## 1 Introduction  
There are several cases [1, 2, 3, 4] of cooling tower damage caused by wind, suggesting that their structural design needs greater emphasis on the temporal-spatial distribution of wind loads. With the implementation of the \"Turn on the big generator set and shut down the small generator set\" policy of the Chinese thermal power industry, the trend of new cooling towers becoming bigger and bigger has made them more sensitive to wind. Significantly, the structural characteristics of tall and thin shells increase the wind damage problem [5], especially in southeastern coastal areas of China where typhoons are frequent. China's current wind resistance design codes [6] for cooling towers are based on the normal wind. Typhoons involve strong wind field energy, high-shear wind speeds, and complex near-surface wind profiles [7]. If these are not fully considered, the aerodynamic and structural stability of existing cooling tower systems may be potentially unsafe; therefore, it is necessary to study the mechanisms of super-large cooling tower collapse due to typhoons. Existing research [8, 9, 10] on the typhoon resistance of buildings is mostly based on limited measured data. The typhoon engineering models commonly used in structural wind engineering are somewhat simplified and have difficulty in truly reflecting the typhoon wind field characteristics of strong wind field energy, high shear wind speeds, and disordered wind fields. Due to the huge range of typhoons, its minimum simulation mesh size is in the order of kilometers. The Weather Research and Forecasting model (WRF) is the most widely used typhoon research and forecasting technology. However, the overall size of large-scale cooling towers is only of the order of 100 m, and to accurately predict vortex shedding of the structure's surface it is also necessary to strictly limit the boundary layer mesh size to the order of centimeters. In this mesh scale requirements, the WRF will completely fail, but the Computational Fluid Dynamics (CFD) model is appropriate for simulating small-scale structures, airflow, and air pressure fluctuations. Therefore, this paper intends to use a WRF-CFD wind field downscaling technology [11; 12] to achieve typhoon-scale near-ground wind field simulations and solve the multi-scale transfer problem of flow structures. Surveys of wind damage to large cooling towers [1; 2; 3; 4] show that the wind-induced collapse of cooling towers is mainly due to excessive local wind loads. These result in partial tensile failure of the tower, which causes further structural damage and buckling instability. This kind of wind damage caused by accidental loads is a typical form of continuous collapse [13]. Foreign design guides [14; 15] and the Chinese code [16] provide a specific anti-continuous collapse design method. However, their main aim is the seismic design of RC frame structures and there is a lack of anti-collapse regulations for tall and thin shell structures. Studies [17; 18; 19; 20] show that the main evaluation indices of wind-induced collapse in large-scale cooling towers are buckling instability, strength failure, and fatigue damage. Current research on wind stability of large-scale cooling towers has mainly focused on static wind instability [21], global and local buckling instability [22], stability throughout the construction process [23], and instability due to geometrical defects [24]. The results have guided the wind-resistant design of super-large cooling towers and have a certain significance for understanding their collapse processes. However, the follow-up phenomena of the continuous collapse caused by local instability are ignored and it is difficult to determine the wind-induced collapse process of such super-large cooling towers and its internal force mechanism. Therefore, a medium-scale WRF model is introduced to perform a fine simulation of the tower near-surface wind field of the strongest typhoon (Super Typhoon \"Rammasun\") that has occurred in China since 1949.