Wind-induced vibration control of Hefei TV tower with fluid viscous damper

The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation. Firstly, according to the random vibration theory, the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process, and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained. On the basis of the others’ works, a bi-model dynamic model is proposed. Finally, a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers, and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives. Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code. The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper, and the peak acceleration responses of the upper turret is reduced by 43.4%.     

风速谱对大跨度屋盖风振系数的影响

本文基于随机振动理论,在频域内采用风力谱分析法,进行了大跨度梯形钢屋架双坡屋盖随机振动分析。采用6种水平脉动风速谱图,讨论了其对屋盖风振响应和风振系数的影响。同时,讨论了竖向脉动风速谱对所分析大跨屋盖风振响应的影响,以供工程设计及研究工作参考。     

基于大涡模拟的三维高层建筑结构气弹响应数值模拟

以宽高比为1∶6的方形截面高层建筑为研究对象,采用弱耦合分区交错算法,流体域采用大涡模拟方法,进行了紊流边界层风场内三维高层建筑结构多自由度模型的气弹数值模拟,计算中考虑了来流紊流,以及结构的顺、横风向响应。将结构静止时大涡模拟结果与刚性模型测压风洞试验进行比较,验证了该方法在准确预测结构风荷载方面的可行性。通过与气弹模型风洞试验结果的比较表明,本文数值分析方法可用于求解风与结构的相互作用,且具有较高的精度。进行了高折减风速下的气弹数值模拟,研究了结构顶部顺、横风向位移响应随折减风速的变化规律。结果表明：结构风振气弹响应主要为来流紊流引起的顺风向抖振和旋涡脱落引起的横风向涡激振动;折减风速较小时,结构顺、横风向位移振幅相当,且位移响应均相对较小;随着折减风速的增加,结构位移响应增大,横风向涡激振动逐渐占据主导地位,并经历了从“拍”到“涡激共振”的转化。     

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation. Firstly, according to the random vibration theory, the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process, and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained. On the basis of the others’ works, a bimodel dynamic model is proposed. Finally, a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers, and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives. Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code. The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper, and the peak acceleration responses of the upper turret is reduced by 43.4%. __________ Translated from Journal of Southeast University (Natural Science Edition), 2008, 37(6): 1018–1022 [译自: 东南大学学报(自然科学版)]     

大跨度梯形钢屋架双坡屋盖风振响应和风振系数研究

基于随机振动理论,在频域内采用风力谱分析法进行大跨度梯形钢屋架双坡屋盖随机振动分析,用Davenport风速谱计算屋盖的风振响应和风振系数.讨论基本风压、屋盖跨度、屋盖重量、阻尼比、地貌类别和支座约束等参数对风振系数的影响,利用参数分析的结果,归纳出大跨度梯形钢屋架双坡屋盖风振系数实用公式.     

三管集束式钢烟囱风致响应与风振系数研究

为研究三管集束式钢烟囱风致响应与风振系数,以国内某在建180m高三管集束式钢烟囱为研究对象,通过同步刚体测压风洞试验,得到了不同风向角下三管集束式钢烟囱各排烟筒表面平均与脉动风压;采用有限单元法建立排烟筒-加劲环-工字梁一体化有限元模型,对不同风向角下三管集束式钢烟囱结构体系的风致响应进行完全瞬态时域动力分析,研究以径向位移、子午向轴力、环向弯矩和von Mises应力等4种响应作为响应目标的排烟筒一维、二维和三维响应风振系数分布特性及取值标准,给出了典型风向角下三管集束式钢烟囱分层及整体风振系数的取值建议。研究表明：基于4种响应目标的风振系数沿子午向和环向具有明显的二维分布特征,层风振系数随高度逐渐增大,整体风振系数建议取值为2.12。     

