Wind tunnel investigation of correlation and coherence of wind loading on generic tall twin buildings in close proximity

Lim, Juntack,Bienkiewicz, Bogusz Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.4

A popular modern architectural form for tall buildings is two (or more) towers which are structurally linked through such features as a shared podium or sky-bridges. The fundamental features of the wind loading and the structural links of such buildings can be studied by measuring load components on the individual unlinked towers along with their correlations. This paper describes application of dual high frequency force balance (DHFFB) in a wind tunnel study of the base wind loading exerted on generic tall twin buildings in close proximity. Light models of two identical generic tall buildings of square plan were mounted on DHFFB and the base wind loading exerted on the buildings was simultaneously acquired. The effects of the relative positions of the buildings on the correlations and coherences involving loading components on each building and on the two buildings were investigated. For some relative positions, the effects of the building proximity on the wind loading were significant and the loading was markedly different from that exerted on single buildings. In addition, the correlations between the loadings on the two buildings were high. These effects have potential to significantly impact, for example, the modally-coupled resonant responses of the buildings to the aerodynamic excitations. The presented results were not meant to be recommended for direct application in wind resistant design of tall twin buildings. They were intended to show that wind loading on tall buildings in close proximity is significantly different from that on single buildings and that it can be conveniently mapped using DHFFB.

Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

임준택 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual-HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

Lim Juntack 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

스카이브릿지로 연결된 쌍둥이 초고층건물은 두 가지 종류의 연동성-스카이브릿지로 인해 두 건물의 거동 동기화를 유발하는 구조적 연동성과 작용하는 풍하중의 높은 상관성으로 인한 공기역학적 연동성-이 나타난다. 단일 건물에 널리 적용되는 전통적인 풍력실험 방법으로는 이런 연동성과 영향들을 완벽히 파악할 수 없는 실정이다. 그런 이유로 보다 발전된 동적 풍응답 해석법이 요구된다. 이 논문은 스카이브릿지로 연결된 쌍둥이 건물에서 발생하는 구조적 및 공기역학적인 연동성을 다룰 수 있는 듀얼 풍력실험 방법을 자세히 다루었다. 제안된 방법을 적용하여 건물의 풍가속도에 대한 구조적 및 공기역학적 연동성의 영향을 평가하였다. 건물의 풍응답 산정에 스펙트럼 적분법과 백색 소음 근사법을 적용하였다. 실험 및 결과로 볼 때 동적 풍응답에 상당한 영향이 있음을 확인할 수 있었다. 여러 개의 풍력 측정센서를 활용한 풍력실험 기술은 구조적으로 연결된 초고층건물에 대한 풍동실험에 유용하게 사용될 것으로 판단된다. Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual- HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

Wind-induced response of structurally coupled twin tall buildings

Lim, Juntack,Bienkiewicz, Bogusz Techno-Press 2007 Wind and Structures, An International Journal (WAS Vol.10 No.4

The paper describes a study of the effects of structural coupling on the wind-induced response of twin tall buildings connected by a skybridge. Development of a dual high-frequency force balance used in wind tunnel investigation and background information on the methodology employed in analysis are presented. Comparisons of the wind-induced building response (rooftop acceleration) of structurally coupled and uncoupled twin buildings are provided and the influence of structural coupling is assessed. It is found that the adverse aerodynamic interference effects caused by close proximity of the buildings can be significantly reduced by the coupling. Neglecting of such interactions may lead to excessively conservative estimates of the wind-induced response of the buildings. The presented findings suggest that structural coupling should be included in wind-resistant design of twin tall buildings.

