首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
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.  相似文献   

2.
This paper investigates the dynamic behavior and the seismic effectiveness of a non‐conventional Tuned Mass Damper (TMD) with large mass ratio. Compared with conventional TMD, the device mass is increased up to be comparable with the mass of the structure to be protected, aiming at a better control performance. In order to avoid the introduction of an excessive additional weight, masses already present on the structure are converted into tuned masses, retaining structural or architectural functions beyond the mere control function. A reduced order model is introduced for design purposes and the optimal design of a large mass ratio TMD for seismic applications is then formulated. The design method is specifically developed to implement High‐Damping Rubber Bearings (HDRB) to connect the device mass to the main structure, taking advantage of combining stiffness and noticeable damping characteristics. Ground acceleration is modeled as a Gaussian random process with white noise power spectral density. A numerical searching technique is used to obtain the optimal design parameter, the frequency ratio alpha, which minimizes the root‐mean‐square displacement response of the main structure. The study finally comprises shaking table tests on a 1:5 scale model under a wide selection of accelerograms, both artificial and natural, to assess the seismic effectiveness of the proposed large mass ratio TMD. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

3.
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.  相似文献   

4.
Inter‐story isolation, an effective strategy for mitigating the seismic risk of both new and existing buildings, has gained more and more interest in recent years as alternative to base isolation, whenever the latter results to be impractical, technically difficult or uneconomic. As suggested by the name, the technique consists in inserting flexible isolators at floor levels other than the base along the height of a multi‐story building, thus realizing a non‐conventional Tuned Mass Damper (TMD). Consistent with this, an optimal design methodology is developed in the present paper with the objective of achieving the global protection of both the structural portions separated by the inter‐story isolation system, that is, the lower portion (below the isolation system) and the isolated upper portion (above the isolation system). The optimization procedure is formulated on the basis of an energy performance criterion that consists in maximizing the ratio between the energy dissipated in the isolation system and the input energy globally transferred to the entire structure. Numerical simulations, performed under natural accelerograms with different frequency content and considering increasing isolation levels along the height of a reference frame structure, are used to investigate the seismic performance of the optimized inter‐story isolation systems. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
Liquid motions in shallow Tuned Liquid Dampers (TLDs) with rectangular, circular, and annular tanks, subject to harmonic base excitation, are measured experimentally. Using a Single-Degree-of-Freedom (SDOF) Tuned Mass Damper (TMD) analogy, equivalent mass, stiffness and damping of the TLD are calibrated from the experimental results. These parameters are functions of the TLD base amplitude. Some important properties of the TLD are discussed on the basis of these results.  相似文献   

6.
A variant type of tuned mass damper (TMD) termed as ‘non‐traditional TMD (NTTMD)’ is recently proposed. Mainly focusing on the employment of TMD for seismic response control, especially for base‐isolated or high‐rise structures, this paper aims to derive design formulae of NTTMDs based on two methodologies with different targets. One is the fixed points theory with the performance index set as the maximum magnitude of the frequency response function of the relative displacement of the primary structure with respect to the ground acceleration, and the other is the stability maximization criterion (SMC) to make the free vibration of the primary structure decay in the minimum duration. Such optimally designed NTTMDs are compared with traditional TMDs by conducting both numerical simulations and experiments. The optimum‐designed NTTMDs are demonstrated to be more effective than the optimum‐designed traditional TMDs, with smaller stroke length required. In particular, the effectiveness of the TMDs combined with a base‐isolated structure is investigated by small‐scale model experimental tests subjected to a time scaled long period impulsive excitation, and it is demonstrated that the SMC‐based NTTMD can suppress structural free vibration responses in the minimum duration and requires much smaller accommodation space. Additionally, a small‐scale shaking table experiment on a high‐rise bending model attached with a SMC‐based NTTMD is conducted. This study indicates that NTTMD has a high potential to apply to seismic response control or retrofit of structures such as base‐isolated or central column‐integrated high‐rise structures even if only a limited space is available for accommodating TMDs. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

