臺灣博碩士論文加值系統

高層建築所承受的風載重，可分為順風向、橫風向及扭轉向三組同時作用的風力。其中之順風向風力是由風速壓與逼近流的紊流特性所決定，基本上可透過準穩定定理與條狀理論合理的進行預測，因此各國風力規範中之相關條文大致接近。至於橫風向及扭轉向風力則是因為渦散分離及紊流尾跡等現象，產生橫向不平衡風壓及不對稱風壓所造成，因為其學理較為複雜，目前仍不易以合適之解析模式或半經驗模式合理預測。
在目前台灣規範中，根據結構頻率與流場紊流特性計算而得之順風向陣風反應因子，在建築物高度上之分布為一固定值。然而對於柔性建築物之設計風載重而言，其風力之擾動部份佔整體風力之比重相當大，然而其在高度上之分配方式接近慣性力之分布，與平均風力及擾動風力之背景部份明顯不同。因此本文根據風工程界近年來之研究成果，針對高層建築順風向設計風力之計算式提出修正方案，使其能更正確的反應柔性建築結構的動力特性。同時，本文亦藉由一系列之風洞試驗，進行風載重修正方案所需風力參數之量測。
根據風洞實驗觀測結果提出順風向設計風力修正模式，包含下列假設：(1)假設迎風面之平均風力及擾動風力在高度上分佈遵循條狀定理與準穩定理論；背風面風力則為均勻分布；(2)擾動風力之背景部份引入折減因子以適度考慮空間相關性的影響；(3)共振部份之設計風力依慣性力進行高度上的分配。
本文參考目前國內風力規範對於橫風向及扭轉向風載重使用條件之幾何限制，設計一系列之風壓模型風洞試驗，以取得順風向設計風力修正模式中所需之氣動力參數。選取之模型斷面高寬比為3、4、5、6、7；深寬比為1/5、1/4、1/3、1/2、1/1、2/1、3/1、4/1、5/1，同時以現行規範定義之地況A、B、C為逼近流場，進行建築物表面風壓之物理模擬風洞試驗。
文章最後以數值分析計算6棟不同幾何外型之建築物，在台灣規範定義之3種地況對應之逼近流場作用下，其順風向之等值設計風載重。其中選取之建築物斷面高寬比為3及6，深寬比為1/3、 1/1、 3/1，建築物高度分為90公尺及180公尺。評估風載重之方式包括本文推導之半經驗式及台灣現行風力規範，並以風洞實驗歷時風力資料進行之結構分析結果，做為二者分析結果之比較之標準。計算結果顯示，本文推導公式在地況A及B較目前風力規範更能有效反應風洞試驗之評估結果，而在地況C則有偏低之趨勢。該結果說明本文對於風載重之假設，以及據此推導所得之評估模式，能合理表達真實建築物之設計風載重分布情形與數值大小。

The wind loading of a tall building can be divided into three components: alongwind, acrosswind and torsional wind loads. For the alongwind load, it is induced by the mean wind speed pressure and the turbulence characteristics of the approach flow. It is generally accepted that analytical model basing on quasi-steady theorem and strip theory can adequately predict the alongwind loading, and thus it was adopted by many building wind codes. As for the acrosswind and torsional wind loads, they are mainly induced by the wake flow. The mechanisms are complicated and can not be adequately modeled by analytical or semi-empirical models.
For the present Taiwan building wind code, the Gust Response Factor used in the alongwind design wind load is fixed-value calculated, based on the structure natural frequency and turbulence characteristics. Nevertheless, for a flexible tall building, the dynamic resonant part of the response plays a significant role in the design wind load. It is observed that the spatial distribution of the resonant part loading is different from the mean wind load and dynamic background part wind load. Hence, this project investigates the appropriateness of the current alongwind design wind load practice for a flexible tall building, and provides an alternative with a more precise procedure. This search also implemented a series of wind tunnel testing to measure the tall buildings’ wind loads in turbulent boundary layers designated by the current Taiwan building wind code.
A modified procedure for alongwind design wind load is proposed with the following conditions: (1)The mean and dynamic wind forces on the windward face follow the strip theory strictly; the wind forces on the leeward face assumed to be uniform; (2)The spatial correlation effect on the background part of equivalent static wind load is amended by a correlation reduction factor; (3)The resonant part is distributed based on the distribution of the inertia force.
In order to investigate a more clearer picture on wind load characteristics of rectangular shaped tall buildings, pressure models were established and tested in a boundary layer wind tunnel. Three turbulent boundary layer flows with power law index α=0.32, 0.25, 0.15, respectively, were created. The geometry variations of the pressure models in wind tunnel test are: aspect ratio 3, 4, 5, 6, 7; side ratios 1/5, 1/4, 1/3, 1/2, 1/1, 2/1, 3/1, 4/1, 5/1.
Numerical study is then performed on 6 different prototype buildings in 3 kinds of flow fields. The geometry variations of the buildings are: aspect ratio = 3, 6; side ratios D/B = 1/3, 1/1, 3/1 and the buildings’ heights are 90m and 180m. The equivalent static wind load based on the semi-empirical formulation is compared with the current Taiwan wind code and wind tunnel measurement. The outcome reflects that, in terrain A and B, the present design wind load model is closed to wind tunnel’s and is much more accurate than the present Taiwan wind code. But the present design wind load model is lower than wind tunnel results in terrain C. It’s shown that the assumptions of the wind load and the semi-empirical model using the assumptions are more precise procedures to evaluate alongwind design wind load of tall buildings.

