一般而言，在探討橋梁氣動力行為時，主要以建構在平均風向與橋梁主軸正交的情況下。但就實際風場而言，平均風向鮮少正交於橋軸，且有些研究指出，在某些案例中，當在特定風向角與風攻角下橋梁之氣動力反應會比零風向角時來得顯著。
    本文主要經由一系列之斷面模型實驗與數值分析，來探討橋梁在斜風狀態下之氣動力行為。其中斷面模型主要以寬深比為5與10之斷面，而斷面模型實驗主要包括風力係數與顫振導數、顫振臨界風速、抖振反應之量測。經由實驗與數值分析來探討風向角之影響。
    由實驗結果得知，寬深比為5之斷面模型，其最低顫振臨界風速發生在負攻角且0度風向角之時。而寬深比為10之斷面模型，其最低顫振臨界風速發生在負攻角且20度風向角之時。以0度風攻角案例而言，實驗及數值結果均顯示顫振臨界風速係隨著風向角之增加而增加，其抖振反應則隨著風向角之增加而遞減。

In general, the investigations of aerodynamic behavior of bridges were established based on the assumption that the mean wind direction was normal to the longitudinal axis of bridge decks. In fact, the mean wind direction is rarely orthogonal to the bridge axis. Furthermore, some studies indicated that the aerodynamic responses of bridges under special wind direction and wind angle of attack maybe more significant than those in the case of zero angle of wind direction.
  This paper aims to study the aerodynamic behavior of bridges under skew wind by performing a series of section model tests and a numerical analysis. Two types of deck cross sections, with the width-to-depth (B/H) ratios of 5 and 10, were used in the test and the numerical analysis. The section model tests included measurements of the aerodynamic coefficients and flutter derivatives, the flutter critical wind speeds, and the buffeting responses. The effects of yaw angles were investigated both in the tests and in the numerical analysis. 
  The experimental results show that for the section model with B/H ratio of 5, the lowest flutter wind speed occurs at a negative angle of wind attack and a zero yaw angle. For the section model with B/H ratio of 10, the lowest flutter wind speed occurs at a negative angle of wind attack and a yaw angle of 20 degrees. Both the experimental and numerical results indicate that in the case of zero angle of wind attack, the flutter critical wind speeds increase with the yaw angles and the buffeting responses decrease as the yaw angles increase.

目錄	I
表目錄	V
圖目錄	VI
第一章  緒論	1
1.1  前言	1
1.2  研究動機與目的	2
1.3  研究內容	2
1.4  論文架構	3
第二章  文獻回顧	5
2.1  前言	5
2.2  橋梁風力效應	5
2.2.1  顫振效應(Flutter)與顫振導數	5
2.2.2  抖振效應(Buffeting)與風力係數	8
2.2.3  扭轉不穩定(Torsional instability)	9
2.2.4  渦流振動(Vortex shedding)	10
2.2.5  風馳效應(Galloping)	11
2.3  橋梁斷面形狀	12
2.3.1  流線型與非流線型	12
2.3.2  斷面寬深比	13
2.3.3  擾流板之影響	13
2.4  MITD簡介與顫振導數識別	15
第三章  流場、模型、實驗架構與流程及實驗結果	20
3.1  前言	20
3.2  流場介紹	20
3.3  風洞實驗室與儀器介紹	22
3.3.1  風洞實驗室的特性	22
3.3.2  皮托管 (Pitot Tube)	22
3.3.3  壓力轉換器	23
3.3.4  三維風速計(Cobra Probe)	24
3.3.5  雷射位移計	24
3.3.6  力平衡儀(Force Balance)	25
3.4  斷面模型製作	25
3.5  實驗架構與流程	26
3.6  斷面模型轉動慣量之量測	29
3.7  實驗結果	30
3.7.1  平滑流場下之顫振導數	30
3.7.2  平滑流場下之風力係數	35
3.7.3  平滑流場下之顫振臨界風速	38
第四章  數值模型分析	39
4.1  前言	39
4.2  斜風下顫振與抖振效應理論	39
4.2.1 橋梁運動方程式	39
4.2.2 顫振擾動力	42
4.2.4 橋梁顫振臨界風速分析方法	45
4.2.5 抖振效應之分析	50
4.3  相似性實驗	62
4.3.1  相似性轉換	62
4.3.2  相似性轉換公式推導	62
4.4  數值模型之建立	68
4.4.1  長跨徑橋梁之建立	68
4.4.2  數值模型之振態	68
4.5  數值分析之顫振臨界風速	69
4.6  數值分析之抖振反應分析	70
第五章  結論與建議	72
5.1  結論	72
5.2  建議	73
參考文獻	74