多风向多目标等效静风荷载分析方法及应用

针对大跨空间结构中多振型参与风振响应特点和工程应用需要,提出针对多个风向的多目标等效静风荷载分析方法。根据所有风向的平均风荷载（或者风振响应极值）分布之间的相似性指标,将所有风向分为若干个风向区,计算各风向区的风振包络响应;在每个风向区内,选择平均风荷载分布和结构主导振型惯性力作为构造多目标等效静风荷载的基本向量,根据最小二乘法,得到基本向量的最优组合系数,从而得到针对多个风向、多个等效目标的等效静风荷载。将该方法用于某大型科技新馆,分析结果表明：根据各风向下屋面平均风压系数分布间的相关系数,36个风向角仅需分成3个风向区,且各风向区等效静风荷载作用下的静力响应与实际动力响应包络响应吻合较好,验证了所提方法的计算精度和工程应用的便利性。     

基于一致耦合法某大型博物馆结构风致响应精细化研究

针对传统三分量方法中采用SRSS组合背景分量和共振分量获得脉动风总响应的局限,在结构动力学和随机振动理论基础上,推导出结构脉动风总响应的实际理论组合计算式,提出用于补偿背景分量和共振分量之间耦合项的一致耦合法来求解结构的风致响应。该方法从理论上适用于任一复杂柔性结构的风致响应精细化分析。以某大型自然博物馆柔性钢结构为例,采用一致耦合法以及改进的三分量方法进行风致响应计算,并与全模态完全二次型（CQC）法计算结果进行对比分析,结果表明：背景、共振及其交叉项分量均需考虑,其中又以共振分量为主导,并且共振模态之间的耦合效应显著,背景和共振分量之间的交叉项也不能忽略。一致耦合法具有较高的精度和稳定性,是此类结构风振响应机理分析的有效方法。     

基于风洞试验的超高层建筑结构风振时程分析

目前超高层建筑结构风振分析常采用的是规范的简化理论方法和基于风洞试验方法频域方法．随着结构体型的复杂化或周边建筑对风场有明显干扰时，进行结构风振时程分析是更为简单直接有效的方法。本文通过编程实现生成风洞试验中风荷载时程数据并导入有限元分析软件进行结构的时程分析，获得整体结构位移、内力以及加速度时程等重要数据，为规范方法不适用的超高层建筑结构风振响应分析及舒适度评估提供了可行的方法。     

基于响应时程的大跨度空间结构等效静风荷载分析方法

提出以特定时刻的瞬时风压分布为基础,计算大跨度空间结构等效静风荷载的基本方法。首先利用广义坐标合成法得到目标响应的时程,从中确定产生最大响应的时刻,再以该时刻的瞬时风压分布为基础,采用动力放大因子法或附加风振力法计算等效静风荷载。当采用附加风振力法将瞬时风压和附加风振力叠加时,可以得到与风压作用方向不同的等效静风荷载,避免了在某些情况下对风压的过度放大。为便于工程应用,根据精确的等效静风荷载计算式,将荷载中的准静态分量和附加风振力分离,提出了附加风振力的简化计算式。通过大型结构算例分析,证明采用上述方法可以给出合理的等效静风荷载分布,不但能够保证响应目标的等效,其他响应也符合真实情况。     

薄壁空心高墩施工阶段顺风向风振响应分析

根据随机振动理论,分别利用频域法中的风振系数法和桥梁静阵风法计算了薄壁空心高墩施工阶段顺风向风振响应,通过对比分析两种计算结果,表明两种计算方法都适用于薄壁高墩施工阶段顺风向风振响应分析,误差很小,也为同类型结构计算提供了参考价值。     

Wind-Induced vibration responses of prestressed double-layered spherical latticed shells

