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1.
The main intention of the present study is to reduce wind, wave, and seismic induced vibrations of jackettype offshore wind turbines (JOWTs) through a newly developed vibration absorber, called tuned liquid column gas damper (TLCGD). Using a Simulink-based model, an analytical model is developed to simulate global behavior of JOWTs under different dynamic excitations. The study is followed by a parametric study to explore efficiency of the TLCGD in terms of nacelle acceleration reduction under wind, wave, and earthquake loads. Study results indicate that optimum frequency of the TLCGD is rather insensitive to excitation type. In addition, while the gain in vibration control from TLCGDs with higher mass ratios is generally more pronounced, heavy TLCGDs are more sensitive to their tuned frequency such that ill-regulated TLCGD with high mass ratio can lead to destructive results. It is revealed that a well regulated TLCGD has noticeable contribution to the dynamic response of the JOWT under any excitation. 相似文献
2.
This paper presents a theoretical investigation on the performance of multiple‐tuned liquid column dampers (MTLCD) for reducing torsional vibration of structures in comparison with single‐tuned liquid column dampers (STLCD). The analytical model is first developed for torsional vibration of a structure with an MTLCD under either harmonic excitation or white noise excitation. The experimental results are then used to verify the analytical model for coupled MTLCD‐structure systems under harmonic excitation. The performance of an MTLCD and its beneficial parameters for achieving the maximum torsional response reduction to white noise excitation are finally investigated through an extensive parametric study in terms of the distance from the centre line of the MTLCD to the rotational axis of the structure, the ratio of the horizontal length to the total length of liquid column, frequency bandwidth, head‐loss coefficient, the number of TLCD units in an MTLCD, frequency‐turning ratio and the spectral level of excitation moment. The results show that there is an optimal head‐loss coefficient and an optimal frequency bandwidth for an MTLCD to achieve the maximum torsional response reduction. It is also demonstrated that the sensitivity of an optimized MTLCD to the frequency‐tuning ratio is less than that of an optimized STLCD, and it can be further improved by increasing the bandwidth but at the cost of less torsional vibration reduction. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
3.
Design parameters for single- and multiple-tuned liquid column dampers for reducing the response of structures to seismic excitations are presented. A deterministic analysis is carried out using 72 earthquake ground motion records to determine the tuning ratio, tube width to liquid length ratio, and head loss coefficient corresponding to a given mass ratio for single-tuned liquid column dampers. A similar analysis is performed to determine the central tuning ratio, tuning bandwidth, and grouping of dampers for multiple-tuned liquid column dampers. The study indicates that by properly selecting the design parameters, single- and multiple-tuned liquid column dampers can reduce the response of structures to seismic excitation by up to 45 per cent. Design examples using single- and multiple-tuned liquid column dampers in a bridge and a ten-storey building are presented to illustrate how the parameters are selected and to demonstrate the performance of the devices under different ground excitations. The response of several structures with tuned liquid column dampers is compared with that using tuned mass dampers where it is shown that both devices result in comparable reductions in the response. © 1998 John Wiley & Sons, Ltd. This paper was produced under the auspices of the U.S. Government and it is therefore not subject to copyright in the U.S. 相似文献
4.
新型形状记忆合金阻尼器的试验研究 总被引：23，自引：5，他引：23
本文在对形状记忆合金(SMA)的力学性能研究的基础上，设计和制造出一种性能良好的SMA阻尼器，介绍了其工作原理及有关试验结果，将该阻尼器安装在斜拉桥模型上，进行了斜拉桥模型振动试验。试验结果表明该阻尼器的耗能效果明显，在工程结构振动控制方面具有比较好的应用前景。 相似文献
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In this study, several mass dampers were designed and fabricated to suppress the seismic responses of a ¼‐scale three‐storey building structure. The dynamic properties of the dampers and structure were identified from free and forced vibration tests. The building structure with or without the dampers was, respectively, tested on a shake table under the white noise excitation, the scaled 1940 El Centro earthquake and the scaled 1952 Taft earthquake. The dampers were placed on the building floors using the sequential procedure developed by the authors in previous studies. Experimental results indicated that the multiple damper system is substantially superior to a single tuned mass damper in mitigating the floor accelerations even though the multiple dampers are sub‐optimal in terms of tuning frequency, damping and placement. These results validated the sequential procedure for placement of the multiple dampers. The structure was also analysed numerically based on the shake table excitation and the identified structure and damper parameters for all test cases. Numerical and experimental results are in good agreement, validating the dynamic properties identified. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
6.
