Toward the Codification of Thunderstorm/Downburst Winds

Non-synoptic winds often exhibit rapid changes during a short period, which may be accompanied by changes in direction. This introduces non-stationarity both in the mean and the standard deviation of wind fluctuations. Thus, design loads in non-synoptic non-stationary winds obtained from conventional analysis frameworks included in codes and standards, such as the gust loading factor approach, may not be appropriate, thus calling for a careful examination of traditional design procedures. This chapter reviews a proposed design procedure for non-synoptic non-stationary winds. In particular, a codification of gust front winds originating from thunderstorms and downbursts is discussed because the event occurs frequently and is well-known to exhibit significant non-stationary characteristics. Two major frameworks reported in the past literature, such as the gust front factor and the thunderstorm response spectrum technique, are examined as a step toward the codification of gust front winds. In addition, a comparison is made between the two frameworks to assess their performance. Finally, a living codification concept through learning and updating invoking the emerging “design thinking” approach is discussed.