【作者】 王哲；

【导师】 刘慕广； 罗红艳；

【作者基本信息】 华南理工大学 ， 土木水利硕士（土木工程）（专业学位）， 2024， 硕士

【摘要】 台风是一种强烈的气旋性风暴,其外围大风区域范围最大,对工程结构的影响也最为严重,每年都会对我国东南沿海地区造成巨大经济损失。高耸桅杆结构本身的高柔、低阻尼特性导致其风振响应机理复杂,非线性特征显著。本文基于356m高的深圳气象梯度塔风速和加速度实测数据,围绕深圳地区台风外围风场特性、桅杆结构风致响应特征以及模态识别展开研究,主要开展了以下几个方面的工作:(1)统计分析了2019年～2022年间实测获取的7组台风外围风场特性。对于平均风速剖面,指数律的整体拟合效果较好,而对数律模型在10m高和40m高度的拟合效果均最佳;各高度和风向的脉动风速样本峰度系数大多超过3.5,呈现明显的非高斯特征;各方向湍流强度、水平方向阵风因子均与平均风速和高度呈负相关关系;湍流积分尺度与平均风速无明显相关性;四参数风谱模型可以对实测台风外围强风风场脉动风谱实现较好的拟合效果,据此提出了针对深圳地区台风外围强风顺风向、横风向和竖向脉动风谱的建议公式。(2)对比分析了现阶段较为成熟的模态分解和模态识别理论对高耸桅杆密集模态的分解效果以及对塔身模态的识别效果。结果表明:对于塔线耦合密集模态可以通过解析模态分解和随机子空间方法结合稳定图理论处理;考虑到各种模态方法的适用情景,提出了一套针对拉线桅杆结构在工程中不同应用场景的模态参数识别方法建议。(3)分析了台风“圆规”作用下桅杆的风效应。研究发现:强风作用下梯度塔的响应由横风向振动控制;桅杆结构风致加速度响应中多模态参与特征显著,且纤绳的振动不可忽略;塔身模态频率、阻尼比与结构振幅表现出一定相关性。(4)对梯度塔734组1h实测加速度样本的分析发现,桅杆塔身最大加速度响应多发生在塔顶,但也可能发生在300m、250m、160m高度处,加速度响应沿高度的分布曲线可以划分为5种类型;1h加速度响应均方根均符合极值III型(Weibull)分布。对6组典型样本的进一步分析表明:塔身风振强烈时的加速度响应瞬时值概率密度分布基本符合Gauss分布,塔身的前3阶模态能量占比显著,而振动强度相对较低时,响应瞬时值分布则呈现非高斯特征,且风振中的高阶模态能量占主导。更多还原

【Abstract】 Typhoon is a kind of strong cyclonic storm with the largest peripheral gale region and the most serious impact on engineering structures,which causes great economic losses to the southeast coastal area of China every year.The high flexibility and low damping characteristics of the towering mast structure itself lead to its complex wind vibration response mechanism and significant nonlinear characteristics.Based on the measured wind speed and acceleration data of the 356m high Shenzhen meteorological gradient tower,this paper focuses on the characteristics of the peripheral wind field of a typhoon in the Shenzhen area,the wind response characteristics of the mast structure,and the modal identification to carry out the research,and mainly carries out the following aspects of work:(1)Through the analysis of seven sets of typhoon peripheral wind fields measured between 2019 and 2022,we summarize the characteristics of the typhoon peripheral wind fields in Shenzhen:for the mean wind speed profiles,the exponential law has a better overall fitting effect,and the logarithmic law model has the best fitting effect for both the 10m height and the 40m height;the kurtosis coefficients of pulsatile wind samples in all heights and directions are mostly more than 3.5,which present obvious non Gauss characteristics;the turbulence intensity in all directions and the horizontal gust factor are negatively correlated with the mean wind speed and height;the turbulence integration scale is not significantly correlated with the mean wind speed;The four parameter wind spectrum model can achieve a good fitting effect on the measured pulsating wind spectrum of the strong wind field around the periphery of typhoons.Based on this,a suggested formula for the downwind,crosswind,and vertical pulsating wind spectra of typhoon periphery in Shenzhen area is proposed.(2)Comparison and analysis of the decomposition effect of the more mature modal decomposition and modal identification theories on the tower line coupled dense modes of the gradient tower and the identification effect on the tower modes,the results show that:for the tower line coupled dense modes can be dealt with by the analytical modal decomposition and stochastic subspace method combined with the theory of the stability diagram;taking into account of the applicable scenarios of the modal methods,a set of modal decomposition and modal identification methods for different application scenarios of the tensioned line mast structure in the engineering are put forward.Considering the applicable scenarios of various modal methods,a set of modal parameter identification methods are proposed for different application scenarios of tie-line mast structures in engineering.(3)The wind effects of the mast under the wind field in the typhoon fringe area of a typical typhoon event("Round Gauge"in 2021)are analyzed,and it is found that:the response of the gradient tower is controlled by the transverse wind vibration under strong winds;the wind-induced acceleration response of the mast structure is characterized by significant multimodal participation,and the vibration of the fibrous rope can not be ignored;the modal frequency and the damping ratio are related to the structural amplitude of the tower;and the modal parameters are related to the wind-induced acceleration response of the mast structure.,damping ratio and structural amplitude show some correlation.(4)The time-domain characteristics of the wind-induced response of the gradient tower are analyzed by 734 sets of 1h measured acceleration samples in October 2021,and it is concluded that:the distribution curves of the root-mean-square(RMS)of the acceleration response of the gradient tower along the heights can be classified into five types,and the maximum response occurs at the top of the tower,but it may also occur at the heights of 300m,250m,and 160m;the RMS values of the 1h acceleration response of the heights are consistent with the extreme value I and II,and the RMS values are consistent with the extreme value I and II.The root mean square values of the 1h acceleration response at each height are in accordance with the extreme value type III(Weibull)distribution.Subsequently,six groups of typical samples representing towers with different vibration intensities are selected for further analysis,and the following conclusions are obtained:the probability density distribution of the instantaneous values of the tower acceleration response during the strong vibration triggered by the strong wind event basically conforms to the Gauss distribution,while the distribution of the instantaneous values of the response is non-Gaussian when the vibration intensity of the structure is relatively low;the higher-order modal energies are dominant at the lower vibration intensities of the structure and the higher-order mode energies dominate the response of the tower during the increase in the response.In the process of increasing the response,the proportion of the first 3 orders of modal energy of the tower body increases gradually.更多还原