Contribution of tuned liquid column gas dampers to the performance of offshore wind turbines under wind, wave, and seismic excitations

The main intention of the present study is to reduce wind, wave, and seismic induced vibrations of jacket- type 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.

Suppression of Wave-Excited Vibration of Offshore Platform by Use of Tuned Liquid Dampers

This paper describes experimental and theoretical investigations of Tuned Liquid Damper (TLD) characteristics for suppressing the wave-excited structural vibration. The structural model for the experiments is scaled according to a full size offshore platform by matching their dynamic properties. Rectangular TLDs of different sizes with partially filled liquid are examined. By observing the performance and behavior of TLDs through laboratory experiments, the Study investigates the influence of a number of parameters, including container size, container shape, frequency ratio, and incident wave characteristics. In an analytical study, a mathematical model that describes the nonlinear behavior of liquid in TLD and the interaction of TLD and structure is prerequisite. The validity of the model is evaluated and simulating results can reasonably match the corresponding experimental results.

Control performance comparison between tuned liquid damper and tuned liquid column damper using real-time hybrid simulation

Tuned liquid damper (TLD) and tuned liquid column damper (TLCD) are two types of passive control devices that are widely used in structural control. In this study, a real-time hybrid simulation (RTHS) technique is employed to investigate the diff erence in control performance between TLD and TLCD. A series of RTHSs is presented with the premise of the same liquid length, mass ratio, and structural parameters. Herein, TLD and TLCD are physically experimented, and controlled structures are numerically simulated. Then, parametric studies are performed to further evaluate the diff erent performance between TLD and TLCD. Experimental results demonstrate that TLD is more eff ective than TLCD under diff erent amplitude excitations.

Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation

In this study, the effectiveness of a tuned liquid column-gas damper, TLCGD, on the.suppression of seismic-induced vibrations of steel jacket platforms is evaluated. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. The objective here is to find the optimum geometric parameters, namely orientation and configuration of vertical columns, length ratio, and area ratio of the TLCGD, considering nonlinear damping of the TLCGD and water-structure interaction between the jacket platform and sea water. The effects of different characteristics of ground motion such as PGA and frequency content on the optimum geometry are also investigated and it is observed that these features have some influence on the optimum area ratio. Finally it is observed that pulse arrangement of ground acceleration is one of the most important parameters affecting the efficiency of a TLCGD. In other words, it is found that the TLCGD＇s capability to reduce the RMS responses depends only on the frequency content of the ground acceleration, but its capability to reduce the maximum responses depends on both the frequency content and the pulse arrangement of the ground acceleration.

Seismic Response Reduction for Fixed Offshore Platform by Tuned Liquid Damper

An approach to seismic response reduction for offshore platforms by the use of the tuned liquid damper is presented in this paper. First of all, the effects of the tuned frequency ratio and excited frequency ratio on the seismic response reduction of the platform structure are investigated. Based on the results, a mechanical model and equation of motion for the TLD-platform system are established. And then effectiveness of the appraoch is verified by numerical calculation.

Seismic response control with density-variable tuned liquid dampers

In this paper, the seismic effectiveness of a density-variable tuned liquid damper （DVTLD） with a sloping bottom is experimentally investigated through a series of shake table tests on a 1/4-scale, 3-story frame structure and numerically simulated by a new semi-analytical model. Special attention was given to reducing the first peak and maximum response under near- and far-field ground motions, and the robustness of a density-variable control system consisting of multiple DVTLDs with closely-spaced frequencies. Adaptable to earthquake excitations, the density-variable control system has been demonstrated to be more effective and more robust than its corresponding traditional tuned liquid damper in suppressing story drift and floor acceleration of the structure. Numerical simulations of the DVTLD-controlled structure agreed very well in phase with experimental results but somewhat overestimated the amplitude of the structural response.

Torsionally Coupled Response Control of Offshore Platform Structures Using Circular Tuned Liquid Column Dampers

In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.

Impact of seismic excitation characteristics on the efficiency of tuned liquid column dampers

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.

附加TLD的中石化巴陵己内酰胺搬迁项目80m自立式不锈钢烟囱风振响应分析

自立式钢烟囱作为典型的高耸结构具有柔度大、阻尼小的特性,易在风荷载以及地震等水平力作用下发生共振进而产生破坏。本文以中石化巴陵石化己内酰胺搬迁项目80m自立式不锈钢烟囱为研究对象,使用附加调谐液体阻尼器(tuned liquid damper,TLD)的方式对其在随机脉动风荷载作用下的水平振动进行控制。利用PKPM和Abaqus有限元软件完成建模并对其进行模态分析,发现钢烟囱水平向的振动以一阶模态为主,并获取结构自振频率、振型有效质量和振型系数等参数。根据《建筑结构风振控制技术标准》设计TLD,通过matlab生成随机脉动风后对附加/不附加TLD的钢烟囱进行时程分析,对比位移响应和加速度响应情况并计算减振率。结果显示:附加TLD后,钢烟囱的峰值位移减振率达到35.38%,均方根位移减振率达到22.55%;峰值加速度减振率达到32.61%,均方根位移减振率达到22.37%,表明TLD能高效减小自立式钢烟囱的风振响应。

Wind-induced vibration control of bridges using liquid column damper

The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper.By installing the TLCD in the bridge deck,a mathematical model for the bridge-TLCD system is established.The governing equations of the system are developed by considering all three displacement components of the deck in vertical,lateral,and torsional vibrations,in which the interactions between the bridge deck,the TLCD,the aeroelastic forces,and the aerodynamic forces are fully reflected.Both buffeting and flutter analyses are carried out.The buffeting analysis is performed through random vibration approach,and a critical flutter condition is identified from flutter analysis.A numerical example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective device for suppressing wind-induced vibration of long span bridges,either for reducing the buffeting response or increasing the critical flutter wind velocity of the bridge.

