풍동실험을 통한 경량통신철탑의 풍응답 예측

조강표,타무라 유키오,이토 타카요시 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

Wind-tunnel experiments of a communication steel tower were conducted for the wind-induced response using a rocking model. A turbulent wind flow (II of AIJ Recommendation on Loads on Buildings) was generated to closely simulate full scale wind environments. Two different damping levels (0.4% and 1.0% critical damping), which were adjusted by a silicon damping device, were selected as target damping ratios to estimate wind-induced vibration of the prototype structure with and without a tuned mass damper (TMD). Wind-excited motions of the prototype structure (K Tower in Japan) recorded in a video type were also analyzed and compared with the results of the wind-tunnel tests. The experimental results have a reasonable agreement with the analyzed result of video images.

다양한 형상을 가진 초고층 건물의 내풍특성

김용철,타무라 유키오,Kim, Y.C.,Tamura, Yukio 한국전산구조공학회 2012 전산구조공학 Vol.25 No.1

인접건물에 의한 고층건축물의 피크국부풍압 분포 I - 피크풍압분포 및 풍압파워스펙트럼 중심으로 -

김원술,김윤석,타무라 유키오,요시다 아키히토 한국풍공학회 2011 한국풍공학회지 Vol.15 No.1

Local peak pressures between two buildings were studied by using wind tunnel experiments for various locations and height ratios of an interfering building and wind directions. The measured local peak pressure coefficients were compared to those obtained previously from a study on an isolated building. The experimental results have been examined and presented from the viewpoint of cladding design. The results show that at wind direction θ=135˚, minimum peak pressure coefficient on the front surface of the principal building with the interfering building for H_r≥1.5 at (S_x,S_y)=(1.5B,0) tends to increase generally and the smallest values of minimum peak pressure coefficients on the front surface of the principal building were -4.7(H_r=1.5), -5.7(H_r=2.0), while the smallest value of minimum peak pressure coefficient on the isolated building was -3.5. It can be explained by the fact that an increase in energies is associated with the reattaching shear layers on the principal building caused by high turbulence, thus significantly increasing the suction. 본 연구에서는 풍동실험을 통해 인접건축물의 다양한 높이비, 위치와 풍향에 따른 고층건축물에 작용하는 피크풍압계수에 대하여 조사하였다. 그리고 피크풍압계수는 Cook and Mayne의 제안식을 이용하여 산출하였다. 실험결과는 우선적으로, 인접건축물의 유무에 따른 최대 및 최소풍압계수의 분포도를 통해 비교 분석하였다. 풍동실험결과 풍향 135도에서 인접건축물의 높이비가 H_r≥1.5이고, (S_x,S_y)=(1.5B,0)에 위치할 때, 대상건축물의 정면에 작용하는 최소풍압계가 단독건축물에 작용하는 최소풍압계수(-3.5)에 비해 전반적으로 크게 나타났으며, 최소풍압계수의 최소값은 정면의 최상부 코너 부근에서 -4.7(H_r=1.5), -5.7(H_r=2.0)으로 나타났다. 본 연구의 결과는 CFD 해석 결과의 정당성 입증과 두동 이상으로 이루어진 고층건축물의 초기설계단계에서 상호간섭효과로 인한 외장재용 풍하중을 대략적으로 평가하는데 유용하게 사용할 수 있을 것이다.

상호간섭효과에 의한 고층건축물에 작용하는 국부풍압에 관한 연구

김원술(Kim Won-Sul),타무라 유키오(Tamura Yukio),요시다 아키히토(Yoshida Akihito) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.1

Most wind codes or standards have been established for isolated buildings. In real environment, the effect of wind load on a group of high-rise buildings could be quite different from that of isolated tall building and its surrounding tall buildings can either increase or decrease not only the whole wind load, but also wind loads locally affecting cladding. Some Wind Standards such as AIJ(2004), AS1170.2(1989) and ASCE7-05(2005) have incorporated design wind loads on buildings and cladding due to effects of mutual interference by neighboring and structures, but there is no concrete information. In this paper, local peak wind pressure coefficients between two identical tall buildings were studied by using wind tunnel experiments, under various locations of interfering buildings and wind directions. The measured peak wind pressure coefficients were compared with those previously obtained from the study of an isolated building. In addition, this study also investigated the interference effects of smallest minimum wind pressure coefficient under various wind angles. The interference effects were examined and presented in detail. The results show that the local peak wind pressure coefficients on the walls of a principal building largely depended on the wind angles and the location of interfering buildings in the wake region.

