Wind Field Coherence And Dynamic Wind Forces
Dynamic response of structures to turbulent wind depends on the temporal and spatial fluctuations of the wind. In principle the statistical properties could be combined into a random field model of the turbulent wind. However, in practice it turns out to be very difficult to combine the height variation of the mean wind with a fully satisfactory stochastic description of the turbulent fluctuations. Several models have been proposed, but none of them combine completeness and simplicity, and we shall restrict the attention to some basic characteristics. The combination of spatial and temporal fluctuations is made by Taylor’s hypothesis of convected frozen turbulence. This amounts to convecting a time-invariant velocity field downstream with the mean velocity. Within this approximation the problem is reduced to a stochastic spatial wind velocity field. The classical account of the theory for homogeneous isotropic turbulence is Batchelor (1953). Several extensions to anisotropic turbulence have been proposed. The most promising is probably that of Mann (1994), in which the effect of shear due to the vertical gradient of the mean wind is accounted for as a perturbation in the Navier-Stokes equations. This model accounts for differences in the three velocity components and is easily adapted to simulation, Mann fc Krenk (1993).
KeywordsExponential Format Coherence Function Wind Force Convect Turbulence Homogeneous Isotropic Turbulence
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- Davenport, A.G. (1977) The prediction of the response of structures to gusty wind, in Safety of Structures under Dynamic Loading, Holand, Kavlie, Moe and Sigbjôrnsson (eds.), pp. 257–284. Tapir, Trondheim.Google Scholar
- Eurocode (1994) Eurocode 1: Basis of Design and Actions on Structures, Part 2–4: Wind Actions, CEN, European Committee for Standardization, Brussels.Google Scholar
- Harris, R.I. (1970) The nature of the wind, in Seminar on Modern Design of Wind- Sensitive Structures, 1970, pp. 29–55. Construction Industry Research and Information Association, CIRIA, London.Google Scholar
- Mann, J. and Krenk, S. (1994) Fourier simulation of a non-isotropic wind field model, in Structural Safety and Reliability, Schueller, Shinozuka and Yao (eds.), pp. 1669–1674. Balkema, Rotterdam.Google Scholar
- Simiu, E and Scanlan, R.H. (1986) Wind Effects on Structures, Second Edition. Wiley, New York.Google Scholar