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    題名: 高寬比7之矩形斷面高層建築橫風向之氣動力參數識別
    其他題名: Identification of aerodynamic coefficient of high-rise buildings with rectangular shapes of aspect ratio 7 in across-wind
    作者: 黃雍勛;Hung, Yung-hsun
    貢獻者: 淡江大學土木工程學系碩士班
    吳重成;Wu, Jong-Cheng
    關鍵詞: 高層建築;橫風向;直接預測法;鎖定;氣動力參數;high-rise building;Across-Wind;Direct Prediction Method;Lock-in;Aerodynamic Parameters
    日期: 2011
    上傳時間: 2011-12-28 18:44:30 (UTC+8)
    摘要: 當結構反應與風場形成互制時,對結構安全將造成嚴重威脅。對於高層
    建築而言,建築物高度越高,其擺動的自然頻率就越低,而因風力振動之頻
    率較低,較易與高樓產生共振,在設計時應盡量避免。本研究利用非線性自
    限運動理論模式,藉由三維高層建築之風洞試驗橫風向反應量測,探討及識
    別在平滑流場下其鎖定(Lock-In)共振時之線性氣動力阻尼、非線性氣動力阻
    尼及氣動力勁度三項參數,並建立氣動力參數資料庫。
    本研究利用直接預測法理論,假設其高層建築為單一自由度,配合實
    驗,進行不同斷面建物在共振鎖定時,使用追蹤共振法之遞增共振法識別氣
    動力參數識別,模型使用三組相同高度(70 ㎝)但不同矩型斷面進行識別實
    驗,分別為正方形斷面(BD1)、矩形斷面(BD1/2)及矩形斷面(BD1/3)。
    各種斷面以三種轉動慣量及三種阻尼比分類,模型BD1 進行了轉動慣量(低、
    中、高)及阻尼比(低、中、高)九種組合的試驗,模型BD1/2 及模型BD1/3
    由於在阻尼比0.75%以上時,產生振幅的反應極小,故僅進行了轉動慣量
    (低、中、高)及阻尼比(低、中)六種組合的試驗。
    實驗振幅反應顯示,在模型BD1 三種轉動慣量及三種阻尼比試驗中,皆
    在無因次化風速9.2 到9.8 之間進入鎖定現象,而中、高阻尼比試驗在無因
    次化風速較高時會有脫離鎖定現象情形,但在小阻尼比試驗時,大振幅反應
    在高無因次化風速仍持續發生,此現象可能已伴隨著馳振(Galloping)狀態。
    而模型BD1/2 及模型BD1/3 三種轉動慣量及兩種阻尼比試驗中,皆在無因次化
    風速5 到7 之間進入鎖定現象,其高阻尼比試驗雖因振幅微小但在高無因次
    化風速也有脫離鎖定現象情形發生,然而在低阻尼試驗中,因風速提高時,
    造成彈簧斷裂而無法提高風速,使其之後反應無法量測進行識別。實驗氣動
    力參數顯示方面,模型BD1 的三種氣動力參數,Y1隨著無因次化風速提高而減
    小,在高轉動慣量及高阻尼比試驗中,Y1減小後會在增大,ε隨著無因次化
    風速提高而減小,其在中、高阻尼比試驗中,ε減小後會在增大,Y2參數情
    形跟Y1相同。模型BD1/2 及模型BD1/3 隨著無因次化風速增加氣動力參數有其
    不同的趨勢。
    When the excessive structural response is interacted with the wind flow and thus the so-called
    aero-elasticity forms, the structural safety will become of great concern to engineers. Higher
    building have the lower natural frequency of oscillation for High-rise building, and wind power the
    lower frequency simple with the high-rise buildings of resonance, so that lock-in resonance effect in
    the across-wind motion of high-rise buildings should be mostly avoided.
    The aerodynamic parameters of the building models with different section shapes near the
    lock-in stage were successfully identified by using the direct prediction method, and the results can
    serve as the database for practical application. the identification tests were conducted in the wind
    tunnel by using three building models of the same height(70 ㎝)but different section shapes. They
    are square section(BD1), rectangular section (BD1/2) and rectangular section (BD1/3). The model
    BD1 was categorized in three sets of different combinations of mass moments of inertia (low,
    medium and high) and three sets of damping ratios (low, medium and high). The model BD1/2 and
    BD1/3 were categorized in three sets of different combinations of mass moments of inertia (low,
    medium and high) and two sets of damping ratios (low and high), because in these two cases the
    steady state response did not occur at the damping ratio above 0.75%.
    The resonance effect of the model BD1 starts to occur at the reduced velocity of about nine
    point two For the case with medium and high damping ratios, the resonance and lock-in effect cease
    at different reduced velocities. For the case with low damping ratio, the resonance amplitude keep
    increasing as the reduced velocity increases. The models BD1/2 and BD1/3 when wind speed
    increases will result spring break in the low damping. The three aerodynamic parameters (Y1,εand
    Y2) of the model BD1 BD1/2 and BD1/3 are completely different.
    顯示於類別:[土木工程學系暨研究所] 學位論文

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