Imprecise model of thunderstorm wind speed and uncertainty propagation on the maximum dynamic response

The wind velocity field associated with thunderstorm downbursts can be modelled as a uniformly modulated nonstationary random process, characterized by an Evolutionary Power Spectral Density function. The parameters characterizing the evolutionary model vary significantly from one thunderstorm to another. Due to the limited data availability, the interval model appears to be a suitable approach to represent the uncertainty of such parameters. In this paper, by leveraging available thunderstorm data and a literature-based model for the vertical profile of mean velocity, appropriate bounds for the key loading parameters are established, and an interval model for the thunderstorm wind speed is introduced. Employing a closed-form solution for the gust response factor and based on the introduced interval model of the thunderstorm wind speed, this study investigates the propagation of uncertainties on the thunderstorm gust response factor and the maximum dynamic response for slender vertical structures using the Improved Interval Analysis. Results indicate that, for the structural cases analyzed, uncertainties in thunderstorm parameters exert a more significant influence on the thunderstorm gust response factor and maximum response than those in the structural parameters.