体系的位移、速度和加速度响应幅值。     

层间隔震结构工作机理研究

本文建立了层间隔震结构动力分析模型,对层间隔震结构地震反应的主要影响系数进行了分析。结果表明:在一定的频率比范围内,当隔震层的位置较高时,隔震结构下部位移和上部加速度均显著减小,表现出与TMD相似的工作机理;当隔震层的位置较低时,隔震结构下部位移和上部加速度均变化不明显,其工作机理与基础隔震相似。隔震层的阻尼比对层间隔震结构的减震效果也有较大影响,阻尼比越大,减震效果越好。     

摩擦摆基础隔震结构多维地震反应分析

对摩擦摆基础隔震结构进行了单向、双向和三向地震反应对比分析,表明考虑双向水平地震动时摩擦摆基础隔震结构的支座位移增大,而结构的加速度和楼层剪力减小,其中对支座位移和结构加速度影响较大;考虑竖向地震动时摩擦摆基础隔震结构的支座位移略有减小,而结构的加速度和楼层剪力增大,其中对结构加速度影响较大.因而,在进行摩擦摆基础隔震结构地震反应分析时,应考虑多维地震动的影响.     

基础和屋顶隔震混凝土结构的地震振动台实验研究

通过使用平面尺寸为4.0m×4.0m的地震模拟器即振动台,对基础和屋顶隔震体系的控制性能进行了比较研究。试验包括三个三层无隔震、基础隔震和屋顶隔震混凝土框架结构模型。屋顶隔震包括板和叠层橡胶支座(LRB)。输入振动台的模拟地震动分别是1940N-S地震动、人工模拟山东地震动和人工模拟上海地震动。通过分析三个三层模型在白噪音扫描下的动力特性,首先评价了基础隔震与屋顶隔震体系的控制性能。实验结果显示,尽管基础隔震与屋顶隔震有着不同的工作原理,但基础隔震和屋顶隔震体系都能够明显地减小结构的位移和加速度响应(包括层间位移)。而且前者有更好的有效性。值得注意的是,屋顶隔震体系由于实施相对方便,因而可能成为减小中低层建筑结构地震损伤的优先选择。     

基于碰撞调谐质量阻尼器的矮塔斜拉桥减震研究

以一座矮塔斜拉桥为研究对象,分析碰撞调谐质量阻尼器对于该结构的抑震效果。首先介绍了新型碰撞调谐质量阻尼器（Pounding Tuned Mass Damper,PTMD）的减震机理及基于接触单元的非线性碰撞力模型;之后,通过ANSYS软件中的APDL语言实现了PTMD减震系统的时域分析方法,并通过三条实际地震记录验证了PTMD的抑震效果。数值分析结果表明:（1）传统调谐质量阻尼器（tuned mass damper,TMD）及新型PTMD对于矮塔斜拉桥的位移、加速度及塔身弯矩响应均有较好的抑制效果;（2）PTMD相比传统TMD多了一种碰撞耗能模式,其减震效果略高于传统TMD。     

利用惯容隔震系统的结构层间隔震研究

层间隔震技术对于结构竖向不规则以及结构增层等状况有良好的适用性。然而,层间隔震可能出现的较大隔震层变形会带来结构设计的困难。通过在隔震层中设置阻尼元件可以减少变形,但是过大的阻尼出力和过多的数量需求可能导致空间布置和安装不便。惯容元件为解决以上问题提供了一种新的途径。该研究提出采用惯容隔震系统作为层间隔震提高能量耗散效率的手段以控制地震响应,同时也给出了基于性能需求的惯容层间隔震的参数优化设计方法。并以一个标准钢结构模型验证了方法的有效性。结果表明:惯容元件的使用显著降低了上部子结构的地震响应和隔震层的变形,惯容系统实现了预期的耗能增效作用。     

Optimal design and effectiveness evaluation for inerter-based devices on mitigating seismic responses of base isolated structures

The optimal design and effectiveness of three control systems, tuned viscous mass damper(TVMD), tuned inerter damper(TID) and tuned mass damper(TMD), on mitigating the seismic responses of base isolated structures, were systematically studied. First, the seismic responses of the base isolated structure with each control system under white noise excitation were obtained. Then, the structural parameter optimizations of the TVMD, TID and TMD were conducted by using three different objectives. The results show that the three control systems were all effective in minimizing the root mean square value of seismic responses, including the base shear of the BIS, the absolute acceleration of structural SDOF, and the relative displacement between the base isolation floor and the foundation. Finally, considering the superstructure as a structural MDOF, a series of time history analyses were performed to investigate the effectiveness and activation sensitivity of the three control systems under far field and near fault seismic excitations. The results show that the effectiveness of TID and TMD with optimized parameters on mitigating the seismic responses of base isolated structures increased as the mass ratio increases, and the effectiveness of TID was always better than TMD with the same mass ratio. The TVMD with a lower mass ratio was more efficient in reducing the seismic response than the TID and TMD. Furthermore, the TVMD, when compared with TMD and TID, had better activation sensitivity and a smaller stroke.     