트윈 빌딩의 공력 특성이 풍응답에 미치는 영향 평가

김법렬 한국전산구조공학회 2020 한국전산구조공학회논문집 Vol.33 No.1

The wind responses of twin buildings are determined by the characteristics of wind loads and the dynamic characteristics of the structural systems of the buildings. In this study, the characteristics of wind pressure that influence wind responses were identified for two different spacings between the twin buildings using a wind tunnel test and the proper orthogonal decomposition (POD) method. Structural dynamic characteristics were also identified using 3D structural system modeling. The double modal transformation method was utilized to evaluate the characteristics of wind pressure for across-wind and along-wind conditions and the effect of the dynamic characteristics of each structure on the wind responses . The channeling and vortex effects were identified through the POD method. Across-wind loads were significantly affected by the spacings between the twin buildings, whereas along-wind loads were minimally affected. Similarly, while using the double modal transformation method, a significant difference was noticed in case of the cross-participation coefficients in the across-wind direction condition for the different spacings between the buildings; however, the along-wind direction condition showed negligible difference. Therefore, the spacing between the two buildings plays a more important role in across-wind responses compared to along-wind responses. 트윈 빌딩의 풍응답은 풍하중의 공력 특성과 트윈 빌딩 구조 시스템의 동적 특성에 영향을 받는다. 본 논문에서는 트윈 빌딩의 두 빌딩의 간격이 다른 두 경우에 대해서 풍응답에 영향을 주는 풍압의 특성을 풍동 실험과 적합 직교 분해 기법을 이용해 파악하고, 3차원 구조 시스템 모델링을 통해 동특성을 파악하였다. 그리고 이중 모달 변환 기법을 이용해서 각 풍압의 특성과 구조물의 동특성이 풍응답에 미치는 영향을 파악하였다. 적합 직교 분해 기법을 통해서 채널링과 와류 효과에 대해서 파악할 수 있었다. 풍 직각 뱡향의 풍하중은 두 빌딩의 간격에 영향을 많이 받았으며, 풍 방향의 풍하중은 간격에 영향을 적게 받았다. 마찬가지로, 이중 모달 변환 기법에서 교차 참여 계수는 풍 직각 방향에서는 두 빌딩의 간격에 따라 크게 달라진 반면, 풍 방향은 영향이 적었다. 이에 따라 두 빌딩의 간격이 풍 방향의 풍응답 보다 풍 직각 뱡향의 풍응답에 중요한 역할을 하는 것을 알 수 있었다.

트윈 빌딩의 적합 직교 분해 기법을 이용한 풍하중 및 풍응답 평가

김법렬 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.6

트윈 빌딩의 풍하중의 특성과 구조적 특성은 일반 고층건물보다 복잡하다. 이러한 특성을 조사하기 위해서 풍동실험을 통해서 트윈 빌딩의 풍압을 계측하였다. 계측된 데이터와 적합 직교 분해 기법을 이용하여 풍압의 패턴을 파악하였다. 1차 모드에서는 채널링 효과가 2차 모드에서는 와류 효과가 나타났다. 또한, 두 빌딩의 하중의 상관관계를 파악하였는데, 풍 방향 하중은 양의 상관관계를 가지며, 풍 직각 방향의 하중은 명확한 상관관계가 나타나지 않았다. 이러한 상관관계는 횡 방향 변위에도 영향을 미쳤다. 양의 상관관계를 가지면 트윈 빌딩을 연결하는 구조부재의 영향이 적게 작용한 반면에 음의 상관관계를 가지면 연결 구조부재의 영향이 횡 방향의 변위를 줄이는데 큰 영향을 미치게 되었다. The wind load and structural characteristics of a twin building are more complex than those of conventional high-rise buildings. The pressure load due to wind on a twin building was therefore measured via wind tunnel experiments to analyze such characteristics. The wind pressure pattern was then deduced from measured data using proper orthogonal decomposition. Channeling and vortex shedding were observed in the first and second modes, respectively. The along-wind loads on the two buildings featured a positive correlation and the cross-wind loads featured no correlation. Such a correlation affected the wind-induced displacement. The structural member connecting the two buildings had an insignificant effect on the positive correlation, but it notably reduced the wind-induced displacement with a negative correlation.