【作者】 杨雄；

【导师】 吴玖荣；

【作者基本信息】 广州大学 ， 结构工程， 2011， 硕士

【摘要】 随着科学技术及施工技术发展,城市开始涌现出一批超高层建筑,如广州西塔(432 m),台北101大楼(508 m),上海中心大厦(632 m)等。本文主要以前2栋超高层建筑为工程背景,根据广州西塔高层建筑台风风场特性和风致结构振动实测数据及台北101风致结构振动和地震振动的实测数据,对其广州西塔的风场特性、结构风致振动和台北101大楼模态参数识别进行一些分析和研究,主要内容包括以下几个方面:(1)以台北101大楼为工程背景,根据结构振动现场实测数据,其中包括多次台风和地震作用下的实测数据,用随机子空间识别法(SSI)和加强频域分解法(EFDD)对台北101大楼在不同荷载工况进行了模态参数识别,识别出台北101大楼在不同荷载工况下的前6阶自振频率、振型、结构阻尼比,分析了SSI三种不同投影矩阵加权算法(SSI-UPC、SSI-PC和SSI-CVA)异同点。结果表明:SSI三种算法结果很接近,PC算法识别精度最高。讨论了应用SSI识别方法时,投影通道技术、稳定图最大状态空间维数,台风强度,荷载类别等因素对模态识别精度的影响。在应用EFDD识别方法进行模态识别时,分析了频率分辨率对识别精度的影响。结果表明:上述的因素对模态识别精度有较大影响。(2)以广州西塔为例,在台风“鲇鱼”的影响下,对其结构振动进行现场同步监测,获得了其风场特性、结构动力特性以及风致结构振动响应等相关结果。结果验证了湍流强度随平均风速增大而减小、阵风因子随湍流强度增大而增大等规律,且实测的顺风向与横风向脉动风速谱均符合Von Karman谱。通过台风作用下楼层顶部加速度数据分析,结果表明测试的结构模态参数结果与有限元分析吻合。同时分析了楼顶平均风速和加速度均方根响应之间的关系。对其结构动力特性(频率及阻尼比)进行了辨识,用随机减量方法求得结构在两个主轴方向的第一振型对应的阻尼比与振幅的非线性关系,同时结果表明阻尼比随振幅增大而增大的特性。上述实测分析结果为超高层建筑设计及相关研究提供了参考。(3)仍以广州西塔为例,通过对其三维有限元模型简化成集中质量“糖葫芦”串模型,采用时域法(改进Newmark-β法)对其利用风洞试验提供的风荷载进行了风致动力时程分析,同时用Matlab7.0编制其程序。根据日本和欧美国家对现有大量建筑实测阻尼的统计结果得到的非线性阻尼模型,讨论了不同结构固有阻尼模型(常阻尼和非线性阻尼模型)和气动阻尼模型对其风致动力时程分析的影响。结果表明:不同阻尼模型工况下进行风致动力时程分析得到结果存在差异,但是仍属于可以接受的范围。时程法的结果跟风洞试验结果具有可比性,说明风洞试验和理论分析结果具有很高可靠性。更多还原

【Abstract】 With the development of science and construction technology, several super high-rise buildings emerges in the modern urban city, such as Guangzhou West Tower (432m), Taibei 101 Tower (508m) and Shanghai Center (632 m) etc. In this paper, typhoon characteristics and wind-induced responses of Guangzhou West Tower has been studied based on the field measurement data during typhoon Megi, and modal parameter identification of Taibei 101 Tower has been also studied by the measured wind-induced response data . The main content of this research work are shown as the following:(1) First modal parameters (including natural frequencies , vibration modes and damping ratios) identification of Taibei 101 Tower was conducted by the SSI method and EFFD method. For the SSI method, the effects of different factors on the estimation accuracy of modal parameters, including excitation types、projection channel technique、the maximum state space dimension of stabilization diagram、the intensity of ambient excitation and selection of weighting projection matrix (SSI-UPC, SSI-PC and SSI-CVA), were analyzed and discussed in this study. Meanwhile the effect of selected frequency resolution on the actuary of modal identification was also studied in this study by EFDD method.(2) The wind characteristics and wind-induced response of this tall building were simultaneously measured when Typhoon Megi affected this tall building. Some results for wind characteristics at about 440m height were obtained from the statistical analysis on the measured wind data: 1) The turbulence intensity decrease with the increasing mean wind speed, while gust factor increases with the increased turbulence intensity, 2) The measured power spectral density of fluctuation wind speed in longitudinal and transversal direction could be fitted very well by Von Karman spectrum. The statistical analyses on the measured wind-induced acceleration response atop the building have shown that the measured natural frequencies are very close to the numerical FEM analyzed results. Finally the relationship between the wind-induced acceleration response atop the building and mean wind speed were obtained from the measured data. 3) Based on the measured acceleration data, amplitude-dependent damping ratios of the building were also obtained by the random decrement method. The typhoon-generated wind characteristics and wind-induced structural vibrations were investigated in detail on the basis of the full-scale measurements.(3) A simplified and reduced model was established based on the 3D finite element model of Guangzhou West Tower. By adopting the time history record of aerodynamic wind load acting on the center of mass at each floor, a modified Newmark-βmethod was developed in this study to evaluate the effect of different amplitude-dependent structural damping and aerodynamic damping models on the wind–induced response of this tall building. Comparing results showed that results obtained from amplitude-dependent structural damping models were some different from those obtained from constant damping assumption. Results from time-domain method were also compared with those from wind tunnel tests, and good agreement between them was found in this study.更多还原