변동풍력의 연직분포를 고려한 건축물의 풍하중 평가

류혜진(Ryu, Hye-Jin),신동현(Shin, Dong-Hyeon),하영철(Ha, Young-Cheol) 대한건축학회 2019 大韓建築學會論文集 : 構造系 Vol.35 No.7

The wind tunnel test makes it possible to predict the wind loads for the wind resistant design. There are many methods to evaluate wind loads from data obtained from the wind tunnel test and these methods have advantages and disadvantages. In this study, two of these methods were analyzed and compared. One is the wind load evaluation method by fluctuating displacement and the other is the wind load evaluation method considering vertical profile of fluctuating wind force. The former method is evaluated as the sum of the mean wind load of the average wind force and the maximum value of the fluctuating wind load. The latter method is evaluated as the sum of the mean wind load and maximum value of the background wind load, and the maximum value of the resonant wind load. Two methods were applied to the wind tunnel test to compare the evaluated wind loads according to the two methods, with a maximum difference of about 1.2 times. The wind load evaluated by the method considering vertical profile of the fluctuating wind force (VPFWF) was larger than the wind load evaluated by the method by fluctuating displacement (FD). Especially, the difference of the wind load according to the two methods is large in the lower part of the building and the wind load is reversed at a specific height of the building. VPFWF of evaluating resonant wind loads and background wind loads separately is more reasonable.

변동풍력계수의 연직분포에 대한 특성

류혜진(Ryu, Hye-Jin),신동현(Shin, Dong-Hyeon),하영철(Ha, Young-Cheol) 대한건축학회 2022 대한건축학회논문집 Vol.38 No.10

The HFFB(High Frequency Force Balance) technique can easily obtain the shear force, the overturning moment, and the torsion moment of building. However, there is a blind point that the vertical profile cannot be grasped. The actual wind load does not act as the same force depending on the height direction of the building. Therefore, the shear force at the base of the building calculated through the HFFB technique should be appropriately distributed vertically. The background wind loads are generated by the wind, and it is reasonable to follow the vertical profile of the fluctuating wind force coefficient. In this study, the vertical profile of the fluctuating wind force coefficient was investigated through the wind pressure test. The PIM(Pressure Integration Method) was used to convert the wind pressure data obtained through the wind pressure test into the wind force data. The study model are the rectangular building with aspect ratios of 0.2, 0.25, 0.33, 0.5, 0.66, 1, 1.5, 2, 3, 4, 5. The vertical profile of the fluctuating wind force coefficient for along-wind direction, across-wind direction, torsional direction according to the change of the aspect ratio was analyzed. As a result, it was confirmed that the vertical profile of the fluctuating wind force coefficient tends to become relatively constant as the wind direction goes from 0° to 45°(When wind direction and structural axis do not coincide).