An enhanced base isolation system equipped with optimal tuned mass damper inerter (TMDI)

In seismic base isolation, most of the earthquake‐induced displacement demand is concentrated at the isolation level, thereby the base‐isolation system undergoes large displacements. In an attempt to reduce such displacement demand, this paper proposes an enhanced base‐isolation system incorporating the inerter, a 2‐terminal flywheel device whose generated force is proportional to the relative acceleration between its terminals. The inerter acts as an additional, apparent mass that can be even 200 times higher than its physical mass. When the inerter is installed in series with spring and damper elements, a lower‐mass and more effective alternative to the traditional tuned mass damper (TMD) is obtained, ie, the TMD inerter (TMDI), wherein the device inertance plays the role of the TMD mass. By attaching a TMDI to the isolation floor, it is demonstrated that the displacement demand of base‐isolated structures can be significantly reduced. Due to the stochastic nature of earthquake ground motions, optimal parameters of the TMDI are found based on a probabilistic framework. Different optimization procedures are scrutinized. The effectiveness of the optimal TMDI parameters is assessed via time history analyses of base‐isolated multistory buildings under several earthquake excitations; a sensitivity analysis is also performed. The enhanced base‐isolation system equipped with optimal TMDI attains an excellent level of vibration reduction as compared to the conventional base‐isolation scheme, in terms not only of displacement demand of the base‐isolation system but also of response of the isolated superstructure (eg, base shear and interstory drifts); moreover, the proposed vibration control strategy does not imply excessive stroke of the TMDI.     

Optimal design and seismic performance of tuned mass damper inerter (TMDI) for structures with nonlinear base isolation systems

The tuned mass damper inerter (TMDI) couples the classical tuned mass damper (TMD) with an inerter, a mechanical device whose generated force is proportional to the relative acceleration between its terminals, thus providing beneficial mass‐amplification effects. This paper deals with a dynamic layout in which the TMDI is installed below the isolation floor of base‐isolated structures in order to enhance the earthquake resilience and reduce the displacement demand. Unlike most of the literature studies that assumed a linearized behavior of the isolators, the aim of this paper is to investigate the effectiveness of the TMDI while accounting for the nonlinearity of the isolators. Two nonlinear constitutive behaviors are considered, a Coulomb friction model and a Bouc‐Wen hysteretic model, representative of friction pendulum and of lead‐rubber‐bearing isolators, respectively. Optimal design is based on the stochastic dynamic analysis of the system, by modeling the base acceleration as a Kanai‐Tajimi filtered stationary random process and resorting to the stochastic linearization technique to handle the nonlinear terms. Different tuning criteria based on displacement, acceleration, and energy‐based performance indices are defined, and their implications in a design process are discussed. It is proven that the improved robustness of the TMDI reduces its performance sensitivity to the tuning frequency and to the earthquake frequency content, which are well‐known shortcomings of TMD‐like systems. This important feature makes the TMDI particularly suitable for nonlinear base‐isolated structures that are affected by unavoidable uncertainties in the isolators' properties and that may experience changes of isolators effective stiffness depending on the excitation level.     

Second‐mode tuned mass dampers in base‐isolated structures for reduction of floor acceleration

To reduce floor acceleration of base‐isolated structures under earthquakes, a tuned mass damper (TMD) system installed on the roof is studied. The optimal tuning parameters of the TMD are analyzed for linear base isolation under a generalized ground motion, and the performance of the TMD is validated using a suite of recorded ground motions. The simulation shows that a TMD tuned to the second mode of a base‐isolated structure reduces roof acceleration more effectively than a TMD tuned to the first mode. The reduction ratio, defined as the maximum roof acceleration with the TMD relative to that without the TMD, is approximately 0.9 with the second‐mode TMD. The higher effectiveness of the second‐mode TMD relative to the first‐mode TMD is attributed primarily to the unique characteristics of base isolation, ie, the relatively long first‐mode period and high base damping. The modal acceleration of the second mode is close to or even higher than that of the first mode in base‐isolated structures. The larger TMD mass ratio and lower modal damping ratio of the second‐mode TMD compared to the first‐mode TMD increases its effect on modal acceleration reduction. The reduction ratio with the second‐mode TMD improves to 0.8 for bilinear base isolation. Because of the detuning effect caused by the change in the first‐mode period in bilinear isolation, the first‐mode TMD is ineffective in reducing roof acceleration. Additionally, the displacement experienced by the second‐mode TMD is considerably smaller than that of the first‐mode TMD, thereby reducing the installation space for the TMD.     

