Equivalent Wind Spectrum Technique: Theory and Applications

Abstract

The equivalent wind spectrum technique is a mathematical model according to which wind is schematized as a stochastic stationary Gaussian process made up of a mean‐speed profile on which an equivalent turbulent fluctuation, perfectly coherent in space, is super‐imposed. The equivalent criterion is formulated by defining a fictitious velocity fluctuation, random function of time only, giving rise to power spectra of fluctuating modal force that approximate, optimally, the corresponding modal spectra related to the actual turbulence configuration. This paper presents the basic assumptions and the theoretical steps leading to the characterization of the equivalent velocity fluctuation through a power spectrum assigned in closed form. The method proposed herein allows one to estimate the dynamic along‐wind response of structures, both in frequency and in time domain, with a high level of precision and simplicity; furthermore it makes it possible to treat wind effects, as well as those of earthquakes, through the well‐known response spectrum technique.