Kexin Guo

Understanding the characteristics of downburst wind fields is crucial for studying structural resistance to downbursts. Based on measured data from the 325 m meteorological tower in Beijing, this paper investigates the spatiotemporal evolution of mean and fluctuating winds during a non-stationary downburst. Key wind field parameters such as the mean wind speed, turbulence intensity, turbulence integral length scale, probability density function, power spectral density, evolutionary power spectral density, and gust factor are statistically analyzed. The results show that the wind speed of downburst undergoes rapid changes, with wind direction significantly influenced by outflow vortices at low altitudes and relatively stable at higher altitudes. When the event happens, the temperature decreases sharply. The mean wind speeds and turbulence integral length scale of the downburst exhibit pronounced “nose-shaped” profile characteristics at the moment when peak wind speed occurs. The turbulence intensity at lower altitudes predominantly exceeds that at higher altitudes. The probability density distribution function of the reduced fluctuating wind speed matches the standard Gaussian distribution curve. The fluctuating wind speeds of the downburst exhibit significant non-stationary characteristics, with their energy mainly distributing in the period of rapid change of wind speed in the time domain and concentrating in the vicinity of 0–0.1 Hz in the frequency domain. The gust factor reaches its maximum at the moment when the peak wind speed occurs.

Downbursts belong to sudden, local, and strong convection weather, which present significant destruction for structures. At any given time, there are approximately 2000 thunderstorms occurring on the Earth. Many studies have investigated the effects of downbursts on different structures. However, the extensive range of varying wind field parameters and the diverse representations of wind speeds render the study of structural wind effects complex and challenging under downbursts. This study firstly reviews the research of wind field properties of downbursts according to four common approaches, and the major findings, advantages, and disadvantages of which are concluded. Then, failure analysis of transmission line systems under stationary and moving downbursts is explored. The article also reviews the wind pressure on the roof of different kinds of low-rise buildings, and some dominant parameters, namely roof slope, distance of building from downburst center, wind direction angle, and so on, are discussed. Moreover, the wind effects caused by downbursts on high-rise buildings and some specialized structures are also considered because more and more wind hazards are related to downbursts. Finally, the limitations of the current study are pointed out, and recommendations for further research are given for the accurate assessment of the effects of wind on buildings, with a view to providing safer and more economical wind-resistant design solutions for structures.