Stochastic earthquake response control of structures by liquid column vibration absorber with uncertain bounded system parameters

The present work deals with optimum design of liquid column vibration absorber (LCVA) for seismic vibration control of structures characterized by uncertain system parameters. This involves optimization of the frequency and damping properties of LCVA considering uncertain properties of the structure and ground motion parameters. The study on optimum design of tuned mass damper system considering random system parameters is noteworthy. But, the same is not the case for liquid dampers. Moreover, though the probabilistic methods are powerful, the approach cannot be applied in many real situations when the required detailed information about uncertain parameters is limited. In such cases, the interval method is a viable alternative. With the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem under bounded uncertainty is transformed to appropriate deterministic optimization problems. This requires optimizing two separate objective functions correspond to a lower bound and an upper bound optimum solutions. A numerical study is performed to study the effect of system parameter uncertainty on the optimization of LCVA parameters and its response reduction efficiency. Though the efficiency is not completely eliminated, the advantage of the LCVA tends to reduce as the level of uncertainty increases. It is also seen that neglecting the effect of system parameter uncertainty may overestimate the damper performance.     

Wind-induced vibration control of long span cable-stayed bridges using multiple pressurized tuned liquid column dampers

This paper explores the possibility of using multiple pressurized tuned liquid column damper (MPTLCD) to reduce wind-induced vibration of long span cable-stayed bridges. By implementing a static pressure inside two sealed air chambers at two ends of a traditional tuned liquid column damper (TLCD), a pressurized tuned liquid column damper (PTLCD) is formed and its natural frequency can be adjusted by not only the length of its liquid column but also the pressure inside its two air chambers. This special feature of PTLCD in frequency tuning greatly facilitates its application to long span cable-stayed bridges for mitigating wind-induced multi-modes of vibration. To further enhance the robustness and effectiveness of PTLCD for vibration control, MPTLCDs are explored in this study. The finite element model of MPTLCD is developed and incorporated into the finite element model of a long span cable-stayed bridge for predicting the buffeting response of the coupled MPTLCD-bridge system in the time domain. The performance of MPTLCD for suppressing combined lateral and torsional vibration of a real long span cable stayed bridge is numerically assessed. The investigations show that the MPTLCD not only provides great flexibility for selecting liquid column length but also significantly reduces the lateral and torsional displacement responses of the long span bridge under wind excitation.     

Application of spherical tuned liquid damper in vibration control of wind turbine due to earthquake excitations

A spherical tuned liquid damper (TLD) is proposed as a cost‐effective method to reduce the earthquake‐induced vibration of wind turbines. A 1/20‐scale test model was designed to investigate its performance of controlling the structural vibration. A series of free and forced vibration experiments with different water depths in hemispherical containers were performed on the shaking table. Three measured ground acceleration‐time histories, including El Centro NS, El Centro EW and Tianjin EW, were selected to verify the effectiveness of spherical TLD in suppressing the earthquake‐induced vibration. The experimental results showed that the spherical TLD could effectively improve the damping capacity of the test model. The standard deviation of the dynamic response could be effectively reduced when the excitation frequency was approximately equal to its fundamental frequency. The liquid sloshing motion in containers was characterized by a highly nonlinear and complex nature. The effectiveness of spherical TLDs does not increase linearly as the mass of water in containers and is influenced greatly by the frequency components of earthquake excitations. For El Centro EW excitation, the standard deviations of the dynamic responses could be reduced more than 40% when the liquid mass was about 2% of the generalized mass. Copyright © 2015 John Wiley & Sons, Ltd.     