7.
This paper proposes the use of a novel type of passive vibration control system to reduce vibrations in civil engineering structures subject to base excitation. The new system is based on the inerter, a device that was initially developed for high‐performance suspensions in Formula 1 racing cars. The principal advantage of the inerter is that a high level of vibration isolation can be achieved with low amounts of added mass. This feature makes it an attractive potential alternative to traditional tuned mass dampers (TMDs). In this paper, the inerter system is modelled inside a multi‐storey building and is located on braces between adjacent storeys. Numerical results show that an excellent level of vibration reduction is achieved, potentially offering improvement over TMDs. The inerter‐based system is compared to a TMD system by using a range of base excitation inputs, including an earthquake signal, to demonstrate how the performance could potentially be improved by using an inerter instead of a TMD. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

8.
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.  相似文献   

9.
Multiple tuned mass dampers (MTMD) consisting of many tuned mass dampers (TMDs) with a uniform distribution of natural frequencies are taken into consideration for attenuating undesirable vibration of a structure under the ground acceleration. A study is conducted to search for the preferable MTMD which performs better and is easily manufactured from the five available models (i.e. MTMD‐1 – MTMD‐5), which comprise various combinations of the stiffness, mass, damping coefficient and damping ratio in the MTMD. The major objective of the present study then is to evaluate and compare the control performance of these five models. The structure is represented by its mode‐generalized system in the specific vibration mode being controlled by adopting the mode reduced‐order approach. The optimum parameters of the MTMD‐1 – MTMD‐5 are investigated to reveal the influence of the important parameters on their effectiveness and robustness using a numerical searching technique. The parameters include the frequency spacing, average damping ratio, tuning frequency ratio, mass ratio and total number. The criteria selected for the optimum searching are the minimization of the maximum value of the displacement dynamic magnification factor (DDMF) and that of the acceleration dynamic magnification factor (ADMF) of the structure with the MTMD‐1 – MTMD‐5 (i.e. Min.Max.DDMF and Min.Max.ADMF). It is demonstrated that the optimum MTMD‐1 and MTMD‐4 yield approximately the same control performance, and offer higher effectiveness and robustness than the optimum MTMD‐2, MTMD‐3, and MTMD‐5 in reducing the displacement and acceleration responses of structures. It is further demonstrated that for both the best effectiveness and robustness and the simplest manufacturing, it is preferable to select the optimum MTMD‐1. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

10.
A new method to design multiple tuned mass dampers (multiple TMDs) for minimizing excessive vibration of structures has been developed using a numerical optimizer. It is a very powerful method by which a large number of design variables can be effectively handled without imposing any restriction before the analysis. Its framework is highly flexible and can be easily extended to general structures with different combinations of loading conditions and target controlled quantities. The method has been used to design multiple TMDs for SDOF structures subjected to wide‐band excitation. Some novel results have been obtained. To reduce displacement response of the structure, the optimally designed multiple TMDs have distributed natural frequencies and distinct damping ratios at low damping level. The obtained optimal configuration of TMDs was different from the earlier analytical solutions and was proved to be the most effective. A robustness design of multiple TMDs has also been presented. Robustness is defined as the ability of TMDs to function properly despite the presence of uncertainties in the parameters of the system. Numerical examples of minimizing acceleration structural response have been given where the system parameters are uncertain and are modeled as independent normal variates. It was found that, in case of uncertainties in the structural properties, increasing the TMD damping ratios along with expanding the TMD frequency range make the system more robust. Meanwhile, if TMD parameters themselves are uncertain, it is necessary to design TMDs for higher damping ratios and a narrower frequency range. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

11.
Various types of passive control systems have been used to suppress the seismic response of structures in recent years. Among these systems, Tuned Liquid Column Dampers （TLCDs） dissipate the input earthquake energy by combining the effects of the movement of the liquid mass in the container, the restoring force on the liquid due to the gravity loads and the damping due to the liquid movement through orifices. In this study, the effects of seismic excitation characteristics such as frequency content and soil condition on the seismic performance of TLCDs are investigated using nonlinear time-history analyses. In this regard, among the past earthquake ground motion records of Iran, 16 records with different parameters were selected. In the structural model developed, the attached TLCD is simulated as a Tuned Mass Damper （TMD） having the same vibration period and damping ratio as the original TLCD. The numerical results show that the seismic excitation characteristics have a substantial role on the displacement reduction capability of TLCDs and they should be considered accordingly in the design of TLCDs.  相似文献   