인접건축물이 고층건축물의 외장재용 풍하중에 미치는 영향

김원술(Kim Won-Sul),타무라 유키오(Tamura Yukio),요시다 아키히토(Yoshida Akihito) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.1

This paper describes results of wind tunnel experiments performed at Tokyo Polytechnic University to determine interference effects of local peak pressures on an identical pair of tall buildings to establish design cladding pressures. Measured local peak wind pressure coefficients were compared with those for the walls of an isolated building. The results showed the distribution of maximum (minimum) wind pressure coefficients on walls of a principal building with critical locations of an interfering building, as well as smallest minimum wind pressure coefficients on the side walls of the principal building due to interference. Also, the local peak wind pressure coefficients on the walls of the principal building were higher or lower depending on the locations of the interfering building, and were largely induced by the wake separated from the edges of an upwind interfering building. The authors deal with the shielding effects and channeling effects for various relative locations of the interfering building.

단면의 변의 수가 초고층 건물의 공력특성에 미치는 영향

김용철,반디 에스와라 쿠마,유키오 타무라,요시다 아키히또,윤성원,Kim, Yong-Chul,Bandi, Eswara Kumar,Tamura, Yukio,Yoshida, Akihito,Yoon, Sung-Won 한국공간구조학회 2013 한국공간구조학회지 Vol.13 No.3

A series of wind tunnel tests were conducted on 7 super-tall buildings with various polygon cross-sections, including triangle, square, pentagon, hexagon, octagon, dodecagon, and circular. The primary purpose of the present study is to investigate the effect of increasing number of sides on aerodynamic characteristics for super-tall buildings. Wind tunnel tests were conducted under the turbulent boundary layers whose power-law exponent is 0.27. Fluctuating wind pressures from more than 200 pressure taps were recorded simultaneously, and time series of overturning moments were calculated considering tributary area of each pressure tap. The results show that the overturning moment coefficients and the spectral values decrease with increasing number of sides, and the largest mean and fluctuating overturning moments were found for the triangular super-tall building, and the largest spectral values were found for the square super-tall building. The analysis should be conducted more in detail, but currently it can be roughly said that there seems to be a little differences in the aerodynamic characteristics for the super-tall buildings whose number of sides is larger than 5 or 6.

나선형 초고층건물의 공력불안정 진동과 공력감쇠에 관한 연구

김원술,아키히토 요시다,타무라 유키오,이진학,Kim, Wonsul,Yoshida, Akihito,Tamura, Yukio,Yi, Jin-Hak 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.1

본 논문에서는 변위응답 및 가속도 응답의 저감 효과에 있어서, 유리한 형상인 $180^{\circ}$ 나선형(Helical $180^{\circ}$) 초고층건물을 대상으로 풍진동실험을 수행하여 나선형 초고층건물의 공력불안정 진동 특성 및 공력감쇠 특성을 조사하였고, 정방형 초고층건물의 결과와 비교분석 하였다. 본 연구에서의 공력감쇠율은 RD법(random decrement technique)을 이용하여 평가하였다. RD법에 의해 평가된 공력감쇠율은 기존문헌 및 준정상가정이론 결과와 비교 검증하였다. 실험결과, 공력진동 실험결과 $180^{\circ}$ 나선형모형의 풍직각방향에 대한 공력불안정 진동은 발생하지 않는 것이 확인되었다. 정방형과 $180^{\circ}$ 나선형 형상에 대한 공력감쇠율을 살펴보면, X방향에 대한 공력감쇠율은 무차원 풍속이 증가와 비례하여 점진적으로 증가하는 경향이 나타났다. 반면, Y방향에 대한 공력감쇠율은 정방형모형과 매우 다른 양상이 나타나는 것을 알 수 있었다. In this paper, aeroelastic instability and aerodynamic damping ratio of a helical $180^{\circ}$ model which shows better aerodynamic behavior in both along-wind and crosswind responses on a super tall building was investigated by an aeroelastic model test, and the aerodynamic damping ratio was evaluated from the wind-induced responses of the model by using Random Decrement Technique. Aerodynamic damping ratios evaluated in this study were verified through comparison with previous results obtained by quasi-steady theory. As a result, the aeroelastic instability of the helical $180^{\circ}$ model in crosswind direction were not occurred for any conditions with increasing the reduced wind velocity while the square model generally encounters aeroinstability due to the vortex shedding. The aerodynamic damping in along-wind direction for the helical $180^{\circ}$ and the square model increased monotonically both with reduced wind velocity, i.e., there is no relation with modifications of building shapes. On the other hand, in crosswind direction, the characteristics of aerodynamic damping ratio with reduced wind velocity for helical $180^{\circ}$ model were quit different from those of the square model.

