역추정된 풍직각방향 모달하중에 기초한 원형 실린더 구조물의 공력감쇠비 산정
Estimation of Aerodynamic Damping Ratio of Circular Cylinder Structure Based on Inversely Identified Across Modal Wind Load
1
조회
0
다운로드
3
인용
0
참고문헌
키워드
초록
공력감쇠는 와류에 의한 풍직각방향의 응답을 평가하는데 매우 유용한 인자로 인식되어 왔다. 그러나 기존의 공력감쇠 산정방식은 구조물 응답에 기반한 시스템 식별기술을 적용하는 것으로 와류하중속에 포함되어 있는 공력감쇠의 역할과 특성을 파악하는데 한계를 가지고 있었다. 본 연구에서는 하중식별기술을 적용하여 와류하중을 직접적으로 구함으로써 와류하중을 구성하는 요소와유발요인을 평가하고자 하였다. 이를 위하여 대기 경계층에서 원형 실린더 모델에 대한 공탄성 실험을 수행하여 풍직각방향 와류하중을 추정하였으며 그로부터 공력감쇠의 특성을 분석하였다. 분석결과, 와류하중은 구조물 모달속도가 공력감쇠에 의해 풍하중으로 전환되는 모달속도하중과 변동풍속에 의해 형성되는 순수 와류하중으로 구성되는 것으로 나타났다. 공력감쇠는 최상층 평균풍속에 의한와류방출진동수가 구조물의 고유진동수에 근접하면서 부감쇠를 가지며 그 결과 총 감쇠가 작아져 응답증폭현상을 유발하는 것으로 파악되었다. 본 연구결과에 기초하면, 난류상태에서 와류하중 특성이 반영된 와류하중모델 구축이 가능할 것으로 사료되며, 구조물 풍직각방향 진동을 보다 효과적으로 파악하는데 활용될 수 있을 것으로 사료된다.
Abstract
Aerodynamic damping has been recognized as one of the most useful factors to evaluate the vortex induced vibration of a slender structure. However, conventional estimation methods of the aerodynamic damping have been mainly based on the system identification technology in associated with the structural responses, so that these have some limitations in directly understanding the role and characteristics of aerodynamic damping inherent in the vortex induced load. In this study, by directly identifying vortex induced load with force identification method, the components and the causative factors of vortex induced load are evaluated. For this purpose, the aeroelastic model test for circular section was performed in the boundary layered wind tunnel, and then the vortex induced load and the aerodynamic damping ratio are subsequently identified. From the analysis study, it is found that the vortex induced load is composed of the modal velocity induced load, where the modal velocity of the structure is converted to wind load by aerodynamic damping, and the pure vortex induced load formed by the instantaneous across wind velocity. The aerodynamic damping is changed into negative damping when vortex induced frequency is approaching to the natural frequency of the aeroelastic model, and resulting in the vortex induced resonance due to the decrease in total damping. Based on the results, the mathematical model for vortex induced load can be constructed in the turbulent wind, and it can be used to more effectively understand the across-wind response of high-rise building.
참고문헌 (23)
- Holmes, J. D, "Along-wind response of lattice towers-II. Aerodynamic damping and deflections", Engineering Structures, 18(7), pp.483~488 (1996)
- Gabbai, R.D, "Aerodynamic damping in the along-wind response of tall buildings", Journal of Structural Engineering, 136(1), pp.117~119 (2010)
- Simiu, E, "Wind effects on structures - 3rd edition" (1996), John Wiley & Sons, Inc
- Dowel, E. H, "A modern course in aeroelasticity-forth revised and enlarged edition" (2004), Kluwer academic Publishers
- Vickery, B. J, "Across-Wind vibrations of Structures of Circular Cross-Section. Part I. Development of a Two-Dimensional Model for Two-Dimensional Conditions", Journal wind engineering and industrila aerodynamics, 12, pp.49~73 (1983)
- Basu, R. I, "Across-Wind vibrations of Structures of Circular Cross-Section. Part II. Development of a full scale application", Journal wind engineering and industrial aerodynamics, 12, pp.75~97 (1983)
- Hayashida, H, "Aerodynamic damping effects of tall building for a vortex induced vibration", Journal wind engineering and industrial aerodynamics, 43(1-3), pp.1973~1983 (1992)
- Marukawa, H, "Experimental evaluation of aerodynamic damping of tall buildings", Journal wind engineering and industrial aerodynamics, 59(2-3), pp.177~190 (1996)
- Watanabe, Y, "Empirical aerodynamic damping function for tall buildings", Journal wind engineering and industrial aerodynamics, 72(1-3), pp.313~321 (1997)
- Yong Quan, "Experimental evaluation of aerodynamic damping of square super high-rise buildings", Wind and Structures, An International Journal, 8(5), pp.309~324 (2005), 한국풍공학회
- Huang, P, "Experimental study of aerodynamic damping of typical tall building", Mathematical Problems in Engineering, 2013, pp.1~9 (2013)
- Wang, L, "Investigation on the unstability of vortex induced resonance of high-rise buildings", Journal wind engineering and industrial aerodynamics, 175, pp.17~31 (2018)
- Wang, L, "Improved expression for across-wind aerodynamic damping ratios of super high-rise building", Journal wind engineering and industrial aerodynamics, 176, pp.263~272 (2018)
- Sanchez, J, "Review of force reconstruction techniques", Journal of Sound and Vibration, 333, pp.2999~3018 (2014)
- Gillijns, S, "Unbiased minimum-variance input and state estimation for linear discrete-time systems", Automatic, 43, pp.111~116 (2007)
- 황재승, "건물의 가속도를 이용한 풍하중 산정기법", 한국풍공학회지, 9(2), pp.197~207 (2005), 한국풍공학회
- Hwang, J. S, "Estimation of modal loads using structural response", Journal of Sound and Vibration, 326, pp.522~539 (2009)
- Hwang, J. S, "Wind load identification using wind tunnel test data by inverse analysis", Journal of Wind Engineering and Industrial Aerodynamics, 99, pp.18~26 (2011)
- Holmes, J. D, "Wind Loading of Structure" (2001), Spon Press
- 황재승, "하중추정기법에 의한 원형 실린더 구조물의 와류하중추정", 한국풍공학회지, 21(4), pp.203~209 (2017), 한국풍공학회
- Hwang, J. S, "Equivalent damping of a structure with vibration control devices subjected to wind loads", Wind and Structures, 6(4), pp.249~262 (2003)
- Lee, S. H, "Estimation of equivalent damping ratio of a structure with added dampers", Engineering Structures, 26, pp.335~346 (2004)
- Hwang, J.-S, "Estimation of structural modal parameters under winds using a virtual dynamic shaker", Journal of Engineering Mechanics, 144, pp.04018007~ (2018)