Influence of wind directionality on wind loads and responses

Different methods of allowing for wind directionality are discussed and their effects on predicted structural wind loads and responses of buildings and cladding pressures are examined. Results are presented for several tall buildings, for which wind tunnel model tests have been made, as well as for hypothetical buildings with generic aerodynamic signatures. Predictions of extreme wind loads and responses are made in both extra-tropical and tropical wind climates. Three of the analysis methods, namely the worst-case approach, the sector-by-sector method, and the up-crossings method are probabilistic procedures which rely on historical wind records. Also discussed is a time-domain analysis which tracks wind loads and responses during the passage of particular storms. This requires time histories of wind speed and direction that at this time are only available for tropical storms, where Monte Carlo simulations are used to determine time histories of the wind field. Directional factors are extracted from all predictions made in this study. These factors provide direct comparisons of extremes wind loads and effects predicted with particular methods of analysis to the corresponding predictions made with the worst-case method, which does not recognize the azimuthal variation of the aerodynamic data or the directional preferences of severe winds.