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  • 學位論文

半圓頂型屋蓋結構物表面擾動風壓之特性探討

Characteristics of Wind Pressure Fluctuations On Dome-Like Structures

指導教授 : 羅元隆

摘要


當體育表演與娛樂活動的興起、大量儲存空間的需求出現,能夠解決此問題的大型結構就是大跨度建築,大跨度的想法應用於橋樑結構、建築屋頂結構等,其建築擁有能以最小表面積卻能產生出最大封閉室內空間,過去建築師使用磚石建造拱頂建築,跨度多達40多公尺,如羅馬的聖彼得大教堂,為了要求能夠容納更多人進行集會活動的空間,透過提升建築材料的強度,現今許多的大跨度建築其跨度都超過200公尺以上,如日本東京巨蛋、中國北京鳥巢體育館、台北小巨蛋等。 由於跨度大且材質輕的特性,屋蓋表面受風壓分布影響甚鉅,一般不建議以簡易計算方式給定設計風載重,而另行於規範中表列外風壓係數值進行設計。過去大跨徑屋蓋結構相關文獻中,對於表面風壓特性的討論不勝少數,但大部分為定性探討。本研究進行以不同屋蓋曲率及不同雷諾數為兩項控制參數,探討交相關頻譜特性的表面分布特性,並藉由半經驗公式針對兩鄰近擾動風壓之Root-coherence函數進行擬合。以擬合之結果討論其沿著表面上下游的趨勢變化,作為計算風力載重之依據。 由擬合結果得知,依據屋蓋曲率f/D的不同,可以明顯地觀察到交相關頻譜的變化甚鉅;當相鄰兩風壓的間隔增大時則更能凸顯變化。而底座側牆的變化h/D則對交相關頻譜幾乎沒有影響。而從不同雷諾數結果來看,其變化不如屋蓋曲率f/D來得明顯。由本研究的擬合結果中,某些位置的擬合還不夠準確,例如分離點發生位置前後,流場特性改變劇烈導致一般經驗公式尚不足以模擬之。

並列摘要


When the rise of sports performance and recreational activities, many requirements of storage space.we find that the Dome-like structures can able to solve this problem . The idea of Dome-like structures used in long-span bridge structure, building roof structure. Its building has a surface area with minimal able to produce the largest closed interior space.In the past time, the architects built Dome-like structures in bricks.The span could up to 40 km. Such as St. Peter's Basilica in Rome.Now,we can get more requirements space to accommodate people activities by improve strength building materials. It’s span can up to 200km. Such as Japan Tokyo Dome, China’s Bird's Nest Stadium in Beijing, , Taipei Arena and so on. Due to large span and light material properties,the distribution of the roof surface by wind pressure is very huge. Generally not recommended with a simple calculations for a given design wind load. Over the relevant literature discusses of the characteristics of the surface pressure in Dome-like structures are victorious minority. However,most of the discussion are qualitative. In this research with many different roof curvature and reynolds number for two different control parameters. Discussion on surface of the spectral characteristics. Then,we can fit coefficient C and K of the two neighboring wind pressure spectral according to the empirical formula of the Root-coherence function . Discuss the results of the fitting coefficient during from the downstream along to the trend,As the basis for calculating the wind load. By the fitting results, based on the roof different of curvature f/D , we can clearly observe the changes of the cross-spectral.However,the high h/D doesn’t influence on the fitting results. From the different of Reynolds number , the results are the same as the results of f/D=0.5. Based on these results, fitting certain location is not accurate enough.We need to improve the methods of the fitting Formula.

參考文獻


[2] Cheng,C.M. and Fu,C.L, Characteristics of Wind Loads on a Hemispherical Dome in Smooth Flow and Turbulent Boundary Layer Flow
[3] Hui,M.C.H,Larsen,A. and Xiang,Xiang,H.F. Wind turbulence characteristics study at the Stonecutters Bridge site : Part Ⅱ:Wind power spectra, integral length scales and coherences
[6] N. Toy, W.D. Moss, E. Savory, 1983. Wind tunnel studies on a dome in turbulent boundary layers, J. Wind Eng. Ind. Aerodyn. 1, 201-212.
[7] T.J. Taylor. Wind pressures on a hemispherical dome, J. Wind Eng. Ind. Aerodyn. 40, 199-213.
[8] T.Ogawa, M. Nakayama, S. Murayama, Y. Sasaki . 1991. Characteristics of wind pressures on basic structures with curved surfaces and their response in turbulent flow, J. Wind Eng. Ind. Aerodyn. 38, 427-438..

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