Carassale, L. & Longo, R. (2010).

Abstract
The aerodynamic action on rigid structures is traditionally classified assigning his origin to the turbulence field present in the incident flow or to the fluctuations of the pressure field around the body due to the wake. In both cases, it is known that the structures size influences in some way the characteristics of the global forces because of the partial spatial correlation existing in the wind field or in the structure of the vortexes. The size of the body invested by the wind has two further important effects regarding the probabilistic representation of the actions. One of these can be clearly seen when a modal expansion of the aerodynamic loads is applied (Carassale et al., 2007) and, as usually happen, the minimum number of modes needed to represent the wind force with an assigned accuracy tends to grows when the structure dimension increases. The second effect involves the probabilistic distribution of the global forces acting on the structure. The aim of this paper is to comprehend the importance of the scale effects described above and their implications on the dynamic response of a linear structure exposed to a turbulent wind.