利用TLD减小高柔结构多振型地震反应的研究

本文提出了利多多个调谐液体阻尼器（简称TLDS）减小高柔结构多振型地震反应的方法，给出了TLD的布置方案和计算公式，通过钢框架模拟地震振动台试验和理论分析，验证了本文提出的方法的正确性．

设置竖向隔板的矩形TLD的动力特性

基于线性波浪理论 ,建立了设有竖向隔板的矩形TLD液体晃动问题的基本方程 ,并给出了晃动力的计算公式 .通过数值计算 ,研究了设有竖向隔板的矩形TLD动力特性 。

调频液体阻尼器(TLD)的等效力学模型研究

本文根据流体力学理论，建立了圆柱形ＴＬＤ中晃动液体的势流场，并从液体晃动的动力效应等效原则出发，导出了晃动液体的等效力学模型，并阐明其适用范围。文量计算的结果表明，在工程应用中，仅用ＴＬＤ的一阶晃动等效力学模型就能满足工程需要。

调谐液体阻尼器(TLD)附加阻尼力的量测

设计一种可以直接测量调谐液体阻尼器的附加阻尼力的实验系统。该系统采用半仿真半实物相结合的方法;结构模型的响应计算在计算机中实现,此部分为数值仿真部分。响应结果输入到由计算机控制的液压作动器,而作动器连接到用于模拟海洋平台甲板振动的移动台,移动台台面上放置TLD实物装置,此部分为实物部分。安装于作动器与振动台之间的力传感器可以测量到液体晃动对结构产生的反作用力。测试在简谐激励下TLD的附加阻尼力,并将测试结果与理论计算值进行比较,验证该系统的有效性。

内置横向圆柱体TLD的动力特性分析

为增大调谐液体阻尼器(TLD)中液体的晃动质量,以获得更优的动力特性,首次提出内置横向圆柱体TLD(TLD embedded a transverse cylinder,简称TLDETC)的概念。结合流体力学原理以及能量方法推导了TLDETC的晃动质量、晃动力、晃动阻尼比以及晃动频率的表达式,并通过三种设置方案对TLDETC与普通TLD进行了动力特性的对比分析。推导结果表明,TLDETC有效地增大了液体的晃动质量;而分析结果表明,TLDETC具有比普通TLD更优的动力性能。

TLD对海洋平台地震反应控制的简化计算方法

调频液体阻尼器 (TuneLiquidDamper,简称TLD)对地面结构位移反应与加速度反应的较好控制作用已得到理论与试验的验证。本文在此基础上研究了TLD对海洋平台动力反应控制的简化计算方法。计算中 ,TLD中液体的控制力采用较精确的数值计算法和简化计算法两种方法 ,通过对海洋平台地震反应计算的结果表明 ,该简化计算方法具有很高的精度 。

TLD控制的钢结构振动台模型试验研究

本文通过钢结构的振动台模型试验,研究了在刚性地基条件下矩形调谐流体阻尼器(TLD)对结构地震反应的减震机理和减震效果,为进一步研究土-结构相互作用对结构TLD减震控制效率影响的振动台模型试验提供对比数据。试验结果表明,在水箱中设置铁丝网有助于提高TLD的减震效率,地震动的频谱特性和峰值加速度大小对TLD的减震效率有重要影响。

海上平台利用TLD的减震研究

通过减震试验和数值计算来研究液体调频阻尼器(TLD)在地震荷载作用下对渤海CB32A海上平台的减震作用。减震试验主要研究缩尺后TLD对平台模型在EL Centro波、天津波及规范谱拟合人工波作用下所产生的振动反应的影响。数值计算主要研究原型结构受上述地震波的激励作用的TLD减震效果。结合试验和理论分析结果,给出了海洋平台结构的TLD减震控制的一般设计方法,以供设计人员参考。

圆柱形二层流体TLD的振动特性分析

利用水波理论推导并求解出圆柱形二层流体TLD的振动基本方程，并对其自振特性和周期性强迫振动响应进行了分析，分析表明二层流体TLD的频率特性不同于单层流体TLD，进一步指出圆柱形二层流体TLD作为减振控制装置具有的潜在优势。

高层钢结构地震反应控制的MTLD系统优化设计

本文对高层钢结构ＭＴＬＤ地震反应控制优化设计方法进行了初步的探讨。建立了结 构－ＭＴＬＤ系统的动力方程。根据导出的结构－ＭＴＬＤ系统动力放大系数计算公式，通过数值分 析，研究了ＭＴＬＤ系统各设计参数之间的关系，给出了ＭＴＬＤ系统最优设计参数。给出了 ＭＴＬＤ系统优化设计步骤和结构－ＭＴＬＤ抗震设计具体方法。最后给出了３０层钢结构ＭＴＬＤ 地震反应控制仿真分析。