Earthquake vibration control of structures using hybrid mass liquid damper

A tuned liquid damper (TLD) is a passive vibration control device consisting of a rigid tank filled with water that relies on the sloshing of water inside it to dissipate energy. In a standard TLD configuration the TLD is connected rigidly to the top of the building structure. Earlier research has shown that the TLD is more effective when its base acceleration amplitude is larger, as it dissipates more energy through increased sloshing. This characteristic has been utilized to design this alternate TLD configuration. In this alternate TLD configuration, the TLD is rigidly attached to a secondary mass that is attached to the primary structure through a spring system. This alternate configuration is, thus, defined as a hybrid mass liquid damper (HMLD). For particular values of the secondary spring’s flexibility, the motion of the secondary structure is in phase with that of the primary structure and the TLD base is subjected to a large amplitude acceleration that increases its effectiveness. It should be noted that when the secondary spring is rigid, the alternate and standard TLD configurations are identical for very small values of the secondary mass. It is seen that, for a given structure with HMLD there exists an optimum value of the secondary spring’s stiffness for which the HMLD effectiveness is maximum. An optimally designed HMLD configuration is shown to be more effective as a control device than the standard TLD configuration for both harmonic and broad-band earthquake motions.     

Structural vibration control using modified tuned liquid dampers

A tuned liquid damper (TLD) is a passive damper consisting of a solid tank filled with water that uses the water sloshing inside it to dissipate energy. The standard TLD configuration is where a TLD is connected rigidly to the top of the building. It has been popular as a control device for wind excitation. Earlier research has shown that the TLD behaviour is amplitude dependent, i.e. it is more effective when excitation amplitude is increased and more energy is dissipated due to sloshing. A modified TLD configuration is proposed here, where the TLD rests on an elevated platform that is connected to the top of the building through a rigid rod with a flexible rotational spring at its bottom. For particular values of the rotational spring flexibility, the rotational acceleration of the rod is in phase with the structure top acceleration and the TLD base is subjected to a large amplitude acceleration that increases its effectiveness. It should be noted that when the rotational spring is rigid, the modified and standard TLD configurations are identical. It is seen that, for aiven structure with modified TLD configuration, there exists an optimum value of the rotational spring stiffness for which the effectiveness of the modified TLD is maximum. Thus, it is seen that an optimally designed modified TLD configuration may be more effective as a structural control device than a standard TLD configuration, for both harmonic and broad-band earthquake motions.     

Optimizing parameters of tuned mass damper subjected to critical earthquake

Tuned mass damper (TMD) has been proposed as one of the vibration control methods for rehabilitation of buildings. Because the parameters of TMD can significantly affect the seismic performance of structures, many researches focused on finding the optimum parameters. Because earthquakes are random phenomena and future earthquakes in comparison with past earthquakes may be more destructive, the optimum design of TMD subjected to selected earthquakes can be nonconservative. Hence, the main contribution of this paper is to present the optimal design of TMD for the seismic vibration control of a structure subjected to a critical earthquake that produces the most severe response of a structure. In order to achieve this purpose, the parameters of TMD are optimized through minimizing the maximum displacement of the roof. First, three optimization methods are used to obtain the optimal parameters of TMD for a 10‐story shear building subjected to the critical earthquakes. Finally, the responses of the controlled and uncontrolled buildings such as the roof displacement, strokes, transfer function, and different forms of energy are compared. Results show that the optimum designs of TMD not only effectively reduce the roof displacement but also improve the seismic performance of the building.     

Efficient estimation of tuned liquid column damper inerter (TLCDI) parameters for seismic control of base-isolated structures

This paper presents an enhanced base-isolation (BI) system equipped with a novel passive control device composed of a tuned liquid damper and an inerter (TLCDI). With the aim of reducing the seismic response of BI systems, this contribution focuses on the design of the TLCDI providing analytical solutions for the optimal TLCDI parameters, easily implementable in the design phase. The effectiveness of the proposed approach in terms of seismic response reduction and computational gain is validated by comparison with classical numerical optimization techniques. The control performance of two different base-isolated TLCDI-controlled structures is assessed by employing real-ground motion records, and relevant comparisons with both uncontrolled base-isolated structures and equipped with a conventional TLCD are presented.     

