干擾效應下的極值分佈特性

Interference effects on distribution feature of extreme pressures

曾育凡(Yu-Fan Tseng)

指導教授 ： 羅元隆

淡江大學/工學院/土木工程學系碩士班/碩士(2017年)

https://doi.org/10.6846/TKU.2017.00894

摘要

現今科技日益進步，隨著人口急速增長，土地資源的緊缺，使得都會區的建築物不斷向上發展，加上我國處於多颱風及地震之地理位置，因此高層建築在設計上不僅要考慮到耐震，風力對結構物的影響是相當重要的一環。建築物高度超過一百公尺，因振動周期較長，對風的影響較為顯著，尤其地震力隨著高度的增加而降低，建築物的結構設計將受風力控制，屆時風載重的設計為重要的問題，而藉由縮尺風洞實驗，將設計風載重及其分佈估計更為準確，必能提高高層建築的安全性。
本研究以壓力量測法對高寬比6之矩柱模型進行表面風壓量測，其中包含31種不同干擾建物位置與不含干擾建物配置之實驗，觀察主要建物之風壓分佈變化，並繪製成累積機率密度分佈(非超越機率)的形式，以Reverse-Weibull函數擬合曲線之形狀參數，計算曲線的變異係數，另外根據局部設計風載重理論可知，在建築物使用週期的考量下，設計風載重的目標超越機率(設計百分比)由極值風速的機率密度分佈函數與極值風壓係數的累積機率密度分佈函數的乘冪所決定，因此可以推估每一個風壓孔的最佳設計百分比及最佳設計風壓係數，並與國外規範中常見以Cook-Mayne值作為設計的結果進行比較。一般來說，Cook and Mayne(1985)所提出的78%非超越機率設計百分比是基於Gumbel分佈曲線的假設；若以本研究所得到的結果而言，局部風載重的設計值會隨著不同極值分佈曲線而有所調整，才能得到較合理的設計值。此外，非超越機率的分佈曲線呈現非高斯的特性與我國規範假設不同，透過本實驗能增加干擾效應下之氣動力資料，有利於我國建築耐風設計規範的修訂。

關鍵字

極值風壓 ； 非超越機率分布 ； Reverse-Weibull函數 ； 形狀參數 ； 設計風載重理論

並列摘要

With the rapid growth in construction technology and increasing population in the metropolitan area, high-rise buildings have been developed to reach higher and higher altitude. However, Taiwan island is located in a typhoon and monsoon sensitive area. It is important to consider not only the earthquake excitations but also the strong wind effects. When the building height is over 100 meters, the resistant wind load design is even prior to earthquake load. By means of physical scaling test, it is promising a more reliable safety design for high-rise buildings.
In this study, pressure measurement method is adopted for a square prism high-rise building model with aspect ratio of 6. There are in total 31 interference effect cases and one isolated case included. Local surface pressures are recorded for 100 field scale hours in order to examine their extreme value distributions and identification by Reverse-Weibull function. Based on the basic design wind load theory, the optimum design fractile for each pressure is found and its associated optimum design pressure coefficient is decided and compared to the design value based on Cook and Mayne concept. It is suggested from this study that Cook and Mayne coefficient is conservative for high-rise buildings with or without the interference effects.

並列關鍵字

Extreme wind pressure ； Non-exceedance probability distribution ； Reverse-Weibull distribution ； Shape parameter ； Design wind load theory

參考文獻

[19] 林倚仲，2005，“干擾效應對高層建築設計風力的影響”，淡江大學土木工程研究所碩士論文。

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