黏滞阻尼器对拉索参数振动的控制分析 总被引：1，自引：0，他引：1
提出采用黏滞阻尼器对拉索参数振动进行控制,建立了黏滞阻尼器控制拉索参数振动的运动方程。从频域和时域以及起振幅值等角度,研究了最优黏滞阻尼器对不同垂度拉索参数振动的控制效果;此外,还研究了最优黏滞阻尼器安装位置对拉索参数振动控制效果的影响。研究表明,黏滞阻尼器可以有效控制拉索的参数振动,控制效果与拉索的激励幅值、最优阻尼器的安装位置和斜拉索的垂度有关。激励幅值越大,控制效果一般越差;最优阻尼器的安装位置越靠近跨中,则控制效果越好;黏滞阻尼器对大垂度拉索的控制效果不及对小垂度拉索的控制效果。 相似文献
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本文采用Spencer提出的MR模型,对斜拉索和MR阻尼器组成的系统进行了动力分析,考察了MR阻尼器型号、安装位置、施加的电压以及斜拉索基频(张力、索长、质量)、激励荷载(类型、频率、大小)等各种因素对斜拉索共振峰频率漂移的影响。进而对钱江三桥南岸154m长的斜拉索进行了现场试验。斜拉索自由振动的衰减信号通过阶跃激励的方法获得,经小波变换、Hilbert变换识别出系统的共振峰频率,并与斜拉索在安装油阻尼器和无阻尼器两种情况进行了比较。计算了杭州湾大桥330m长的索在被动控制、半主动控制下的各阶共振峰频率。研究表明,斜拉索在安装MR阻尼器后共振峰频率略微增大。其影响程度比安装油阻尼器时要大。因此MR阻尼器的制振效果除主要来自耗能外,还有部分来自调频作用。 相似文献
9.
This paper reports on the results of a study conducted on tanks partially filled with water, representing tuned liquid dampers (TLD), subjected to both 1D and 2D horizontal excitations. The sloshing response of the water in the tank is characterized by the free surface motion, the resulting base shear force, and evaluation of the energy dissipated by the sloshing water. A 1D non‐linear flow model capable of simulating a TLD equipped with damping screens is employed to model a 2D TLD. Application of this particular model requires the assumption that the response is decoupled and can be treated as the summation of two independent 1D TLDs. Results from the non‐linear flow model are compared with the 2D experimental shake table test results leading to a validation of the decoupled response assumption. This attractive decoupled response property allows square and rectangular tanks to be used as 2D TLDs, which can simultaneously reduce the dynamic response of a structure in two perpendicular modes of vibration. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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新型SMA耗能器及结构地震反应控制试验研究 总被引：27，自引：4，他引：27
利用NiTi合金丝的超弹性性能，本文提出了两种新型SMA被动耗能器，分别称之为拉伸型SMA耗能器和剪刀型SMA耗能器。通过对耗能器的构造设计，安装在耗能器中的NiTi丝始终处于受拉状态，避免了合金丝在结构振动过程中受压屈曲。文中阐述了拉伸型SMA耗能器和剪刀型SMA耗能器的构造及工作原理，并将其安装在模型结构上进行了地震模拟振动台试验，验证了新型SMA耗能器的减振效果。 相似文献
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相对传统结构,自复位墙结构在地震作用下具有更大的变形能力且几乎无残余位移,但其耗能能力较弱,需采用附加阻尼来增加整体耗能.目前,金属阻尼器已广泛用于自复位墙结构,其可显著减小结构大震下的地震响应,但小震下的位移和加速度减震效果不佳.因此,将小变形下即可耗能的黏弹性阻尼器应用于自复位墙结构中.设计一幢10层自复位墙结构,分别采用黏弹性阻尼器和 U 型金属阻尼器作为附加耗能构件,通过弹塑性时程分析对比采用两种耗能机制的结构地震响应.结果表明,黏弹性阻尼器可显著减小自复位墙结构在小震下的位移和加速度响应;U 型金属阻尼器在中震下开始耗能,在大震和巨震下,其减震效果会超越黏弹性阻尼器.因此,为进一步优化自复位墙结构在不同水准地震作用下的抗震性能,建议结合阻尼器的特点进行合理设计. 相似文献
13.
