單摺版式屋頂之低層廠棚建築風載重特性研究

A Study on the Wind Effects on the Low-rise Industrial Buildings with Gable Roofs

本研究針對具有單摺版式屋頂之低層廠棚建物模型進行一系列的氣動力實驗，利用多頻道電子式壓力掃描器量測低層建築物表面風壓資料，控制包括模型的幾何尺寸比、屋頂斜度、風攻角等條件，實驗進行之初並與美國TTU 實場觀測資料進行驗證實驗，以確認實驗方法及可信度。量測所得屋頂各局部之表面風壓分佈在型態上呈現近似的分佈型態，上游區域有強烈的擾動及高尖峰值，下游屋頂面則呈現較為均勻分佈，水平攻角來流存在時，促使尖峰值大幅提昇。表面風壓分佈情形顯示，建物屋頂面上的風壓擾動分區採用側牆高度是合適的尺度。本研究同時利用正交模態分析法（POD） 分析屋頂面擾動性風壓分佈的模態，顯示在高度擾動的壓力分佈場內，POD 分析方法仍可有效的辨識出主要基本模態。本文同時考慮建物為簡單剛性構架的結構型態，利用相關性積分法，分析屋頂與樑柱系統間接合處的彎矩係數，由分析結果顯示，最大彎矩係數以上游邊側最高，特別是斜向風攻角作用下，不對稱來流作用，使剛構架內彎矩係數有上昇的趨勢。

A series of aerodynamic experiments of low-rise building models with gable roofs are conducted to investigate the wind loading characteristics under wind action. The pressure measurements were made by the electronic scani-valves system. The depth-to-height ratio, slope of roof and angle of attack of approaching flow were controlled conditions in these experiments. In the first stage of study, the data that collected from experiments was compared with the TTU real field data for validation. The results shown, the distributions of pressures on the roofs of each model are quite similar. The pressure characteristics on the upstream zone are high fluctuation and large peak, and the downstream zone are uniform relatively. The variation of angle of attack for approaching flow will increase the peak in the upstream corner of buildings. With the fluctuation distribution on the surface of model, taking the height of building as characteristic of zone scale is suitable. The proper orthogonal decomposition method (POD) is adopted to analysis the eigen-modes and eigen-values of fluctuating pressure fields. The results shown, the POD is a suitable method to identify the most likely mode shape of the high fluctuating pressure fields. The moment coefficients of beam-column connections of frames were estimated by the covariance integration method. We found that the maximum moment coefficients of frames will appear on the upstream corner. Especially with a small angle of approaching flow, the moment coefficients of frames will be increased for the asymmetric flow field actions.