12.
This study investigates the effect of nonlinear inertia on the dynamic response of an asymmetric building equipped with Tuned Mass Dampers (TMDs). In the field of structural engineering, many researchers have developed models to study the behavior of nonlinear TMDs, but the effect of nonlinear inertia has not received as much attention for asymmetric buildings. To consider nonlinear inertia, the equations of motion are derived in a local rotary coordinates system. The displacements and rotations of the modeled building and TMDs are defined by five-degree-of-freedom (5-DOFs). The equations of motion are derived by using the Lagrangian method. Also in the proposed nonlinear model, the equations of motion are different from a conventional linear model. In order to compare the response of the proposed nonlinear model and a conventional linear model, numerical examples are presented and the response of the modeled buildings are derived under harmonic and earthquake excitations. It is shown that if the nonlinear inertia is considered, the response of the modeled structures changes and the conventional linear approach cannot adequately model the dynamic behavior of the asymmetric buildings which are equipped with TMDs.  相似文献   

13.
Analytical results are developed for vibration control of structures with one or more Tuned Mass Dampers (TMDs). The input is a harmonic load with a range of possible frequencies. The control objective is to reduce the maximum amplitude of the structural response. Perturbation theory is used with three sets of small parameters: the ratio of TMD and structural modal masses, the damping of the system, and the differences between the structural and loading frequencies. It is shown analytically that for structures with widely spaced natural frequencies, the response can be approximated accurately by the response of the well-known single-mode structure/TMD system. For structures with p closely spaced natural frequencies, more general analytical results are developed to describe the coupling between the motions of the p modes of the structure and the multiple TMDs. The results show that at least p TMDs with properly placed attachments to the structure are necessary to control the response. If fewer TMDs are used, the maximum frequency response has a lower bound which is independent of the properties of the TMDs. The TMD placement is shown to be always important, regardless of the spacing of the structure's natural frequencies. The results are illustrated for both lumped-mass and continuous structures.  相似文献   

14.
In this paper, the effectiveness of different design solutions for tuned mass dampers (TMD) applied to high‐rise cross‐laminated (X‐Lam) timber buildings as a means to reduce the seismic accelerations was investigated. A seven‐storey full‐scale structure previously tested on shaking table was used as a reference. The optimal design parameters of the TMDs, i.e. damping and frequency ratios, were determined by using a genetic algorithm on a simplified model of the reference structure, composed by seven masses each representing one storey. The optimal solutions for the TMDs were then applied to a detailed finite element model of the seven‐storey building, where the timber panels were modelled with shell elements and the steel connectors with linear spring. By comparing the numerical results of the building with and without multiple TMDs, the improvement in seismic response was assessed. Dynamic time‐history analyses were carried out for a set of seven natural records, selected in accordance with Eurocode 8, on the simplified model, and for Kobe earthquake ground motion on the detailed model. Results in terms of acceleration reduction for different TMD configurations show that the behaviour of the seven‐storey timber building can be significantly improved, especially at the upper storeys. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
高层建筑利用TLD减震的实例计算   总被引：6，自引：2，他引：4  
本文进行了高层建筑利用调频液体阻尼器（TLD）减震的实例计算。计算结果表明,对高层建筑而言,同时控制结构多振型反应比只控制结构第一振型反应效果好。  相似文献   

16.
基础隔震技术广泛应用于建筑结构以减轻结构的地震响应.值得注意的是,在隔震体系中减小主结构的加速度响应是以牺牲隔震器变形为代价的.调谐惯容系统(TID)和隔震器组成的混合隔震体系可减小隔震层的位移响应.与传统调谐质量阻尼器(TMD)结构类似,TID 由惯容、调谐弹簧和阻尼元件组成.因此,可直接利用 TMD减震系统的设计公式来确定 TID 的最优参数.首先基于单自由度体系(SDOF)附加 TID的运动方程,推导分析两种 TID和 TMD设计公式,对两者设计公式的前提条件和适用性进行深入的探讨.其后,借助基础隔震体系的benchmark模型来检验设计 TID的可行性和有效性.数值模拟结果表明,在不增加主结构绝对加速度响应的情况下, TID能够显著减小基础隔震结构的位移响应和基底剪力.  相似文献   

