Random Lock-In Intervals for Tubular Structural Elements Subject to Simulated Natural Wind
Publication: Journal of Engineering Mechanics
Volume 125, Issue 12
Abstract
This paper reports on wind tunnel experiments with an elastically suspended circular cylinder vibrating under the excitation of natural wind of high turbulence degree. The natural wind turbulence was simulated by superposing the low frequency part of the natural wind turbulence on the background high frequency turbulence of the wind tunnel flow. This was done by controlling the propeller rotation speed according to an artificially generated low frequency speed sample function drawn from a suitable random process model. The experiment provided statistical data on the intermittent random occurrence and size of strong lock-in vibrations in resonance with the vortex shedding excitation. The purpose of the experiment was to obtain data to support the formulation of a sufficiently detailed stochastic model to allow computer simulation of reasonably realistic fatigue damage accumulation at “hot spots” of tubular structural elements subject to the natural wind. The engineering relevance of the investigation is supported by comparing it with the unrealistic highly conservative rules of wind-induced fatigue commonly given in codes of practice. The stochastic lock-in model as well as the related fatigue calculation procedure is reported in the paper.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Bishop, R. E., and Hassan, A. T. (1964). “The lift and drag forces on an oscillating cylinder.” Proc., Royal Soc. London, Series A, 277, 51–75.
2.
Brika, D., and Laneville, A. (1993). “Vortex-induced vibrations of long flexible circular cylinder.” J. Fluid Mech., Cambridge, U.K., 250, 481–508.
3.
Christensen, C. F. ( 1997). “Stochastic oscillations induced by vortex shedding in wind,” PhD thesis, Series R, No. 23, Dept. of Struct. Engrg. and Mat., Technical University of Denmark, Lyngby, Denmark.
4.
Ditlevsen, O. (1985). “Fatigue model for elastic bars in turbulent wind.” J. Wind Engrg. and Industrial Aerodynamics, 18, 27–52.
5.
Feng, C. C. ( 1968). “The measurement of vortex-induced effects in a flow past stationary and oscillatory circular and d-section cylinders,” Master's thesis, University of British Columbia, Vancouver.
6.
Ferguson, N. ( 1965). “The measurement of wake and surface effects in the subcritical flow past a circular cylinder at rest and in vortex-excited oscillation,” Master's thesis, Univ. of British Columbia, Vancouver, British Columbia, Canada.
7.
Goswami, I., Scanlan, R. H., and Jones, N. P. (1993). “Vortex-induced vibration of circular cylinders. I: Experimental data.”J. Engrg. Mech., ASCE, 119, 2270–2287.
8.
Heine, W. ( 1964). “On the experimental investigation of vortex excited pressure fluctuations,” Master's thesis, Univ. of British Columbia, Vancouver, British Columbia, Canada.
9.
Koopmann, G. H. (1967). “The vortex wakes of vibrating cylinders at low Reynolds numbers.” J. Fluid Mech., 28, 501–512.
10.
Öngören, A., and Rockwell, D. (1988). “Flow structure from an oscillating cylinder: Part 1 and 2.” J. Fluid Mech., 191, 197–245.
11.
Sarpkaya, T. (1979). “Vortex-induced oscillations. A selective review.” J. Appl. Mech., 46, 241–258.
12.
Simiu, E., and Scanlan, R. H. (1996). Wind effects on structures, 3rd Ed., Wiley, New York.
13.
Williamson, C. H. K., and Roshko, A. ( 1988). “Vortex formation in the wake of an oscillating cylinder.” J. Fluids Struct., 2, 355–381.
Information & Authors
Information
Published In
History
Received: Jul 1, 1997
Published online: Dec 1, 1999
Published in print: Dec 1999
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.