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研究生:蔡孟緯
研究生(外文):Tsai, Meng-Wei
論文名稱:高層建築振動耦合之氣彈力現象風洞研究
論文名稱(外文):Wind Tunnel Investigation on the Motion Coupled Aeroelastic Behavior of Highrise Buildings
指導教授:鄭啟明鄭啟明引用關係
指導教授(外文):Chii-Ming Cheng
學位類別:碩士
校院名稱:淡江大學
系所名稱:土木工程學系
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:1996
畢業學年度:84
語文別:中文
論文頁數:121
中文關鍵詞:風洞氣彈力高層建築振態耦合
外文關鍵詞:Wind tunnelAeroelastichighrise buildingmode coupling
相關次數:
  • 被引用被引用:5
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論文提要內容:本文以方柱氣彈力模型實驗,考慮了順風向、橫風向以及
扭轉向等三個方向的變位,選出二種阻尼比的高層建築,而以扭轉向自然
頻率(fz)為控制變因,觀察不同之頻率比(fz/fy)對順、橫風向位移反應
之影響情形,此外,對於當結構物模型本身具有偏心時,也作了一般性的
探討。 對於順、橫風向振動耦合之動態位移反應預測,本文以靜止模
型所得之風力頻譜,配合三方向振態耦合計算而得。計算所得之順風向擾
動位移隨頻率比接近或偏心增大而呈現放大(1~5(倍))。而橫風向擾動位
移亦為如此(放大1~2(倍))。不偏心時,頻率比本身並不造成結構耦合,
故順風向及橫風向反應均無放大的現象。 雙軸向氣彈實驗結果顯示:
順風向反應並無明顯之氣彈力效應。橫風向反應在BL1流場、低阻尼結構
,於臨界風速會有負值氣動力阻尼出現,而使位移反應大增;在BL2流場
則無共振現象。而三軸向氣彈實驗結果為:順風向之平均位移反應(mean)
與二方向氣彈實驗幾乎一樣;而其擾動位移反應(rms),只當在某些特殊
案例(如頻率比FR=1.1 及偏心Ex=20%)才在臨界風速附近有放大(約2倍)的
現象,但此仍與預測結果(放大可達5倍)有相當之差距;橫風向擾動位移
反應隨頻率比愈接近1.0或偏心愈大而逐漸縮小(BL1流場與BL2流場均為如
此)。 在結構振動與尾跡渦散方面,BL1流場中雙軸向低阻尼氣彈實
驗(71LC實驗)之風速頻譜,在臨界風速時,渦散尖峰值極為陡峭,顯示出
有極強烈的橫風向振動與渦散間的共振現象,導致鎖定現象的發生。且當
逐漸靠近臨界風速時,橫風向位移與渦散間之交相關變得很高。都巿地形
中之二方向低阻尼實驗(72LC實驗)在所有風速之尖峰值均不明顯。此外,
純扭轉實驗因模型沒有水平向之擾動,故其尾跡渦散強度幾乎不改變而與
低風速時相同。在開闊地形之三軸向低阻尼氣彈實驗中,其尾跡渦散隨偏
心增加或頻率比接近1.0而逐漸減弱。同時,橫風向位移(y)與渦散(u)之
交相關性也 在此時漸漸變差,因此造成橫風向位移反應減小。關鍵字
:風洞,氣彈力,高層建築,振態耦合
Abstract: Aeroelastic model tests of a square cylinder were
performed to study the alongwind,acrosswind and torsional
responses of a highrise buildings. The frequency ratio between
lateral and torsional motion, and building eccentricities were
chosen to be experimental parameters to study their effects on
building responses. The building responses under mode
coupling based on wind force spectra obtained from stationary
pressure model measurements, were calculated to be the basis of
later comparison. The calculated results indicated that the
alongwind and acrosswind reponses would be amplified several
times due to the mode coupling effect caused by frequency
similarity and eccentricity. Bi-lateral mode aeroelastic
model tests showed that the alongwind response has little
aeroelastic effect while the acrosswind reponses exhibited
significant negative aerodynamic damping effects in BL1 and
cause large structural response. The alongwind mean responses of
triple-mode (2 lateral, 1 torsional) aeroelastic model tests are
same as bi-lateral model tests. The alongwind dynamic response
of triple-mode model show slight magnification in the large
eccentricity and unit frequency ratio case. The acrosswind
responses of triple-mode model show significant reduction in the
strong mode coupling situation which is exactly the opposite of
the calculated results. The characteristics of vortex
shedding were measured to verify the surprising acrosswind
behavior of mode-coupling aeroelastic model. During the bi-
lateral model tests, wake flow shows evident lock-in phenomenon
due to resonance between model vibration and vortex shedding,
resulting in high cross-correlation coefficience between wake
flow and model''s acrosswind motion. However, during the triple-
mode testing, the resonance between wake flow and model motion
were diminished when mode coupling effect become severe. Mean
while the correlation between wake flow and acrosswind motion
become insignificant.key word:wind tunnel,aeroelastic,
highrise building,mode coupling
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