调频减振系统和黏滞阻尼系统在超高层结构中风振控制性能的对比研究

超高层建筑中常用的风振控制措施主要包括调频减振系统和黏滞阻尼系统.系统地阐述了两种方案的基本原理、工程适用性以及参数取值,并结合实际项目较为全面地对比了其抗风性能.虽然调频减振系统在建筑功能的适应度上和施工可实施性上都存在一定的不足,但作为结构风振控制措施仍不失为一种可取方案.黏滞阻尼系统不但可以提升结构在风荷载下的舒...     

结构振动控制中金属型阻尼器的研究进展

对结构振动控制中的金属型阻尼器进行了总结,包括软钢阻尼器、铅阻尼器及形状记忆合金阻尼器,介绍了该研究方向最新的研究进展,并对工程结构振动控制中金属型阻尼器的发展前景提出了自己的见解。     

Mass ratio factor in control performance of optimum tuned liquid dampers

Tuned liquid dampers provide structure control with the help of the liquid mass in tanks that are attached to the structure. The mass ratio affects the optimum tuned liquid damper (TLD) parameters. This study examines the effect of mass ratio on the control performance of TLD devices in providing seismic control of structures with different damping ratios. For this purpose, TLD devices with different mass ratios were placed on two different single-story steel and reinforced concrete structure models, and their performance under earthquake excitation was investigated. TLD parameters for obtaining the optimum displacement level in the 0.5- and 1.0-s structure natural period for both structure types were optimized with the Jaya algorithm (JA), which is a metaheuristic algorithm. By using the optimum TLD parameters, the structural displacement and total acceleration values were obtained by the critical earthquake analysis. When the results are examined, it is understood that TLD mass increase from a 20% mass ratio for both structure types and selected structure periods does not have a significant effect on TLD control performance.     

附加PTMD风力发电机结构减振控制试验研究

通过开展附加颗粒调谐质量阻尼器(particle tuned mass damper, PTMD)风力发电机结构模型的自由振动试验和振动台试验，研究PTMD自身参数对其减振性能的影响规律，检验PTMD用于降低风力发电机结构不利振动的合理性与有效性，揭示随机激励下耦合系统的工作机理。借助自由振动试验研究了设计参数对PTMD减振性能的影响规律，初步确定了系统的参数配置。同时，通过地震波激励工况、风荷载激励工况和风-地震耦合荷载激励工况对风力发电机结构使用PTMD进行振动控制的合理性与有效性进行了检验，进一步揭示随机激励下耦合系统的减振机理。试验结果表明：颗粒-腔体质量比和频率比参数分别取值0.27和0.97时PTMD表现出较好的减振性能；3种随机激励下PTMD能够有效抑制风力发电机结构的动力响应，其中，El Centro波作用下，PTMD对结构顶部加速度和位移峰值响应的控制效果分别为5.52%和7.73%,而对均方根响应的控制效果则高达33.3%和32.08%。由此可见，PTMD对均方根响应的控制效果优于峰值响应。对比传统调谐质量阻尼器(TMD)结果可知，经合理设计的PTMD具有更佳的减振...     

Mechanism and optimum design of shared tuned mass damper for twin‐tower structures connected at the top by an isolated corridor

The concept of shared tuned mass damper (STMD) for twin towers linked by a sky corridor using flexible joints is proposed in this paper. The analytical expressions of the transform functions and random earthquake responses of the flexibly connected structures are derived using a three‐degrees‐of‐freedom model system. The seismic reduction mechanism of the STMD is revealed using comparative analysis between the structures with STMD and those connected using a viscoelastic damper. The effect of the nondimensional parameters such as the frequency ratio of the two primary structures, mass ratio, tuning frequency ratio of the corridor, and damping ratio of the passive control devices on the structural seismic response is investigated. Optimum parametric analysis is performed using the principle of minimizing the displacements of both towers, and the optimal parameter formulas are established. Numerical analysis is conducted to verify the control effectiveness of the connected multi‐degree‐of‐freedom system subjected to the El Centro earthquake ground motion. The results show that the earthquake responses of the towers can be effectively reduced if the parameters of the flexible connecting elements are appropriately selected for a certain corridor mass. Moreover, a remarkable seismic reduction effect can be achieved if the towers have similar dynamic properties.     

