Extreme wind load estimates based on the Gumbel distribution of dynamic pressures: an assessment

Abstract

We present a contribution to the current debate on whether it is more appropriate to fit a Gumbel distribution to the time series of the extreme dynamic pressures (i.e. of the squares of the extreme wind speeds) than to fit an extreme value distribution to the time series of the extreme wind speeds themselves. It has been shown that the use of time series of the extreme dynamic pressures would be justified if the time series of the wind speed data taken at small intervals (e.g. 1 h) were, at least approximately, Rayleigh-distributed. We show that, according to sets of data we believe are typical, this is not the case. In addition, we show results of probability plot correlation coefficient (PPCC) analyses of 100 records of sample size 23 to 54, according to which the fit of reverse Weibull distributions to largest yearly wind speeds is considerably better than the fit of Gumbel distributions to the corresponding largest yearly dynamic pressures. We interpret the data and results presented in the paper as indicating that there is no convincing support to date for the hypothesis that the Gumbel distribution should be used as a model of extreme dynamic pressures.