# Study on Fluctuating Wind Characteristics and Non-Stationarity at U-Shaped Canyon Bridge Site
## 5 Conclusions  
This study examines the pulsating wind characteristics at the U-shaped canyon bridge site in Yunnan Province, introduces non-stationary theory and associated analysis methods, and analyzes the pulsating wind from various perspectives. These include the differences in pulsating wind characteristics caused by different models, the stationarity test at various heights, and research on the optimal decomposition level for DWT. The conclusions are as follows:  
1. Wind speed in the canyon area exhibits bimodal distribution characteristics, and the Weibull-Gamma mixed distribution model achieves the best fit, with R\({}^{2}\) = 0.998.  
Figure 16: PSD analysis comparing original and reconstructed fluctuating wind.  
2. Under the stationary hypothesis, the turbulence intensity is mainly distributed in the range of 0.05-0.30 and decreases with the increase in wind speed. The gust factor is mainly distributed in the range of 1.0-2.0, and has a strong linear correlation with turbulence intensity (R\({}^{2}\) = 0.85).
3. Stationarity analysis reveals that the proportion of non-stationary sequences in mountainous areas increases with height. Wavelet decomposition shows that all pulsating wind samples reconstructed at levels greater than nine pass the stationarity test. Further analysis indicates that the extraction of time-varying mean wind is most effective at level 5 decomposition.
4. The reconstruction results of non-stationary samples indicate that the stationary wind speed model overestimates turbulence intensity under non-stationary conditions but underestimates the turbulence integral scale. This suggests that the stationary model may fail to accurately capture long-term correlations or large-scale structures due to its assumption of stationarity. Therefore, non-stationary analysis is essential for mountainous regions.
5. Power spectral density analysis demonstrates that wavelet reconstruction effectively removes the low-frequency components of the wind. However, a comparison with classical theoretical spectra reveals a certain degree of deviation between the measured wind spectrum and the theoretical models. This study, based on measured data from the U-shaped canyon bridge site, aims to identify and reveal the primary characteristics of the pulsating wind in the canyon, expand the wind field data for the area, and provide valuable references for the structural wind resistance design in canyon regions. In bridge design, studying non-stationary wind characteristics helps engineers optimize wind resistance strategies for mountain bridges, enhancing their wind resistance and reducing the risk of wind-induced disasters. Additionally, the research results can inform wind-related projects such as wind power generation in mountainous areas. In the future, more measurement points could be added to the bridge site to explore more comprehensive wind characteristics and extend the research to other complex terrains to verify and expand the current findings.  
Conceptualization, Z.S. and F.W.; methodology, Z.S. and F.W.; software, Z.S.; validation, J.W., Z.Z. and X.Z.; formal analysis, Z.S.; investigation, Z.S., J.W. and Z.Z.; resources, F.W.; data curation, F.W.; writing--original draft preparation, Z.S. and Z.Z; writing--review and editing, J.W., X.Z. and Z.Z.; visualization, Z.S. and X.Z.; supervision, J.W.; project administration, F.W.; funding acquisition, F.W. All authors have read and agreed to the published version of the manuscript. This research received no external funding. This research received no external funding. Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author. The authors declare no conflicts of interest.