用于结构振动控制的MTMD设计模型及最优设计参数

多重调谐质量阻尼器(MTMD)是由许多频率成线性分布的调谐质量阻尼器组成。可能的系统参数组合形成5种MTMD模型(即MTMD-1～MTMD-5)。基于在基底加速度作用下具有一般MTMD时结构的位移传递函数，建立了MTMD1～MTMD-5位移动力放大系数(DDMF）的统一模式。利用DDMF和数值寻优技术得到了5种MTMD模型的最优设计参数。最优设计参数包括：最优频率间隔、最优阻尼比和最优调谐频率比。这些最优设计参数可为工程设计直接使用。数值分析表明：使用MTMD来控制结构的地震反应时，应同时选择MTMD-1和MTMD-5两种模型．经综合分析比较而确定。     

Experimental investigation on dynamic characterization and seismic control performance of a TLPD system

The tuned liquid damper (TLD) and particle damper (PD) have been used as effective passive vibration absorbers to suppress undesirable structural vibrations induced by dynamic loads such as earthquake and strong winds. In this paper, through an integrated use of the TLD and PD, a new damper system named the tuned liquid particle damper (TLPD) was developed. The dynamic characteristics of TLPD in terms of tuning conditions and transfer functions were investigated through a series of shaking table tests. Nonlinear behaviors of TLPD in the frequency domain were discussed, and a preliminary framework was applied in the design of a five‐story steel frame building model using shaking table tests. Testing results confirmed the workability of the preliminary design framework as the primary structure is subjected to earthquake loadings. Performances of different TLPD‐structure systems were summarized from these testing programs. One of observations is that the TLPD system worked as a modified TLD in this study. The testing programs provide proof‐of‐concept results for this proposed vibration absorber.     

新型隔震支座在网壳结构振动控制中的应用研究

将形状记忆合金(SM A)与普通叠层橡胶垫复合可以形成一种新型SM A-橡胶隔震支座.本文阐明了SM A-橡胶支座的工作机理,并建立了支座的理论模型.将设计的新型支座应用于空间网壳结构地震的被动控制,推导了支座隔震空间网壳结构的振动方程.最后,通过某双层柱面网壳结构地震响应的数值模拟考察了SM A-橡胶支座对网壳结构的减振效果.研究结果表明,新型SM A-橡胶支座较普通橡胶支座具有更好的隔震性能,可有效应用于网壳结构的振动控制.     

A hybrid structural control system using a tuned liquid damper to reduce the wind induced motion of a base isolated structure

This study investigates the use of a tuned liquid damper (TLD) as a cost effective method to reduce the wind induced vibrations of base isolated structures. The TLD is modelled as an equivalent linearized mechanical system in which the damping and natural frequency of the sloshing fluid are amplitude dependent quantities. The base isolated structure is represented using a modified form of the linearized Bouc-Wen model, which enables the behaviour of Stable Unbonded Fibre Reinforced Elastomeric Isolators (SU-FREIs) to be described. The TLD and base isolated structure are combined to form a system of coupled ordinary differential equations, the solution to which produces frequency response curves for the structure and TLD. A preliminary TLD design procedure is presented which allows the proper tank dimensions and damping screen properties to be established. The equivalent linearized mechanical model is validated using time simulations which account for the nonlinear behaviour of the structure and fluid. The models are found to be in excellent agreement. A TLD is found to be an effective means to control the wind induced vibration of a base isolated structure.     

日本建筑结构耗能减震研究和应用的若干新进展

介绍了日本在建筑结构耗能减震研究和应用方面取得的若干新进展，其中纳米结晶锌铝合金振动控制阻尼器是一种取得专利的新型减震阻尼器，具有“常温高速超塑性”特性；无粘结钢支撑体系是一种机敏的滞回屈服耗能减震支撑体系，可防止支撑在压力作用下屈曲，具有稳定的拉压滞回性能；跷动减震是一种新颖的耗能减震方法，它允许结构上下跷动疏散地震力，减轻建筑损坏。