On the probabilistic representation of the wind climate for calibration of structural design standards

The article presents a contribution to the current debate on the probabilistic representation of the wind speed extremes for calibration of the partial safety factor covering wind action. The requirements for the probabilistic model are formulated. The Gumbel distribution is shown to represents best the 10-min mean wind velocity yearly maxima based on theoretical considerations and analyses of real data with different statistical techniques. Data from locations across a large geographical region indicate that the coefficient of variation of the distribution varies over the territory. A method is proposed for accounting this variation in order to calibrate a single partial safety factor for the whole territory. The distribution location is indirectly given in design standards through the georeferenced characteristic wind speed values. A solution for including the uncertainty affecting these values is suggested. The findings are implemented in an illustrative calibration exercise. The proposed methods and concepts might be applied to other environmental actions such as the snow loads.