Field measurements of snowdrift characteristics on reduced scale building roofs based on the size effect study

Unbalanced snow distribution, which leads to an excessive snow load in a local area, is one of the main reasons for building collapses. The formation of uneven snowdrifts is closely related to the shape of the building as it seriously affects the turbulent structure and drifting snow process. Unfortunately, the design codes of different countries for applying snow load on building structures cannot give a clear explanation because of the discrepancies between them. Therefore, a series of reduced scale field measurements of snowdrifts on roofs were conducted to clarify such discrepancies. Firstly, the size effect of model scaling was investigated by observing snowdrifts around two models with a scale ratio of 1/2. The results show that the size effect has little influence on the snowdrift pattern on the premise of satisfying the similarity criterion. Thereafter, the snowdrift characteristics of two-level roofed and gable roofed buildings were explored and analyzed through the comparison with different national load codes and collapsed building cases. Overall, the provisions of the Chinese load code differ from the measurement results, which leads to an underestimation of roof snow load. ISO 4355 and Canadian NBC codes could give a better prediction of the snow load by comparison.