# Research on Snow Load Characteristics on a Complex Long-Span Root Based on Snow-Wind Tunnel Tests
## 5 Conclusions  
This study has demonstrated the feasibility of snowdrift reproduction based on the air-snow-wind combined experimental system and the experimental approach. A series of scaled tests were carried out to predict the wind-snow flow behavior on a complex membrane roof. The snow distribution characteristics were decomposed and analyzed, and the following results were obtained. (**i**) The similarity criterion based on the drifting snow flux in the saltation layer was proved to simulate the overall snow distribution effectively. Based on the validated similarity criterion, the snowdrift distributions on a complex long-span membrane roof under different inflow directions were reproduced by using artificial snow particles. The results preliminarily explained the influence of the roof shape and wind direction on the snowdrift, and illustrated the complexity of the snow distribution on the complex roof, compared with that on a simple roof. (**ii**) Based on the EOF analysis, the snow distribution on the complex roof under different inflow direction conditions was broken down into several spatial distribution modes and wind direction-dependent weighted coefficients. Through the analysis of spatial modes, it was proven that the snow load distribution on a complex roof can be broken down into an integral surface load and local concentrated load. Combined with the roof pattern, it was demonstrated that the snow distribution on a complex roof can be decomposed into the snow distributions on several simple roofs according to the specific roof form. (**iii**) Through the significance analysis of the main spatial modes, it was demonstrated that the local roof shape has the greatest influence on the snowdrift on the complex roof; whereas, the contribution of the whole roof shape to the snowdrift depends on the dominant wind direction. The closer the wind direction represented by the spatial mode is to the dominant wind direction, the greater its contribution to the overall result. In practice, when no reference is available in the load code, the actual roof snow load can be estimated preliminarily by reasonable combinations of the existing simple roof snow loads in the codes, referring to the specific roof form and the dominant wind direction.  
Conceptualization, F.F. and S.S.; methodology, G.Z.; software, G.Z.; validation, G.Z., Q.Z., and F.F.; formal analysis, G.Z.; investigation, G.Z.; resources, F.F.; data curation, Q.Z.; writing--original draft preparation, G.Z.; writing--review and editing, G.Z.; visualization, Q.Z.; supervision, F.F.; project administration, S.S.; funding acquisition, F.F.  
This was funded by the Chinese National Natural Science Foundation project (51927813, 51978207) and the National Science Fund for Distinguished Young Scholars (51525802).  
The authors are grateful to the members of the Space Structures Research Center at the Harbin Institute of Technology, for providing invaluable information and advice in this study.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.