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    Title: 纜索風力係數之風洞實驗量測
    Other Titles: Wind-tunnel measurements of aerodynamic force coefficients of cables
    Authors: 陳雍羲;Chen, Yung-hsi
    Contributors: 淡江大學土木工程學系碩士班
    林堉溢;Lin, Yuh-yi
    Keywords: 斜拉索;圓柱斷面;風壓量測;風洞實驗;inclined cables;circular cylinder;wind pressure measurements;wind-tunnel test
    Date: 2009
    Issue Date: 2010-01-11 05:23:32 (UTC+8)
    Abstract: 在本文中,主要是探討斜張橋斜拉索在風向平行於橋軸和垂直於橋軸兩種不同方向傾角的受風效應。將斜拉索視為圓柱斷面進行風洞試驗,從圓柱斷面在不同傾角之下,觀察風力係數與風壓係數的變化。風壓量測實驗,主要是利用量測纜索斷面在平滑流場下之風壓數值,再利用壓力積分成外力後便可得到纜索斷面所受的外力,經由數值計算便可得到所欲求的風力係數,經由探討風力係數之結果,可以觀察出纜索受力之行為,本實驗並針對不同纜索傾斜角度探討其角度變化後的風力係數之趨勢。
    斜拉索傾角為纜索與橋塔所夾的角度,斜拉索在風向平行於橋軸迎風面0度角風壓與文獻吻合,隨著斜拉索傾角越傾斜會使得最大平均壓力係數下降,風向平行於橋軸的纜索表面壓力會隨著纜索越傾斜而使表面平均壓力上升,風向垂直於橋軸的情況則剛好相反,而分離點並不隨著傾斜角而變化。
    在風力係數部分,平行於橋軸傾斜角度的拖曳向風力係數值會隨著斜拉索越傾斜而變小。基本上,圓形斷面受流體作用,因其斷面之對稱性,使得垂直向風力係數值趨近於0。當垂直於橋軸風向纜索傾斜時,背壓會明顯的增大,所以垂直於橋軸風向纜索的拖曳向風力係數值會隨著斜拉索越傾斜而變大。
    The objective of thesis is to study the aerodynamic coefficients of inclined cables of cable-stayed bridges by using pressure measurements. The cables were modeled by circular cylinders which were tested in smooth flow in wind tunnel. The drag and lift coefficients were obtained by integrating the wind pressure around the cable. The effects of inclined angles on the aerodynamic coefficients and wind pressure were investigated. Both the cases, wind parallel to and vertical to the bridge axis, were considered.
    The inclined angle of a cable defined here is the angle between the vertical tower and the cable. It can be observed that the pressure distribution around a cable is consistent with that in the literature as the angle is zero. In the case of wind being parallel to the bridge axis, the drag coefficient of a cable decreases as the inclined angle increases. However, the trend is on the contrary in the case of wind being vertical to the bridge axis, that is, the drag coefficient of a cable increases with the angle. As for the lift coefficient, it is approaching to zero because of the symmetry.
    Appears in Collections:[土木工程學系暨研究所] 學位論文

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