• Wind and Structures
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• 제18권4호
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• pp.375-389
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• 2014

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

• 한국수자원학회논문집
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• 제45권5호
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• pp.455-464
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• 2012

이 논문에서는 관망시스템의 수격압 현상을 모의하기 위해서 합성 부정류 마찰 모형을 개발하였다. 부정류 마찰항을 고려하기 위한 방법으로 빈도 의존 마찰항과 순간 가속도 기반 마찰 모형을 합성하였으며, 특성선 방법을 모형 개발의 기반으로하였다. 관망에서의 부정류 모형으로 가장 널리 쓰이는 Zielke의 마찰항 모형과 Ramos의 마찰항 모형들과 종합적인 비교를 수행하였다. 모의 결과를 검증하기 위해서 고빈도로 수압을 측정할 수 있는 자료 획득체제를 구비한 관망시스템을 구축하였다. 정상상태에서 밸브 급폐로 야기된 수격압의 수압 시계열을 2가지 Reynolds수에서 확보하였다. 모의결과는 pilot 관망체제에서 확보한 실험 자료와 비교하였다. 부정류 마찰항 모형의 매개변수 보정을 위해서 시행착오 방법이 도입되었으며, 부정류 마찰항들을 비교한 결과는 수격압에서 수압이 감쇄되는 과정에 대한 전반적인 이해를 돕고자 하였다. 이와 같은 결과는 관망의 천이류를 적절히 예측하는데 부정류 마찰항의 적절한 고려가 필수적인 부분임을 알려 주고 있다.

• Wind and Structures
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• 제18권5호
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• pp.567-598
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• 2014

In this paper, wind induced aerodynamic loads on a standard tall building have been evaluated through large-eddy simulation (LES) technique. The flow parameters of an open terrain were recorded from the downstream of an empty boundary layer wind tunnel (BLWT) and used to prescribe the transient inlet boundary of the LES simulations. Three different numerically generated inflow boundary conditions have been investigated to assess their suitability for LES. A high frequency pressure integration (HFPI) approach has been employed to obtain the wind load. A total of 280 pressure monitoring points have been systematically distributed on the surfaces of the LES model building. Similar BLWT experiments were also done to validate the numerical results. In addition, the effects of adjacent buildings were studied. Among the three wind field generation methods (synthetic, Simirnov's, and Lund's recycling method), LES with perturbation from the synthetic random flow approach showed better agreement with the BLWT data. In general, LES predicted peak wind loads comparable with the BLWT data, with a maximum difference of 15% and an average difference of 5%, for an isolated building case and however higher estimation errors were observed for cases where adjacent buildings were placed in the vicinity of the study building.