高層建物受風影響之動力行為研究-實場監測與風洞試驗驗證II

Field measurements and wind tunnel validations of a tall building (II)

陳昶志(Chang-Chih Chen)

指導教授 ： 鄭啟明

淡江大學/工學院/土木工程學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00540

摘要

本文主要的重點為風工程實場量測相關技術之發展，主要目的在於建立起包含台灣氣候特徵（颱風）之結構受風反應與風場特性資料庫，做為風洞物理模擬數值模擬以及理論分析結果之最終驗證。並且做有關風洞實驗與實場量測間之比對與探討。
本研究於台北市辛亥路上百士大樓裝設速度計、加速度計與風速計，量測大樓在不同風速下之受風反應。並識別其自然頻率、阻尼，並統計該大樓於颱風時的動力反應。風洞實驗將透過嚴謹縮尺模擬一段長約4.2公里的發展段，分別以空氣動力實驗與空氣彈力實驗，量測其受風反應配合結構動力計算。求得特定風速下中央百世大樓之振動情形，並利用MIDAS軟體建立有限元素模型比較單自由度頻率域計算與多自由度直接街積分法差異並與實場監測結果比較。
本研究根據實場監測數據進行該建築之結構動力特性識別。結構阻尼在微振時與振幅有密切之正相關，結構振動較大時，會逐漸趨近1.2~1.4%之穩定值。高樓受風反應之機率函數為近似高斯之對稱鐘形分佈，其二軸向之峰態係數（Kurtosis）平均值分別為3.58 與 3.71。換言之，高樓受風反應之離散度較高斯分佈為低。其次，本文根據該建築施工藍圖建構有限元素模型，並以實場識別結構予以微調率定。完成後有限元素模型之二水平向之最低振態自然頻率與實測結果誤差均低於1%。本文針對該高層建築與其週邊環境進行嚴謹之風洞縮尺模擬，量測建築所受之風壓與風力。本文以氣動力試驗，試驗結果結合有限元素模型，分別進行頻率域及及時間域之結構受風反應分析並與實場量測比較驗證。根據風洞試驗結果進行頻率域及時間域分析所得到之速度反應相當接近，但略低於實場量測之數據。氣彈力實驗利用雷射位移計與力平衡儀量測該建築物受風時的反應。實驗結果。氣彈力實驗與氣動力實結果吻合十分良好。
研究結果充分顯示：在嚴謹縮尺條件下之風洞試驗可以有效的預測實場建物的受風反應。

關鍵字

實場監測 ； 風洞試驗 ； 結構識別 ； 颱風

並列摘要

This thesis is about the development of the wind engineering field monitoring. The final aim is to establish a wind engineering database on typhoon characteristics and its effects on tall buildings. This database will function as the final verification of physical wind tunnel simulations, computational fluid dynamics estimation and analytical predictions. Besides the field monitoring, wind tunnel tests were conducted for detailed comparisons.
In this investigation, a 30-story building located in Taipei City was instrumented with anemometers and accelerometers and velocity sensors. Wind characteristics and building behaviors under strong wind were monitored during several typhoons.
Tall building’s dynamic features, such as natural frequencies and damping were identified from the field data. Based on the original blue prints and field data, Finite Element model of the building was constructed and calibrated. Then, a series of carefully designed aerodynamic and aeroelastic wind tunnel tests were carried out. Wind loads obtained from aerodynamic tests were applied to the building F.E. model to evaluate the building dynamic responses and then compared with field data. Due to the scaling problem, the measurements of the aeroelastic tests were unable to be compared directly with the field data; therefore, they were compared with the F.E. model predictions.
The results indicate that the building responses based on wind tunnel test show good agreement with field measurements; and the aeroelastic test results agree well with the F.E. model predictions. This investigation has shown clear evidence that a well designed wind tunnel test can accurately predict the behaviors of a tall building under strong wind.

並列關鍵字

Field measurement ； Wind tunnel test ； typhoon ； structure identification

參考文獻

[57].池雅甯，高層建物受風影響之動力行為研究－實場監測與風洞試，淡江大學土木工程研究所碩士論文，台北(2007)

[2].Armitt, J. &Counihan, J. , 1968," The Simulation of the Atmospheric Environment ", Vol.2.﹐pp.49-71.

[3].Counihan﹐J. ,1970﹐" An Improved Method of Simulation Atmospheric Boundary Layer "﹐Atmospheric Environment﹐Vol.4﹐pp.159-275.

[4].Counihan﹐J.﹐1970﹐" Further Measurements in a Simulated Atmospheric Bounday Layer "﹐Atmospheric Environment﹐Vol.4﹐pp.159-275.

[5].Counihan﹐J.﹐1973﹐" Simulation of an Adiabatic Urban Boundary Layer in a Wind Tunnel "﹐Atmospheric Environment﹐Vol.7﹐pp.673-689.