풍동실험에 기초한 풍방향 가스트하중계수 경험식에 관한 연구

신동현,하영철 한국풍공학회 2023 한국풍공학회지 Vol.27 No.4

The method of evaluating the wind load generated in buildings has developed a lot from the past. Among them, there is a relatively simple method, the gust loading factor method. This is a method of evaluating the equivalent static wind load by multiplying the static wind load by the dynamic coefficient and is used in the standards of many countries. Dynamic coefficients include Gust Effect Factor(DGEF) and Gust Loading Factor(MGLF). DGEF is displacement-based and can be calculated through theoretical assumptions, but the process is somewhat complicated. MGLF is based on the overturning moment and can be calculated by measuring the overturning moment through wind tunnel tests, but it takes a lot of time and effort to construct basic data. Therefore, in this study, we compared and analyzed the tendency of the along-wind mean wind force coefficient CF, mean overturning moment coefficien CM, and fluctuating overturning moment coefficient CM required when calculating MGLF to change according to aspect ratios( ), side ratios(D/B), and surface roughness(α). Through this, empirical formulas for the along-wind mean wind force coefficient CF, coefficients related to mean overturning moment Cg, and coefficients related to fluctuating overturning moment Cg were proposed, and basic data for MGLF calculation were presented. 건축물에 가해지는 풍하중을 평가하는 방법은 과거로부터 많은 발전을 이루었다. 그 중 비교적 간단한 방법인 가스트하중계 수법이 있다. 정적풍하중에 동적계수를 곱하여 등가정적풍하중을 평가하는 방법으로 여러나라 기준에서 사용되고 있다. 동적계수는 가스트영향계수(Gust Effect Factor:DGEF)와 가스트하중계수가(Gust Loading Factor:MGLF)가 사용된다. DGEF는 변위 기반으로서 이론적인 가정을 통해 산출할 수 있는 반면 그 과정이 다소 복잡하고, MGLF는 모멘트를 기반으로 하며 풍동실험으로 전도모멘트를 측정하여 산정할 수 있지만 기초자료를 구축하는 것에 많은 시간과 노력이 소요된다. 따라서 본 연구에서는 MGLF 산정 시 필요한 풍방향 평균풍력계수CF, 평균전도모멘트계수CM, 변동전도모멘트계수 CM 가 다양한 형상비( ), 변장비(D/B), 지표면조도구분(α)에 따라 변화하는 경향을 비교 분석하였다. 이를 통해 풍방향 평균풍력계수 CF, 평균전도모멘트 관련 계수 Cg, 변동전도모멘트 관련 계수 Cg 의 경험식을 제안하여 MGLF 산정에 대한 기초자료를 제시하였다.

고층건축물의 비틀림방향 풍하중 평가를 위한 변동풍력계수 및 파워스펙트럼밀도계수의 제안

길용식,김동우,김하림,하영철 한국풍공학회 2007 한국풍공학회지 Vol.11 No.2

This study is to estimate the empirical formulae of torsional fluctuating moment coefficient and power spectral density, which is needed to estimate torsional response of tall buildings. In order to estimate empirical formulae, force balance tests have been conducted on 27 types of the rectangular prisms with various aspects ratios, side ratios and surface roughness in turbulent boundary layer flows. In this paper, empirical formulae of torsional fluctuating wind force are mainly analyzed as a function of the aspects ratios, side ratios and various roughness of buildings. 본 논문은 고층건축물의 비틀림방향 응답을 평가하기 위하여 필요한 변동비틀림모멘트계수와 변동비틀림모멘트의 파워스펙트럼밀도계수의 경험식을 제안한 연구이다. 이러한 경험식을 제안하기 위하여, 다양한 형상비와 변장비를 가진 27개의 각주형 모형을 제작한 후 노풍도을 다양하게 변화시켜 풍력실험을 실시하였다. 본 논문에서 비틀림방향 변동풍력의 경험식은 주로 건물의 노풍도와 형상비 그리고 변장비에 의하여 분석되어졌다.

Analysis of Unsteady Blade Forces in a Vertical-axis Small Wind Turbine

이상문,김철규,전석윤,알사지드,장춘만 한국수소및신에너지학회 2018 한국수소 및 신에너지학회논문집 Vol.29 No.2

In the present study, unsteady flow analysis has been conducted to investigate the blade forces and wake flow around a hybrid street-lamp having a vertical-axis small wind turbine and a photovoltaic panel. Uniform velocities of 3, 5 and 7 m/s are applied as inlet boundary condition. Relatively large vortex shedding is formed at the wake region of the photovoltaic panel, which affects the increase of blade torque and wake flow downstream of the wind turbine. It is found that blade force has a good relation to the variation of the angle of attack with the rotation of turbine blades. Variations in the torque on the turbine blade over time create a cyclic fluctuation, which can be a source of turbine vibration and noise. Unsteady fluctuation of blade forces is also analyzed to understand the nature of the vibration of a small wind turbine over time. The detailed flow field inside the turbine blades is analyzed and discussed.