17.
Floor isolation system (FIS) achieving very small floor accelerations has been used to ensure human comfortability or protect important equipments in buildings. Tuned mass damper (TMD) with large mass ratios has been demonstrated to be robust with respect to the changes in structural properties. This paper presents the concept of a TMD floor vibration control system, which takes advantages of both the FIS and TMD. Such a system is called ‘TMD floor system’ herein. The TMD floor system (TMDFS) in which building floors serve as TMDs can achieve large mass ratio without additional masses. Furthermore, multiple TMD floors installed in a building can control multimode vibrations. Then, an optimal design process, where the objective function is set as the maximum magnitude of the frequency response functions of inter‐storey drifts, is proposed to determine the TMD floor parameters. Additionally, the multimode approach is applied to determine the optimal locations of TMD floors if not all of the floors in a building can serve as TMDs. In addition to the numerical simulations, a scaled model shaking table experiment is also conducted. Both the numerical and experimental results show that the absolute accelerations of the TMD floors are smaller than those of the main structural storeys, which indicates the TMDFS maintains the merit of FIS while greatly reducing seismic responses of main structures. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

18.
The effectiveness of Tuned Mass Dampers (TMD) on buildings subjected to moderate and high-intensity motions is analysed. First, the response of a 22-storey four-bay reinforced concrete non-linear frame with a TMD is studied for motions with different intensities. Several values of the relevant parameters are assumed in the analyses. Then, equivalent single-degree-of-freedom systems with TMDs and without them are defined and analysed under the action of ground motions with intensities associated with different return intervals at the site where the structures are located. Vulnerability curves for the systems are obtained based on the probabilities of reaching two different performance limit states. The expected annual rate of exceedance of each limit state is calculated. The results show that the effectiveness of TMDs is higher for systems with small non-linearity produced by small and moderate earthquakes, than for systems with high non-linear behaviour, generally associated with high-intensity motions. Some recommendations about the applicability of TMD are given. Copyright © 1999 John Wiley & Sons Ltd.  相似文献   

19.
Structural vibration control using active or passive control strategy is a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high wind gusts. Both the active and passive control systems have their limitations. The passive control system has limited capability to control the structural response whereas the active control system depends on external power. The power requirement for active control of civil engineering structures is usually quite high. Thus, a hybrid control system is a viable solution to alleviate some of the limitations. In this paper a multi‐objective optimal design of a hybrid control system for seismically excited building structures has been proposed. A tuned mass damper (TMD) and an active mass driver (AMD) have been used as the passive and active control components of the hybrid control system, respectively. A fuzzy logic controller (FLC) has been used to drive the AMD as the FLC has inherent robustness and ability to handle the non‐linearities and uncertainties. The genetic algorithm has been used for the optimization of the control system. Peak acceleration and displacement responses non‐dimensionalized with respect to the uncontrolled peak acceleration and displacement responses, respectively, have been used as the two objectives of the multi‐objective optimization problem. The proposed design approach for an optimum hybrid mass damper (HMD) system, driven by FLC has been demonstrated with the help of a numerical example. It is shown that the optimum values of the design parameters of the hybrid control system can be determined without specifying the modes to be controlled. The proposed FLC driven HMD has been found to be very effective for vibration control of seismically excited buildings in comparison with the available results for the same example structure but with a different optimal absorber. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

20.
The Tuned Liquid Damper (TLD) is modelled numerically as an equivalent tuned mass damper with non-linear stiffness and damping. These parameters are derived from extensive experimental results described in References 1 and 2. This Non-linear Stiffness and Damping (NSD) model captures the behaviour of the TLD system adequately under a variety of loading conditions. In particular, the NSD model incorporates the stiffness hardening property of the TLD under large amplitude excitation. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号