第一章 緒論 1
1.1 前言 1
1.2 研究內容與方法 2
1.3 本文內容簡述 3
第二章 文獻回顧 5
2.1 風洞實驗之模擬 5
2.1.1 大氣邊界層之模擬 5
2.1.2 阻塞效應（blockage effcct ) 5
2.1.3 雷諾數效應 6
2.2 高層建築風洞實驗 6
2.2.1 深寬比對拖曳力係數之影響 7
2.2.2高寬比對拖曳力係數之影響 8
2.2.3紊流對順風向風力頻譜之影響 8
2.2.4紊流對順風向風力係數之影響 8
2.3 順風向設計風力 9
2.3.1. 位移陣風反應因子(Displacement Based Gust Loading Factor，DGLF) 10
2.3.2 彎矩陣風反應因子(Moment Based Gust Loading Factor，MGLF) 13
2.3.3 Solari 順風向反應模式 16
第三章 理論背景 20
3.1大氣邊界層 20
3.1.1平均風速剖面 20
3.1.2 紊流強度 21
3.1.3 紊流長度尺度（Length scales of turbulence） 22
3.1.4 縱向擾動風速頻譜 23
3.1.5 縱向擾動風速交相關頻譜（cross-spectra） 24
3.2 結構動力特性 25
3.3 風與結構體的相互關係 28
3.3.1 風流經結構體的特殊行為 28
3.3.2 風力作用下的位移反應計算 29
3.4 散漫數據分析 32
第四章 順風向等值設計風載重計算模式 34
4.1 基本假設 34
4.2 平均風載重 37
4.3 擾動風載重之共振部份 37
4.4 擾動風載重之背景部份 41
4.5 本文推導之等值靜態風載重總結 44
第五章 風洞試驗之儀器配置與量測分析 48
5.1 逼近流場 48
5.2 風壓模型 55
5.3 參考風速量測 57
5.4 實驗設備 58
5.4.1 風洞 58
5.4.2 量測儀器 59
5.5 訊號處理及數據分析 62
5.5.1.風壓訊號之管線修正 62
5.5.2 數據採樣技術 63
5.5.3 數據分析之方法 64
第六章 風洞試驗結果與討論 66
6.1 順風向風力 66
6.1.1 風力係數與相關文獻比較 67
6.1.2 重複實驗之誤差 68
6.1.3 模形幾何形狀對風力載重之效應 70
6.1.4 邊界層流場對風力載重之效應 78
6.2模型局部風力之特性 83

6.3模型風力於空間上之相關函數特性 85
6.3.1 弦向風壓相關函數(chord-wise coherence) 85
6.3.2 迎風面與背風面間之相關函數 88
6.3.3 徑向相關函數(Span-wise coherence) 90
第七章 設計風載重案例分析 93
7.1風洞實驗相關數據與結構物特性 93
7.2 風洞資料之等值靜載重歷時分析 95
7.3 不同分析方式之設計風載重比較 97
第八章 結論與建議 106
8.1 結論 106
8.2 建議 108
參考文獻 110