고층건축물의 비틀림방향 풍력특성에 관한 풍동실험연구

길용식,김동우,정영배,하영철 한국풍공학회 2006 한국풍공학회지 Vol.10 No.2

본 연구는 고층건축물의 비틀림방향 응답을 평가하기 위하여 필요한 변동비틀림모멘트계수와 변동비틀림모멘트의 파워스펙트럼밀도의 특성을 확인하는데 목적이 있다. 이러한 특성들을 평가하기 위하여, 다양한 형상비와 변장비를 가진 52개 형상의 공탄성 각주형 모형을 제작한 후 노풍도를 다양하게 변화시켜 풍동실험을 실시하였다. 본 논문에서는 비틀림방향의 변동풍력의 특성을 간단히 설명하였다. 그리고 그 결과는 대부분 건물의 형상비와 변장비에 의하여 분석되었다. This study aims at ascertainment characteristics of torsional fluctuating moment coefficient and power spectral density, which is needed to estimate torsional response of tall buildings. In order to estimate characteristics, the wind tunnel tests have been conducted on 52 types aero-elastic model of the rectangular prisms with various aspects ratios, side ratios and surface roughness in turbulent boundary layer flows. In this paper, characteristics of torsional fluctuating wind force are briefly discussed and then these results were mainly analyzed as a function of the aspects ratios and side ratios of buildings.

고층건축물의 비틀림방향 변동풍력의 특성에 관한 실험적 연구

하영철(Ha Young-Cheol),김동우(Kim Dong-Woo),길용식(Kil Yong-Sik) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

This study aims at verifying characteristics of torsional fluctuating moment coefficient and power spectral density, which is needed to estimate torsional response of tall buildings. In order to estimate characteristics, the wind tunnel tests have been conducted on 52 types aero-elastic model of the rectangular prisms with various aspects ratios, side ratios and surface roughness in turbulent boundary layer flows. In this paper, characteristics of torsional fluctuating wind force are briefly discussed and then these results were mainly analyzed as a function of the aspects ratios and side ratios of buildings.

풍동실험에 기초한 풍방향 풍하중의 특성고찰

최운호(Choi Un-Ho),황성권(Hwang Sung-Kwon),길용식(Kil Yong-Sik),하영철(Ha Young-Cheol) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

This study survey the characteristics of along-wind loadings based on wind tunnel test. To analyze along-wind loading, the High Frequency Force Balance Tests have been conducted on 27 types aero-elastic model of the rectangular prism with various aspect ratio, side ratio and surface roughness in turbulent boundary layer flows. In this study, expression of along wind loading are mainly analyzed as a function of the aspects ratios, side ratios and various roughness of buildings.

풍동실험에 기초한 풍방향 풍력 특성에 관한 연구

최운호,황성권,길용식,하영철 대한건축학회지회연합회 2007 대한건축학회지회연합회 학술발표대회논문집 Vol.2007 No.1

This study survey the characteristics of along-wind loadings based on wind tunnel test. To analyze along-wind loading, the High Frequency Force Balance Tests have been conducted on 27 types aero-elastic model of the rectangular prism with various aspect ratio, side ratio and surface roughness in turbulent boundary layer flows. In this study, expression of along wind loading are mainly analyzed as a function of the aspects ratios, side ratios and various roughness of buildings.

유체-구조물의 상호작용 알고리즘을 적용한 막구조물의 해석

예지현,한상을 大韓建築學會 2008 大韓建築學會論文集 : 構造系 Vol. No.

Membrane structures which behave large deformation are apt to vibrate and sensitive to the dynamic load. Wind is main factor for the membrane structure's behavior and affected by its behavior. Thus, it is adequate to consider fluid-structure interaction to analyze membrane structures which are having less rigidity more accurately. In this paper, we applied FSI analysis considering fluid-structure interaction on membrane structures. ADINA as finite element analysis program is used for dynamic analysis of structure and fluid analytical results of FSI are compared with those of CFD. As compared with FSI and CFD results, we find that the effects of fluctuating air force which have influence on stress, pressure and velocity of fluids owing to structure's response can not be ignored. And these differences of results will grow up when it comes to actual large span structure.