表目錄
表2.1 顫振導數代表之物理意義	80
表3.1 顫振臨界風速之量測 (U/ntB, nt為扭轉向自然頻率)	80
表4.1 本次實驗模型縮尺比例參數	81
表4.2 斷面模型與長跨徑橋梁結構性質比較	81
表4.3 主梁之斷面性質	81
表4.4 橋塔斷面性質	82
表4.5鋼纜(Cable)斷面性質	82
表4.6 長跨徑橋梁數值模型振態	82
表4.7 數值分析之顫振臨界風速 (m/s)	83

圖目錄
圖2.1 扭轉發散幾何示意圖	84
圖3.1 垂直向之紊流強度 8% 量測	85
圖3.2 水平向之紊流強度 8% 量測	85
圖3.3 儀器配置流程圖	86
圖3.4 斷面模型尺寸	86
圖3.5 實驗架構示意圖(1)	87
圖3.6 實驗架構示意圖(2)	87
圖3.7 風力係數量測轉換(1)	88
圖3.8 風力係數量測轉換(2)	88
圖3.9 風力係數量測轉換(3)	89
圖3.10 B/H=5 之 H_1^*	90
圖3.11 B/H=5 之 H_2^*	90
圖3.12 B/H=5 之 H_3^*	91
圖3.13 B/H=5 之 H_4^*	91
圖3.14 B/H=5 之 A_1^*	92
圖3.15 B/H=5 之 A_1^*	92
圖3.16 B/H=5 之 A_3^*	93
圖3.17 B/H=5 之 A_4^*	93
圖3.18 B/H=10 之 H_1^*	94
圖3.19 B/H=10 之 H_2^*	94
圖3.20 B/H=10 之 H_3^*	95
圖3.21 B/H=10 之 H_4^*	95
圖3.22 B/H=10 之 A_1^*	96
圖3.23 B/H=10 之 A_2^*	96
圖3.24 B/H=10 之 A_3^*	97
圖3.25 B/H=10 之 A_4^*	97
圖3.26 B/H=5 之 C_D	98
圖3.27 B/H=5 之 C_L	98
圖3.28 B/H=5 之 C_M	99
圖3.29 B/H=10 之 C_D	100
圖3.30 B/H=10 之 C_L	100
圖3.31 B/H=10 之 C_M	101
圖3.32 B/H=5 在平滑流場下 0°風向角之垂直向反應	102
圖3.33 B/H=5 在平滑流場下 0°風向角之扭轉向反應	102
圖3.34 B/H=5 在平滑流場下 10°風向角之垂直向反應	103
圖3.35 B/H=5 在平滑流場下 10°風向角之扭轉向反應	103
圖3.36 B/H=5 在平滑流場下 20°風向角之垂直向反應	104
圖3.37 B/H=5 在平滑流場下 20°風向角之扭轉向反應	104
圖3.38 B/H=5 在平滑流場下 30°風向角之垂直向反應	105
圖3.39 B/H=5 在平滑流場下 30°風向角之扭轉向反應	105
圖3.40 B/H=10 在平滑流場下 0°風向角之垂直向反應	106
圖3.41 B/H=10 在平滑流場下 0°風向角之扭轉向反應	106
圖3.42 B/H=10 在平滑流場下 10°風向角之垂直向反應	107
圖3.43 B/H=10 在平滑流場下 10°風向角之扭轉向反應	107
圖3.44 B/H=10 在平滑流場下 20°風向角之垂直向反應	108
圖3.45 B/H=10 在平滑流場下 20°風向角之扭轉向反應	108
圖3.46 B/H=10 在平滑流場下 30°風向角之垂直向反應	109
圖3.47 B/H=10 在平滑流場下 30°風向角之扭轉向反應	109
圖4.1(a) 抖振理論示意圖(側視圖)	110
圖4.1(b) 抖振理論示意圖(俯視圖)	111
圖4.2 橋面板第i節點自由度方向與編號示意圖	111
圖4.3 長跨徑橋梁之幾何圖形	111
圖4.4 B/H=5 T.I= 8% (垂直向)之相似率轉換	112
圖4.5 B/H=5 T.I= 8% (扭轉向)之相似率轉換	112
圖4.6 B/H=10 T.I= 8% (垂直向)之相似率轉換	113
圖4.7 B/H=10 T.I= 8% (扭轉向)之相似率轉換	113

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