This paper focuses on the wind-induced vibration response of prestressed double-layered spherical latticed shell (PDSLS) structures by adopting time-domain analysis method. Welch spectrum analysis method is used to make precision evaluation of power spectrum of fluctuating wind speed time history simulated by weighted amplitude wavelet superposition (WAWS) method and linear filtering method of auto-regression (AR) model. Results show that the two methods produce little precision difference, but AR method is far more efficient than WAWS and is more suitable for wind speed simulation of PDSLSs. The effect of various parameters on the wind-induced vibration response of PDSLS structures are comprehensively investigated, including rise-span ratio, span, shell thickness, elastic constraint stiffness, prestress value, with or without cables and cable layout scheme. Results show that rise-span ratio and span are the major factors that affect wind-induced vibration response of PDSLSs. When cables are set, the wind vibration coefficient of nodal vertical displacement becomes smaller and more equally distributed, which demonstrates that PDSLSs are less sensitive to fluctuating wind effect than common latticed shell structures without cables. Finally, based on the envelopment concept and with the maximum dynamic and average wind-induced displacement responses as control indicators, the calculating method for global wind vibration coefficient (GWVC) of PDSLSs is proposed and the value with usual design parameters is given. Meanwhile, when the structure is made static analysis by means of the equivalent static wind load obtained from GWVC, the obtained internal member force response is relatively accordant with the actual response got from time-history analysis, and is a little safer.     

高层建筑玻璃幕墙线性和非线性抗风动力可靠性分析(1)

研究了风荷载的统计方法;然后用板理论建立了幕墙的线性和非线性风振响应分析模型;继而用振型分解法建立了线性风振响应的计算公式,用伽辽金法和改进的等效线性化法求解了荷载为非零均值的非线性风振响应方程;最后依据定义,用泊松过程法建立了线性动力可靠性的计算公式,针对非线性最大动应力是一非高斯随机过程情况,用泊松法和非线性变换,建立了非线性动力可靠性的计算公式,并给出算例;从而给出了幕墙线性和非线性抗风动力可靠性分析的一整套方法。     

基于风洞试验的苏通大跨越输电塔风振系数研究

苏通大跨越输电塔的结构形式有别于普通的钢结构杆塔,其塔身下部结构采用钢管混凝土、上部结构采用钢管,质量突变大,主要受风荷载控制,并且塔高超出GB 50009—2012《建筑结构荷载规范》的梯度风高度限制。为此,采用气动弹性模型和刚性模型的边界层风洞试验确定苏通大跨越输电塔的风致响应和气动力,基于试验数据计算不同风向角下的惯性力风振系数、位移风振系数和有效荷载风振系数,并进行对比。并通过有限元分析梯度风高度对惯性力风振系数的影响,同时将有限元分析得到的风振系数分布和加权值与DL/T 5154的风振系数规定作比较。结果表明：上述3种风振系数分布规律并不相同,由其分别确定的等效位移接近于试验值;考虑梯度风高度后,风振系数变小,分布形状影响小;苏通大跨越输电塔的惯性力风振系数加权值小于1.6,且风振系数由下到上不是单调增大。     

大跨双层屋盖结构风洞试验与风振响应研究

对南太湖湿地奥体公园复杂体型体育场双层屋盖结构进行了风荷载的风洞试验与风致动力响应研究。屋盖由高低两个开口椭圆屋面叠合而成,两屋面之间设置观光走廊。利用风洞模型试验测定了双层屋盖上下表面的平均和脉动风压时程数据。通过计算分析得到了屋盖结构局部测点的极值风压以及平均风荷载整体合力与最不利风向角。然后基于有限元方法对该屋盖进行了风振响应的动力时程分析,获得了结构风振系数、等效静力风荷载的分布图以及考虑风振效应的最不利风向等数据和结论。     

高振型对合肥电视塔风振响应的影响分析

首先根据随机振动理论 ,按照M .Shinozuka方法仿真得到了作用在合肥电视塔上的1 9维互相关的人造脉动风压时程样本曲线。然后基于振型叠加法 ,计算了合肥电视塔在脉动风荷载作用下各个振型上的时程反应 ,分析了高振型对合肥电视塔风振响应的影响程度     