비정형 초고층 건물의 변동 풍압

김용철,칸다 준,타무라 유키오,윤성원,Kim, Yong-Chul,Kanda, Jun,Tamura, Yukio,Yoon, Sung-Won 한국공간구조학회 2013 한국공간구조학회지 Vol.13 No.1

Recent tall buildings tend to have unconventional shapes as a prevailing, which is effective for suppressing across-wind responses. Suppression of across-wind responses is a major factor in tall building projects, and the so called aerodynamic modification method is comprehensively used. The purpose of the present study is to investigate the pressure fluctuations on tapered and setback tall buildings, including peak pressures, power spectra and coherences through the synchronous multi-pressure sensing system techniques. And flow measurements around the models were conducted to investigate the condition of vortex shedding. The results show that by tapering and setback, different distributions of mean pressure coefficients at leeward surface were found, which is caused by the geometric characteristics of the models. And the power spectra of wind pressures at sideward surface become wideband and the peak frequencies are different depending on heights, which makes the correlation near the Strouhal component low or even negative. The differences in shedding frequencies were also confirmed by the flow fields around the models.

다양한 변장비를 가진 고층건축물에 작용하는 풍력의 상관 분석

김원술,요시다 아키히토,타무라 유키오,Kim, Wonsul,Yoshida, Akihito,Tamura, Yukio 한국전산구조공학회 2015 한국전산구조공학회논문집 Vol.28 No.2

본 연구는 고층건축물의 기본설계 단계에서 평면형태를 결정할 때, 응용할 수 있도록 다양한 형상을 가진 고층건축물에 작용하는 풍력 및 풍응답에 대한 데이터베이스를 구축하는데 목적이 있다. 따라서 본 논문에서는 풍력데이터베이스의 초기단계로, 높이 200m이상의 고층건축물의 변장비(D/B=0.33, 0.50, 0.77, 0.83, 0.91, 1.0, 1.1, 1.2, 1.3, 2.0, 3.0) 변화에 따른 풍력의 특성을 조사하고 기존 문헌과의 비교 검토를 통해 실험결과를 검증하였다. 또한 풍하중조합의 관점에서 풍방향-풍직각방향, 풍방향-비틀림방향 및 풍직각방향-비틀림방향 간의 풍력의 상호상관에 대해서 검토하였다. 실험결과, 풍방향 및 풍직각방향에 대한 평균 및 변동 모멘트계수와 풍직각방향 및 비틀림방향 변동모멘트계수의 파워스펙트럼밀도의 결과는 기존 연구결과와 잘 부합되는 것으로 나타났다. 또한, 지표면조도의 변화에 따른 풍방향, 풍직각방향 및 비틀림방향에 대한 풍력의 특성은 큰 변화가 없는 것으로 나타났다. 시간영역과 주파수영역에서의 변동모멘트의 상호상관계수 분석결과, 풍직각방향-비틀림방향 변동모멘트계수의 상호상관계수가 높게 나타나는 경향을 보였다. The objective of this study is to construct the TPU aerodynamic database with wind tunnel test data of overall wind loads and responses on tall buildings. In this study, wind tunnel tests were conducted to investigate characteristics of wind forces and the effect of wind load combination by cross-correlation analysis among along-wind overturning moment, across-wind overturning moment and torsional moment on a tall building with various side ratios(D/B=0.33, 0.50, 0.77, 0.83, 0.91, 1.0, 1.1, 1.2, 1.3, 2.0 and 3.0) for different terrain roughnesses. The results of wind tunnel tests were compared with those of past literatures. As a result, there was no significant effects of changing of terrain roughnesses on moment coefficients and power spectral densities of across-wind overturning moment coefficients and torsional moment coefficients with various side ratios. Further, these results were good agreement with those of past literatures. From cross-correlation analysis, the across-wind overturning moment coefficients were highly correlated with the torsional moment coefficients. The results of this study will be helpful for practical designers in preliminary design stage.