Wind data analysis of a slender supertall structure

Pao Yue-kong Library Electronic Theses Database

Wind data analysis of a slender supertall structure

 

Author: Wang, Bo
Title: Wind data analysis of a slender supertall structure
Degree: M.Sc.
Year: 2012
Subject: Tall buildings -- Aerodynamics.
Wind-pressure.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Civil and Structural Engineering
Pages: xii, 98 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2554570
URI: http://theses.lib.polyu.edu.hk/handle/200/6864
Abstract: Wind loading is a kind of typical dynamic loading, and its effects to structures will be determined by the wind characteristics directly. The corresponding wind properties include the mean wind speed and mean wind direction, turbulence intensity, gust factor, turbulence integral scale and fluctuating wind spectra. While, with regard to most of the existent wind resistance codes, the standards about the wind characteristics are instituted according to the research of monsoons or normal wind. Generally, the wind properties of monsoons and typhoons differ remarkably and the strength of typhoons is greater than that of monsoons. Therefore, it is very necessary to study and analyze the typhoons’ properties in order to provide the scientific foundation for structural wind resistance design in the regions affected by typhoons. The Canton Tower, located in Guangzhou, China, is a super-tall landmark building by the absolute height of 600 m. On the basis of the structural health monitoring (SHM) system implemented in the Canton Tower, the wind data during four tropical cyclones (Haima, Nockten, Nanmadol and Nalgae) were measured in 2011. The measured wind data are analyzed in this dissertation to obtain the mean wind speed and mean wind direction, turbulence intensity, gust factor, turbulence integral length, mean wind pressure, fluctuating mean wind pressure, wind speed spectra and wind pressure spectra. The wind properties and wind pressure parameters are compared with the current design code in China and Japan and the recommended experimental values. The measured maximum 3-second wind speed is less than the corresponding maximum 3-second gust wind speed measured by The Hong Kong Observation in the corresponding period, which means that the measured data of wind properties have large spatial variability due to the different observation location. And the variation ranges of the 10-minute wind direction during three typhoons are less than 60°, which is a relative small variation range.
The longitudinal turbulence intensity is generally larger than the value in the lateral direction, and the trends of variation in longitudinal and lateral direction are very similar and present declining tendency with the rise of mean wind speed. The measured mean values are much larger than the recommended longitudinal turbulence intensity of Japanese wind load code. The longitudinal gust factor is less than the recommended value by the load code for the design of building structures of China and presents linear relationship with the longitudinal turbulence intensity during three typhoons. The measured longitudinal turbulence integral length is much more than the lateral values. While, the measured longitudinal turbulence integral length is much less than the recommended value by Japanese load code. The major reason is considering due to the extremely serried tall building around the Canton Tower. The fitting results on profile of turbulence integral length are provided and the deviation comparing with the measured values are less than 11.0%. The measured longitudinal wind spectra are in accordance with the Von Karman spectra and the deviation between measured longitudinal spectra and Von-Karman spectra is less than 3.50%. Also the lateral wind spectra can be describe according to the isotropy theory, and be in accordance with the Von Karman spectra. The measured wind pressure during typhoon Nalgae is mostly larger than the calculated basic wind pressure based on the wind speed. The maximum mean wind pressure coefficient is 1.46 and the extreme wind pressure coefficient is 2.65. In terms of the fluctuating wind pressure coefficient, the maximum value at all the points is 0.55 and the mean fluctuating wind pressure coefficient is 0.39. The measured wind pressure spectra are similar with Von Karman spectra, while the Davenport spectra is less than the measured spectra in the low frequency section and it is larger than the measured values in the frequency more than 0.01 Hz. It is probably affected by the height.

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