Neutral and non-neutral atmosphere: Probabilistic characterization and wind-induced response of structures

Atmospheric conditions vary on the basis of the local thermal stratification, giving rise to stable, unstable or neutral atmospheric conditions, that can modify the incoming wind field and the consequent structural loads and response. This paper studies the problem from two points of view. Starting from a large database of in situ measurements of thermal stratification parameters, the first part of the paper proposes an analytical model for the statistical distribution of atmospheric conditions on varying the mean wind velocity. This model is then adopted, in the second part of the paper, to analyze the vortex-shedding response of chimneys, highlighting the great variability of the maximum response under thermal atmospheric conditions with the same probability of occurrence.