Development of a tunable friction pendulum system for semi‐active control of building structures under earthquake ground motions

The Friction Pendulum System (FPS) isolator is commonly used as a base isolation system in buildings. In this paper, a new tunable FPS (TFPS) isolator is proposed and developed to act as a semi‐active control system by combining the traditional FPS and semi‐active control concept. Theoretical analysis and physical tests were carried out to investigate the behavior of the proposed TFPS isolator. The experimental and theoretical results were in good agreement, both suggesting that the friction force of the TFPS isolator can be tuned to achieve seismic isolation of the structure. A series of numerical simulations of a base‐isolated structure equipped with the proposed TFPS isolator and subjected to earthquake ground motions were also conducted. In the analyses, the linear quadratic regulator (LQR) method was adopted to control the friction force of the proposed TFPS, and the applicability and effectiveness of the TFPS in controlling the structure's seismic responses were investigated. The simulation results showed that the TFPS can reduce the displacement of the isolation layer without significantly increasing the floor acceleration and inter‐story displacement of the superstructure, confirming that the TFPS can effectively control a base‐isolated structure under earthquake ground motions.     

Evaluation of a passive gap damper to control displacements in a shaking test of a seismically isolated three‐story frame

Recent studies have indicated uncertainty about the performance limit states of seismically isolated buildings in very large earthquakes, especially if the isolator displacement demands exceed the seismic gap and induce pounding. Previous research has shown the benefit of providing phased supplemental damping that does not affect the isolation system response in a design event. A phased passive control device, or gap damper, was designed, fabricated, and experimentally evaluated during shake table testing of a quarter scale base‐isolated three‐story steel frame building. Identical input motions were applied to system configurations without a gap damper and with a gap damper, to directly assess the influence of the gap damper on displacement and acceleration demands. The gap damper was observed to reduce displacement demands by up to 15% relative to the isolated system without the gap damper. Superstructure floor accelerations increased substantially because of damper activation, but were limited to a peak of about 1.18 g. The gap damper reduces displacement most effectively if the ground motion contains one or more of the following characteristics: the spectral displacement increases with increasing period near the effective period of the isolation system, the motion is dominated by a single large pulse rather than multiple cycles at a consistent intensity, and the motion has a dominant component aligned with a major axis of the structure. Copyright © 2016 John Wiley & Sons, Ltd.     

Particle swarm optimization of TMD by non‐stationary base excitation during earthquake

There are many traditional methods to find the optimum parameters of a tuned mass damper (TMD) subject to stationary base excitations. It is very difficult to obtain the optimum parameters of a TMD subject to non‐stationary base excitations using these traditional optimization techniques. In this paper, by applying particle swarm optimization (PSO) algorithm as a novel evolutionary algorithm, the optimum parameters including the optimum mass ratio, damper damping and tuning frequency of the TMD system attached to a viscously damped single‐degree‐of‐freedom main system subject to non‐stationary excitation can be obtained when taking either the displacement or the acceleration mean square response, as well as their combination, as the cost function. For simplicity of presentation, the non‐stationary excitation is modeled by an evolutionary stationary process in the paper. By means of three numerical examples for different types of non‐stationary ground acceleration models, the results indicate that PSO can be used to find the optimum mass ratio, damper damping and tuning frequency of the non‐stationary TMD system, and it is quite easy to be programmed for practical engineering applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Application of semi‐active tuned mass dampers to base‐excited systems

A continuously variable semi‐active damper is used in a tuned mass damper (TMD) to reduce the level of vibration of a single‐degree‐of‐freedom system subjected to harmonic base excitations. The ground hook dampers as have been used in the auto‐industry are being studied here. Using these dampers a new class of tuned mass dampers, named as ground hook tuned mass dampers (GHTMD) is being introduced. In order to generalize the design properties of the GHTMDs, they are defined in terms of non‐dimensional parameters. The optimum design parameters of GHTMDs for lightly damped systems are obtained based on the minimization of the steady‐state displacement response of the main mass. These parameters are computed for different mass ratios and main system damping ratios. Frequency responses of the resulting systems are compared to that of equivalent TMDs using passive dampers. In addition, other characteristics of this system as compared to the passive TMDs are discussed. A design guide to obtain the optimum parameters of GHTMD using the developed diagrams in this paper based on non‐dimensional values is presented. Copyright © 2001 John Wiley & Sons, Ltd.     

Study on effects of damping in laminated rubber bearings on seismic responses for a ⅛ scale isolated test structure

The effects of damping in various laminated rubber bearings (LRB) on the seismic response of a ?‐scale isolated test structure are investigated by shaking table tests and seismic response analyses. A series of shaking table tests of the structure were performed for a fixed base design and for a base isolation design. Two different types of LRB were used: natural rubber bearings (NRB) and lead rubber bearings (LLRB). Three different designs for the LLRB were tested; each design had a different diameter of lead plug, and thus, different damping values. Artificial time histories of peak ground acceleration 0.4g were used in both the tests and the analyses. In both shaking table tests and analyses, as expected, the acceleration responses of the seismically isolated test structure were considerably reduced. However, the shear displacement at the isolators was increased. To reduce the shear displacement in the isolators, the diameter of the lead plug in the LLRB had to be enlarged to increase isolator damping by more than 24%. This caused the isolator stiffness to increase, and resulted in amplifying the floor acceleration response spectra of the isolated test structure in the higher frequency ranges with a monotonic reduction of isolator shear displacement. Copyright © 2002 John Wiley & Sons, Ltd.