Time-frequency analysis of typhoon effects on a 79-storey tall building

Di Wang Tower located in Shenzhen, PR China, has a height of approximately 325 m and is a 79-storey tall building. This paper presents selected results of full-scale measurements of typhoon effects on Di Wang Tower. Wind speed, wind direction, wind-induced acceleration and displacement responses were simultaneously and continuously measured from the super tall building with anemometers, accelerometers and global position system (GPS) during a typhoon. The advanced data analysis method called Hilbert-Huang transform (HHT) was adopted in this study to analyze the non-stationary characteristics of wind speed and wind-induced responses of this building under typhoon condition. By using the empirical mode decomposition (EMD) method, the measured data were decomposed into several inherent intrinsic mode functions (IMFs). The probability density and power spectral density of fluctuating wind speed were obtained by traditional methods and were further analyzed by considering time-varying mean values of the measured data via the EMD method. The wind-induced responses with non-stationary features were studied by applying the HHT to each IMF for obtaining their instantaneous frequency and Hilbert-Huang composite spectrum. Meanwhile, the transient energy distributions of the wind-induced responses were analyzed in time-frequency domain, which were compared with the traditional power spectral densities obtained from the fast Fourier transform (FFT) method and those from the wavelet transform. Furthermore, the amplitude-dependent damping ratios were determined by combining the EMD and the random decrement technique (RDT) method. Through comprehensive analysis of the measured data, it was testified that the HHT method is a promising tool for the time-frequency analysis of random signal and can serve as a flexible and effective tool for analyzing field data of wind speed and wind-induced response with non-stationary features.     

基于数值模拟法的张力膜结构风振响应分析

针对张力膜结构这种柔性结构非线性程度高、质量轻、刚度弱、风敏感等特点,利用非线性随机振动理论,采用数字模拟法在时域对张力膜结构进行了风激动力响应分析．利用线性自回归过滤器,引入适当的三维空间相关性公式,根据脉动风的特性产生时域内的样本函数,然后根据样本函数利用有限元法在时域内求解运动微分方程得到张力膜结构的风激动力响应,最后由响应值求得结构振动的位移、速度、加速度的均值和均方差等统计信息．从中获取张力膜结构的风激动力响应特性,并给出风激动力响应与结构参数的关系,为继续开展张力膜结构的研究工作提供一些有益的参考．     

高矢跨比椭圆抛物面弦支穹顶风振系数研究

常州市体育馆弦支穹顶,采用Levy型索杆体系以及外部联方型和内部凯威特型网格单层网壳。与常规已研究的弦支穹顶相比,其高矢跨比使网壳具有较大刚度,其椭圆抛物面外形使屋盖在水平风载作用下既存在风吸区也存在风压区。结合工程进行了高矢跨比椭圆抛物面弦支穹顶的风振时域分析,研究了网壳和索杆系的风振响应,在风振作用下,拉索索力和支座竖向反力减小,但拉索未松弛,风载未超过恒载;索杆系应力的均值和波动范围较小;网壳的纵轴和横轴上的响应变化规律较为一致,最大竖向位移出现在靠近中心的2~4环;网壳内环的竖向位移风振系数比较均匀,外环波动较大。通过统计风振响应参数,探讨了整体风振系数的计算方法。基于响应均值和最大值的线性关系,采用风振响应与平均风静力响应的最大值之比作为适用于风载静力分析的整体风振系数,并提出不同风向下的建议值。方法简便,无需判定奇点和统计各样本响应时程。风振响应分析结论及整体风振系数计算方法和结果,可为类似结构的抗风     

鞍形索网等效静力风荷载研究

针对大跨度屋盖结构多振型参与振动的特点,提出了一套确定该类结构等效静力风荷载的精细化方法。该方法的流程包括风振响应分析和静力等效两个阶段,每个阶段又分为平均分量、背景分量和共振分量等3个部分分别进行研究。风振响应分析时,背景响应分析采用准静力方法;共振响应分析综合运用本征正交分解法(POD法)和Ritz向量直接叠加法。静力等效时,等效静力风荷载的背景分量采用荷载响应相关系数法分析,其共振分量表示为多个主要参与振型惯性力的组合。基于本文的分析方法,对一鞍形索网结构的风振响应和等效静力风荷载进行了研究,探讨了不同风向下、针对不同响应的等效静力风荷载分布情况。结果表明本文方法能够有效地分析大跨度屋盖结构的风振响应和等效静力风荷载,能够解决大跨度屋盖结构中多振型参与振动这一主要问题。