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.

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.

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.

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.

调谐液柱阻尼器-结构系统风致振动响应的CFD/CSD耦合分析方法

针对调谐液柱阻尼器(tuned liquid column damper, TLCD)难以建立其精确的非线性理论分析模型,且其力学性能试验成本高和耗时长等问题,首先采用计算流体动力学(CFD)数值模拟方法,对TLCD系统的力学性能和动力特征进行仿真模拟,在此基础上进一步提出了基于计算流体动力学/计算结构动力学(CFD/CSD)耦合分析方法,求解带TLCD系统的高层建筑结构的风致动力响应。通过开展某一TLCD系统在特定底部激励下的力学性能和动力特性试验,得到其内液体晃荡的自由液面波高和晃动力时程,验证了CFD数值模拟方法可以准确地分析TLCD水箱内液体的非线性晃动特征。随后对风工程领域广泛采用的76层建筑结构振动控制Benchmark模型,假设其顶部设置TLCD系统时主体结构在三种风速重现期(10、50和100年)风速对应的横风向动力风荷载激励下的风致控制效率,采用提出的CFD/CSD耦合分析方法,进行了数值仿真模拟分析。耦合分析结果表明,TLCD系统对Benchmark模型的风致加速度、速度和位移响应均有一定的控制效果,对加速度响应的控制效果要优于对位移响应的控制效果。该研究方法可为复杂TLCD系统对高层建筑的风振控制分析提供有效的参考。

多维地震作用下非对称结构利用TLCD减震控制研究

本文提出在结构两正交方向同时设置Ｕ形调液阻尼器（ＴＬＣＤ）用来减小地震作用下的平动－扭转反应。文中建立了结构－ＴＬＣＤ体系在多维地震动作用下的运动方程，分析了系统参数对减震效果的影响，最后通过数值算例，给出了高层建筑平扭耦联地震反应的减震效果。

建筑结构利用TLCD减振的神经网络智能控制

本文提出了建筑结构利用调谐液体柱型阻尼器（ＴＬＣＤ）减振的神经网络智能控制方法．首先阐 述了确定ＴＬＨＤ半主动控制策略；然后利用ＢＰ人工神经网络方法计算并控制ＴＬＣＤ隔板孔洞的面 积，以调节和控制阻尼比，实现对建筑结构的智能控制．地震作用下的数值分析表明，本文所述 的方法是十分有效的。

半主动变刚度TLCD减振控制的研究

为改进被动式调频TLCD的减振特性,提出了半主动变刚度TLCD减振系统,基本原理是将调频TLCD的弹簧设置成可调谐状态,在振动过程中,根据减振系统的需要适时调整调频弹簧的开关状态。由Lagrange方程建立起半主动变刚度TLCD的运动方程,以一个单自由度结构体系为算例,分析了可变刚度对系统控制性能的影响。研究了半主动变刚度TLCD的减振性能。通过一个五层结构的算例,分别在谐波和地震波作用下,验证了半主动变刚度TLCD对多自由度结构体系的减振特性。结果表明,半主动变刚度TLCD具有更宽的减振频带,在TLCD的频率和结构振动的频率存在误差时,仍能保持较好的减振效果。

含TLCD超高层建筑风振舒适度及其生命周期费用分析

超高层建筑高、柔,风振影响显著,工程中常需配置调频液柱阻尼器(TLCD)以减小振动、提高人居舒适度。针对在强风作用下TLCD可能存在液体运动撞击容器顶部或液面低于水平段等失效问题,进行了TLCD的抗风可靠度研究,并对超高层建筑结构-TLCD体系的生命周期费用进行了分析。采用虚拟激励法计算结构-TLCD体系在脉动风荷载下的随机风振响应;基于随机振动的首次超越破坏准则,研究结构-TLCD体系在不同风速风载下的动力可靠度;分析结构-TLCD体系的风振舒适度生命周期费用;依据生命周期费用最小原则进行投资决策,是基于性能的抗风设计的具体应用。利用该方法对某超高层建筑结构的TLCD安装与否进行了投资决策,说明了本方法的适用性。

波浪荷载作用下导管架海洋平台利用TLCD的振动控制

海洋平台是海洋能源开发的基础设施,除了安全性、稳定性要求之外,其舒适性也是倍受关注的问题之一。调液柱型阻尼器(tuned liquid column damper简称TLCD)通过液体在柱内的晃动从而消耗输入到平台结构的能量,以达到减小平台结构响应的目的。文中对安装有调(TLCD)的导管架海洋平台进行了振动控制分析。假设波浪荷载模型分别为高斯平稳白噪声过程和波浪谱模型,利用随机振动理论对不同的波浪荷载模型分别进行TLCD的参数优化,从而比较平台结构位移响应的减振率。为了更好地反映实际波浪特点,在采用波面谱的同时引入波浪的方向谱,比较计入波浪方向分布对结构响应控制的影响。

基于市场机制的TLCD半主动控制方案

基于市场机制控制是利用市场来模拟复杂的控制系统,用销售商和消费者来代替控制器和受控结构,从而将整个控制系统离散化,对结构的振动实施有效的控制。本文将基于市场机制的控制理论应用于TLCD半主动控制,提出了一种新的TLCD的半主动控制方案,即基于市场机制的TL CD半主动控制方案。首先建立TLCD-结构控制体系的运动方程,给出了半主动控制方案,用一个单自由度结构为例来阐述基于市场机制的TLCD半主动控制方案并对控制系统进行分析。然后用一个五层结构来验证这种方法的有效性。结果表明,基于市场机制的半主动TLCD开关控制不仅减振效果好,而且节约能量,简单易行,便于在实际工程中应用。

