Approximation of Fluctuating Pressure Spectra of Dome-like Roofs Under Turbulent Flow

機構典藏 > College of Engineering > Graduate Institute & Department of Civil Engineering > Journal Article > Item 987654321/107104

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Title:	Approximation of Fluctuating Pressure Spectra of Dome-like Roofs Under Turbulent Flow
Other Titles:	半圓頂型屋蓋結構於紊流邊界層下擾動風壓頻譜之模擬
Authors:	Yuan-Lung Lo
Keywords:	半圓頂型屋蓋結構;風洞實驗;風壓頻譜;hemispherical dome;wind tunnel test;pressure spectrum
Date:	2016-03-01
Issue Date:	2016-08-15
Publisher:	中國土木水利工程學會
Abstract:	大跨徑屋蓋結構常由於其多功能性及富有創意的造型而普遍為現在社會接受。然而由於此類結構物多為輕材質，因此於設計結構載重時，耐風設計甚至比耐震設計來得重要。而且由於此類結構物具有大跨度的屋蓋，屋蓋表面風壓分佈具有較差的空間相關性，因而導致風力載重的評估更加困難。屋蓋表面的擾動風壓頻譜在過去文獻中多有提及，然而卻未有系統性地、以基本結構參數進行探討，例如屋蓋高跨比、底座高跨比、或表面擾動風壓點的相對位置等。在本篇研究中，主要針對具有多組幾何變化的圓頂型屋蓋結構於一標準紊流地況中，其表面的擾動風壓頻譜進行探討。本篇內容首先以屋蓋高跨比及底座高跨比，做為探討平均風壓係數及擾動風壓係數於表面的分佈情形，以了解整體風壓分佈的基本特性。然後提出一個廣義的擾動風壓頻譜模型，用以模擬擾動風壓頻譜於圓頂型屋蓋表面上隨著上下游而改變的情形。藉由採用權重因子的概念，以及基於實驗結果所觀察到的現象給予合理性的假設，此一廣義性的擾動風壓頻譜模型可普遍提供一良好的近似結果，顯示出擾動風壓頻譜隨上下游變動的趨勢；而對於單點的擾動風壓頻譜亦表現出不錯的近似結果。 Large span roof structures have been widely adopted for their good performance in multiple functionalities and innovative designs. However, because of its light weighted feature, wind resistant design is more prior to the earthquake design. And further, its long span geometry often results in a weak spatial correlation in pressure distributions and hence makes the estimation of wind loads a difficult task. Spectrum characteristics of wind pressures have been mentioned in several publications; however, there is no systematic discussion in terms of basic parameters, such as the ratio of roof rise to roof span, the ratio of base wall height to roof span, or the location over the surface. In this paper, power spectra of fluctuating wind pressures on various dome-like roofs are investigated under a suburban terrain flow. By examining the mean and RMS pressure coefficients, basic flow patterns are demonstrated in terms of the rise/span and wall-height/span ratios. Then the general approximation model was proposed to simulate the variations of power spectra of fluctuating pressures over the dome-like roofs. By the weighting factor concept and based on reasonable assumptions, the general approximation model reproduced fairly good agreements in describing the overall tendencies and acceptable spectra at individual locations.
Relation:	中國土木水利工程學刊=Journal of the Chinese Institute of Civil and Hydraulic Engineering 28(1), p.11-19
Appears in Collections:	[Graduate Institute & Department of Civil Engineering] Journal Article

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