圖表目錄
表3-1 不同地況之指數率參數 21
表7-1 二種案例(高寬比3、6之方柱)之相關參數 94
表7-2 案例結構物在不同邊界層來流作用下之順風向風力相關參數 95
圖3-1 紊流長度尺度參數C、W和高度Z0關係圖 23
圖4-1 紊流場作用下之30層大樓順風向風載重 35
圖4-2 平均拖曳力係數CD與擾動拖曳力係數CD’在高度上之分佈 35
圖4-3 模型幾何尺寸及座標系統 36
圖5-1 錐形擾流板基座寬度與流場關係圖 49
圖5-2 粗糙元素幾何尺寸及配置 51
圖5-3 三種地況之錐形擾流板 52
圖5-4 都市地形(A地況) 邊界層模擬圖 53
圖5-5 大都市市郊或小市鎮地形(B地況) 邊界層模擬圖 53
圖5-6 開闊地形(C地況) 邊界層模擬圖 54
圖5-7逼近流場平均風速、紊流強度及長度尺度剖面 55
圖5-8 風壓模型幾何尺寸、風壓孔佈設位置及實驗配置 57
圖5-9 淡江大學一號邊界層風洞實驗室 59
圖5-10 IFA-300智慧型風速儀、探針及校正儀 59
圖5-11 壓力量測系統[文獻5-1] 60
圖5-12 壓力訊號處理系統(RADBASE3200)[文獻5-1] 61
圖5-13 64頻道壓力感應器模組[文獻5-1] 61
圖5-14 本文130cm風壓管之管線修正使用之頻率域轉換函數 63
圖6-1 Lin(2-24)風洞實驗之平均風速剖面與紊流強度 68
圖6-2 本文實驗結果與Lin[文獻2-24]在不同深寬比實驗之拖曳力係數比較圖(高寬比4 ) 68
圖6-3 基底平均及擾動拖曳力係數之個別實驗誤差 70
圖6-4 不同長寬比對平均基底拖曳力係數隨之影響. 71
圖6-5 不同長寬比對擾動基底拖曳力係數隨之影響 73
圖6-6 不同長寬比模型之順風向基底彎矩頻譜 76
圖6-7不同高寬比模型之順風向基底彎矩頻譜. 77
圖6-8 不同地況對平均基底拖曳力係數之影響 79
圖6-9 (a)(b)(c) 不同地況對擾動基底拖曳力係數之影響 80
圖6-9 (d)(e) 不同地況對擾動基底拖曳力係數之影響 81
圖6-10 不同流場之順風向基底彎矩頻譜. 82
圖6-11 不同長寬比模型迎風面局部之平均及擾動風力係數 ( =7). 84
圖6-12 不同長寬比模型背風面局部之平均及擾動風力係數( =7). 85
圖6-13 迎風面與背風面個別之弦向相關函數 (2/3 H, BL-B). 87
圖6-14 不同模型之最佳指數衰減係數 Cxw 及 Cxl (2/3H, BL-A). 87
圖6-15 不同模型之最佳指數衰減係數 Cxw 及 Cxl (2/3 H, BL-B). 88
圖6-16 不同模型之最佳指數衰減係數 Cxw 及 Cxl (2/3 H, BL-C). 88
圖6-17 迎風面與背風面間之相關函數(BL-B). 89
圖6-18 迎風面與背風面間之相關函數最佳之衰減係數CN. 90
圖6-19 徑向壓力相關函數 (BL-B). 91
圖6-20 徑向壓力相關函數最佳之指數衰減係數CZ. 92
圖7-1 深寬比1/3、高寬比3及6之MIDAS結構模式 96
圖7-2 地況C、深寬比1/1、高寬比6案例，不同歷時分析方法之等值靜態風載重之比較 97
圖7-3-1 深寬比1/3高寬比6地況A案例順風向設計風載重 100
圖7-3-2 深寬比1/1高寬比6地況A案例順風向設計風載重 100
圖7-3-3 深寬比3/1高寬比6地況A案例順風向設計風載重 100
圖7-4-1 深寬比1/3高寬比6地況B案例順風向設計風載重 101
圖7-4-2 深寬比1/1高寬比6地況B案例順風向設計風載重 101
圖7-4-3 深寬比3/1高寬比6地況B案例順風向設計風載重 101
圖7-5-1 深寬比1/3高寬比6地況C案例順風向設計風載重 102
圖7-5-2 深寬比1/1高寬比6地況C案例順風向設計風載重 102
圖 7-5-3 深寬比3/1高寬比6地況C案例順風向設計風載重 102
圖7-6-1 深寬比1/3高寬比3地況A案例順風向設計風載重 103
圖7-6-2 深寬比1/1高寬比3地況A案例順風向設計風載重 103
圖7-6-3 深寬比3/1高寬比3地況A案例順風向設計風載重 103
圖7-7-1 深寬比1/3高寬比3地況B案例順風向設計風載重 104
圖7-7-2 深寬比1/1高寬比3地況B案例順風向設計風載重 104
圖7-7-3 深寬比3/1高寬比3地況B案例順風向設計風載重 104
圖7-8-1 深寬比1/3高寬比3地況C案例順風向設計風載重 105
圖7-8-2 深寬比1/1高寬比3地況C案例順風向設計風載重 105
圖7-8-3 深寬比3/1高寬比3地況C案例順風向設計風載重 105