采用神经网络半主动TLCD对海洋固定式平台的振动控制

本项工作为研究半主动调液柱型阻尼器(TLCD)对固定或海洋平台的减振控制方法。首先建立TLCD-平台结构系统在地震和波浪作用下的运动方程,给出了半主动控制策略,即不断地调整TLCD的开孔率,使其能对平台结构达到最优的减振效果。由于TLCD中液体运动具有较强的非线性,用神经网络实时调节TLCD的开孔率,并通过数值算例验证了该方法的有效性。

半主动TLCD对固定式海洋平台的离散神经网络滑模控制

主要研究了半主动调液柱型阻尼器(TLCD)对固定式海洋平台的离散神经网络滑模变结构控制方法。首先建立了平台结构-TLCD控制系统微分方程及其离散化状态空间表达,然后阐述了基于神经网络的滑模变结构控制的基本算法和控制策略,最后应用该神经网络滑模变结构控制策略对一个已建成的实际海洋平台结构的TLCD半主动控制问题进行了数值仿真分析。仿真分析的结果证明了该方法的有效性。

磁流变环形调液阻尼器(MR-CTLCD)对结构扭转振动控制的参数研究

研究在地震激励下,磁流变环形调液阻尼器对结构扭转反应的控制.首先建立磁流变环形调液阻尼器在地震作用下的运动方程,根据随机振动虚拟激励法一般原理,推导地震作用下磁流变环形调液阻尼器振动控制最优控制参数的表达式,对结构纯扭转的振动问题进行研究,分析各参数对最优等效阻尼比和最优频率比的影响,以及各参数对磁流变环形调液阻尼器减振效果的影响.结果表明,磁流变环形调液阻尼器能有效较小结构扭转振动,是一种有效的结构扭转振动控制装置.

MTLCDI控制连体超高层建筑风振响应研究

将惯容元件与安装在连体超高层建筑各自原有的水箱串联组成多调谐液柱惯容阻尼器(MTLCDI),用于控制连体超高层建筑的风振响应。MTLCDI不仅发挥水箱供水和消防的功能,还利用惯容元件的质量放大效应使其在实际质量较小的情况下有效控制主体结构的风致响应。建立了MTLCDI控制连体超高层建筑风振响应的非线性运动方程,用等效线性化方法讨论该方程的解;结合测压风洞试验,以某一连体超高层建筑为工程实例分析MTLCDI的振动控制效果;将MTLCDI控制效果与单、多调谐质量惯容阻尼器(TMDI,MTMDI)、单调谐液柱惯容阻尼器(TLCDI)的控制效果进行比较。结果表明:与其他3种阻尼器相比,MTLCDI能有效减小连体超高层建筑的风致加速度响应、脉动位移响应和层间位移角,还兼具有效利用建筑物各自水箱和节省安装空间的优势。研究结果为连体超高层建筑风振控制设计提供参考。

TTLCD-偏心结构转化为TTMD-偏心结构的减振控制研究

针对偏心结构,研究在地震激励下,扭转调频液柱阻尼器(TTLCD)系统优化参数和对结构减振控制的模拟。首先通过比较TTLCD-结构体系和TTMD-结构体系的耦联微分方程,可将TTLCD-结构体系转化为TTMD-结构体系,从而得到TTLCD-主结构与TTMD-主结构质量比、频率比、主结构自振频率和主结构阻尼等,利用Ikeda公式对TTLCD阻尼比和频率比参数优化,并用有限元软件来对复杂结构减振控制进行数值计算。通过单层偏心结构和4层偏心放置单个或多个TTLCDs为例,用Ikeda公式求得TTLCDs参数,并用SAP2000进行结构分析,同时与MATLAB结果进行对比,验证了该方法的合理性和可行性。

Semi-Active TLCD Control of Fixed Offshore Platforms Using Artifical Neural Networks

In this paper, the control method for fixed offshore platforms using semi-active tuned liquid column damper (TLCD) is presented. The equation of motion for the platform-TLCD control system is given and the semi-active control strategy is established. A back propagation artificial neural network (ANN) is used to adjust the orifice opening of TLCD because of the nonlinear motion of liquid in TLCD. The effectiveness of the control method is verified by numerical examples.

TLCD-基础隔震框架结构的减振控制研究

为了避免和减轻由过大隔震层位移引起的损害,对基础隔震框架结构装设调频液柱阻尼器(tuned liquid column damper,简称TLCD)后混合系统的减振效果进行研究。建立了单层和多层混合控制系统在地震作用下的运动方程,采用TLCD-结构体系转化为调频质量阻尼器(tuned mass damper,简称TMD)-结构体系的等效方法,利用TMD参数优化公式,得到单个TLCD初始设计参数,并采用状态空间方程得到多个TLCD最优设计参数。通过对某8层基础隔震结构进行模拟,证明了该理论设计方法的合理性。该混合结构不仅可以减小隔震层位移和加速度,而且对上部结构位移和加速度反应都能更有效的控制。