Lyan‐Ywan Lu 《地震工程与结构动力学》2004,33(5):647-668
In this paper a predictive control method especially suitable for the control of semi‐active friction dampers is proposed. By keeping the adjustable slip force of a semi‐active friction damper slightly lower than the critical friction force, the method allows the damper to remain in its slip state throughout an earthquake of arbitrary intensity, so the energy dissipation capacity of the damper can be improved. The proposed method is formulated in a discrete‐time domain and cast in the form of direct output feedback for easy control implementation. The control algorithm is able to produce a continuous and smooth slip force for a friction damper and thus avoid exerting the high‐frequency structural response that usually exists in structures with conventional friction dampers. Using a numerical study, the control performance of a multiple degrees of freedom (DOF) structural system equipped with passive friction dampers and semi‐active dampers controlled by the proposed method are compared. The numerical case shows that by merely using a single semi‐active friction damper and a few sensors, the proposed method is able to achieve better acceleration reduction than the case using multiple passive dampers. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
Henry C.Huang 《地震工程与工程振动(英文版)》2009,8(4):521-536
After nearly a decade of application and investigation,a motion amplifi cation device with viscous dampers for energy dissipation has been recognized as an effective solution to mitigate wind or seismic excitation,especially for stiff structural systems.As a result of compensation of amplifi ed motion,it has been proved that the effi ciency of viscous damper largely depends on the motion amplifi cation device confi guration,particularly for device stiffness.In this paper,a scissor-jack type of motion amplif... 相似文献
15.
Mehdi Setareh 《地震工程与结构动力学》2001,30(3):449-462
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
16.
This paper presents an experimental investigation on the performance of multiple‐tuned liquid column dampers (MTLCD) for reducing torsional vibration of structures in comparison with single‐tuned liquid column dampers (STLCD). A large structure model simulating its torsional vibration and several STLCDs and MTLCDs of different configurations are designed and constructed. A series of harmonically forced vibration tests are conducted to evaluate the effectiveness of MTLCDs in reducing torsional vibration of the structure and to assess the performance effects of various design parameters, which include the number of TLCD units in a MTLCD, the bandwidth of a MTLCD, the frequency tuning ratio and the moment excitation amplitude. An averaging method is also used to identify the head loss coefficients of STLCDs and MTLCDs in conjunction with the free vibration test technique. The experimental results show that the performance of a MTLCD is better than a STLCD with the same water volume in reducing the torsional vibration of structure. The performance sensitivity to frequency tuning ratio can be improved by using MTLCDs. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
17.
Rafael Ruiz Alexandros A. Taflanidis Diego Lopez-Garcia Christopher R. Vetter 《Bulletin of Earthquake Engineering》2016,14(3):943-970
The assessment of the effectiveness of mass dampers for the Chilean region within a multi-objective decision framework utilizing life-cycle performance criteria is considered in this paper. The implementation of this framework focuses here on the evaluation of the potential as a cost-effective protection device of a recently proposed liquid damper, called tuned liquid damper with floating roof (TLD-FR). The TLD-FR maintains the advantages of traditional tuned liquid dampers (TLDs), i.e. low cost, easy tuning, alternative use of water, while establishing a linear and generally more robust/predictable damper behavior (than TLDs) through the introduction of a floating roof. At the same time it suffers (like all other liquid dampers) from the fact that only a portion of the total mass contributes directly to the vibration suppression, reducing its potential effectiveness when compared to traditional tuned mass dampers. A life-cycle design approach is investigated here for assessing the compromise between these two features, i.e. reduced initial cost but also reduced effectiveness (and therefore higher cost from seismic losses), when evaluating the potential for TLD-FRs for the Chilean region. Leveraging the linear behavior of the TLD-FR a simple parameterization of the equations of motion is established, enabling the formulation of a design framework that beyond TLDs-FR is common for other type of linear mass dampers, something that supports a seamless comparison to them. This framework relies on a probabilistic characterization of the uncertainties impacting the seismic performance. Quantification of this performance through time-history analysis is considered and the seismic hazard is described by a stochastic ground motion model that is calibrated to offer hazard-compatibility with ground motion prediction equations available for Chile. Two different criteria related to life-cycle performance are utilized in the design optimization, in an effort to support a comprehensive comparison between the examined devices. The first one, representing overall direct benefits, is the total life-cycle cost of the system, composed of the upfront device cost and the anticipated seismic losses over the lifetime of the structure. The second criterion, incorporating risk-averse concepts into the decision making, is related to consequences (repair cost) with a specific probability of exceedance over the lifetime of the structure. A multi-objective optimization is established and stochastic simulation is used to estimate all required risk measures. As an illustrative example, the performance of different mass dampers placed on a 21-story building in the Santiago area is examined. 相似文献
18.