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[2-35]Solari, G. (1993a) “Gust buffeting I: peak wind velocity and equivalent pressure.” Journal of Structural Engineering, ASCE, Vol. 110, 2, 365-382.

[2-36]Solari, G. (1993b) “Gust buffeting II: dynamic alongwind response.” Journal of Structural Engineering, ASCE, Vol. 110, 2, 383-398.

[2-37]Solari, G. (1988) “Equivalent wind spectrum technique : theory and application.” Journal of Structural Engineering, 114(6), 1303-1323.

第三章
[3-1] Davenport,A.G., 1956 , "The Relationship of Wind Structure to Wind Loading", Proc. Symp. on Wind Effects on Buildings and Structures, Vol.1, National Physical Laboratory, Teddington, U.K. Her Majesty''s Stationary Office, London, p53-102.

[3-2] American National Standard A58.1-1982 Minimum American National Standard Institute, Inc., New York.

[3-3] Counihan, J., " Adiabatic Atmospheric Boundary Layers: A Review and Analysis of Data from the Period 1880-1972 ", Atmospheric Environment, Vol. 9, 1975, pp. 871-905.

[3-4] Davenport,A.G., 1961 ,"The Spectrum of Horizontal Gustiness Near the Ground in High Winds", J. Royal Meteorol. Soc., 87 , p194-211.

[3-5] Kaimal﹐J. C., 1972, "Spectral Characteristics of Surface Layer Turbulence " J. Royal Meterol Soc. ﹐Vol.87﹐pp.563-589.

[3-6]Holmes, J.D., (2001), Wind loading of structures, Spon Press.

[3-7] A. Kareem, 1981, “Wind excited response of buildings in higher modes”, J. Struct. Div., ASCE, vol. 107, no. ST4, pp. 701-706.

[3-8] B. J. Vickery,1970 , " On the Reliability of Gust Loading Factors ",Proc. Technical Meeting Concerning Wind Loads on Buildings and Structures,National Bereau of Standards Building Science Series 30,Washington, D. C. .

[3-9]A. G. Davenport,(1968), “The dependence of wind load upon meteorological parameters.”, in proceedings of the international research seminar on wind effects on buildings and structures, University of Toronto Press, Toronto, 19-82.

第四章
[4-1]鄭啟明, 蔡明樹, (2006)“高層建築順風向設計風載重之修正研究”, 中華民國第八屆結構工程研討會, Sep. 1-3, 2006.

[4-2]鄭啟明, 蔡明樹, (2007) , “高層建築順風向設計風載重分析模式與風洞實驗之研究”九十六年電子計算機於土木水利工程應用研討會.

第五章
[5-1]“RAD3200 System Instruction and Service Manual”, Scanivalve Corp.

第六章
[6-1]J. Vellozzi and E. Cohen, (1968),“Gust response factors.”, J. Struct. Div., ASCE, 94, no. ST6, Proc. Paper 5980, 1295-1313.