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.
