Statistical analysis of low-occurrence strong wind speeds at the pedestrian level around a simplified building based on the Weibull distribution

In this study, low-occurrence strong wind speeds (LOSWSs) at the pedestrian level around a high-rise building were statistically analyzed based on the two-parameter (2W) and three-parameter (3W) Weibull distributions. A wind speed database obtained using large-eddy simulations was used. The cumulative distribution functions of the wind speeds were well fitted by 2W and 3W in most regions. In the recirculation region next to the side wall of the building, the goodness of fit of 2W and 3W was slightly worse than that in other regions owing to the bimodal distribution. Compared with 2W, the location parameter of 3W improved the fit in a relatively far range beside the building. From the distribution of the scale parameter of 3W, the separation region was found to have a wider distribution range of wind speeds than other regions. Methods for estimating LOSWSs based on statistics were also discussed. Based on the Weibull distribution, the theoretical peak factors can be estimated from the coefficient of variation (CV) (2W method) or skewness (3W method) of the wind speeds. Both methods demonstrated high accuracies for estimating the LOSWSs with exceedance probabilities q = 30%–0.1%. The relative errors were within 10% at most points for both methods. However, the 3W method was more accurate than the 2W method for q = 1% and 0.1% because skewness is a higher-order statistic than CV, which results in a closer relationship with low-occurrence values.