A tuned liquid damper (TLD), which consists of rigid tanks partially filled by liquid, is a type of passive control device relying upon liquid sloshing forces or moments to change the dynamical properties and to dissipate vibrational energy of a structure. An analytical non-linear model is proposed for a TLD using rectangular tanks filled with shallow liquid under pitching vibration, utilizing a shallow water wave theory. The model includes the linear damping of the sloshing liquid, which is an important parameter in the study of a TLD as it affects the efficiency of the TLD. Shaking table experiments were conducted for verification; good agreement between the analytical simulations and the experimental results was observed in a small excitation amplitude range. The simulations of TLD-structure interaction by using the proposed model show that the TLD can efficiently suppress resonant pitching vibration of a structure. It is also found that the effectiveness of a TLD for suppressing the pitching vibration depends not only on the mass of liquid in the TLD but also on the configuration of the liquid as well as upon the position where the TLD is located. If the configuration of the liquid, i.e. the liquid depth and the TLD tank size, is designed suitably, the TLD can have a large suppressing moment and can be very effective even with a small mass of liquid. 相似文献
19.
《地震工程与工程振动(英文版)》2015,(1)
This study proposes a novel mild steel damper with non-uniform vertical slits. The infl uence of different shapes of vertical slits of the core energy plate on the energy dissipation and buckling resistance capacities is analyzed. Based on the theoretical analysis, formulas of key parameters of the dampers, including the elastic lateral stiffness, shear bearing capacity and yield displacement, are derived. The effectiveness of the proposed damper is demonstrated through pseudo static tests on four 0.25-scale specimens. Performance of these dampers, i.e. cyclic deformation, stress distribution, energy dissipation capacity, etc., are presented and discussed. Using the numerical models of dampers calibrated through test data, earthquake time-history analyses were conducted, and it is observed that the dampers significantly reduce the seismic responses of the prototype frame and have a desirable energy dissipation capacity. 相似文献
20.
A series of large‐scale dynamic tests was conducted on a passively controlled five‐story steel building on the E‐Defense shaking table facility in Japan to accumulate knowledge of realistic seismic behavior of passively controlled structures. The specimen was tested by repeatedly inserting and replacing each of four damper types, that is, the buckling restrained braces, viscous dampers, oil dampers, and viscoelastic dampers. Finally, the bare steel moment frame was tested after removing all dampers. A variety of excitations was applied to the specimen, including white noise, various levels of seismic motion, and shaker excitation. System identification was implemented to extract dynamic properties of the specimen from the recorded floor acceleration data. Damping characteristics of the specimen were identified. In addition, simplified estimations of the supplemental damping ratios provided by added dampers were presented to provide insight into understanding the damping characteristics of the specimen. It is shown that damping ratios for the specimen equipped with velocity‐dependent dampers decreased obviously with the increasing order of modes, exhibiting frequency dependency. Damping ratios for the specimen equipped with oil and viscoelastic dampers remained constant regardless of vibration amplitudes, whereas those for the specimen equipped with viscous dampers increased obviously with an increase in vibration amplitudes because of the viscosity nonlinearity of the dampers. In very small‐amplitude vibrations, viscous and oil dampers provided much lower supplemental damping than the standard, whereas viscoelastic dampers could be very efficient. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献