# Research on Snow Load Characteristics on a Complex Long-Span Root Based on Snow-Wind Tunnel Tests
## 1 Introduction  
Snow-induced building collapse occurs frequently in long-span structures; for example, the collapse of the Katowice Trade Hall (Poland, 2006), the collapse of an ice rink in Bad Reichenhall (Germany, 2006), and the collapse of the Minnesota Vikings membrane stadium (USA, 2010). The sudden increase in the snowfall and unbalanced snow distribution, which leads to an excessive snow load in a local area, are the main reasons for such collapses [(1)]. Unfortunately, the snow load requirements are only provided for the design of buildings with certain simple roofs (e.g., flat roof, pitch roof, and gable roof, among others) in different national load codes [(2; 3)], and few requirements are available for long-span structures. It is usually suggested that the snow load distribution coefficients for large or special-shaped buildings be defined following specific research or experiments in certain national codes [(4; 5)]. In terms of the related special research methods, the computational fluid dynamics (CFD) method and wind tunnel experiment are usually adopted for the practical design of snowdrifts on or aroundbuildlings [6; 7]. In the field of CFD research, [PERSON] et al. [6] analyzed the snowdrift around an actual apartment building based on the revised \(k\)-\(\varepsilon\) model. In this study, the transport equation of snow concentration was solved only for snow particles suspended in the air. [PERSON] et al. [8; 9] predicted the snow distribution on the curved roof of a sports hall under specific weather conditions. Generally, the overall snowdrift pattern fitted the measured result well and the location of end effects was reproduced close to the side edge of the roof. [PERSON] et al. [10] simulated the snowdrift development around a group of surface-mounted buildings and elevated structures, respectively. The analysis assisted the conceptual building design process to manage potential snowdrifts on and around these structures. The application of the CFD technique to snowdrift problems can provide detailed information on the relevant flow and phase variables in the entire calculation domain under well-controlled conditions and at a low cost. Unfortunately, the numerical technique is mainly applied to the snowdrift on small-scale roofs with usual shapes or simplified long-span roofs, as the large scale and fine structural details of complex roofs require higher resolution and higher quality grids. Cases with finer grids would be more time consuming, and the accuracy will be reduced if the grid quality is poor. Therefore, rare work was carried out on the snowdrift on complex long-span roofs by using the CFD method. In the field of experimental research, [PERSON] et al. [11] examined snowdrift formation on the lower level of a large-area two-level roof in different-surface shear stress and terrain roughness conditions. [PERSON] et al. [12] explored the hazard and alleviating measures of the snowdrift around the Concordia Antarctic research station by using real snow particles in the Jules Verne climatic wind tunnel. [PERSON] et al. [13] performed a series of snow load tests for three different complex roofs of sports facilities. Snow precipitation and wind-induced redistribution were simulated by using powdered polystyrene foam as artificial snow. The results of snow load distributions were presented for the practical structural design. Compared with the CFD method, this experiment can reproduce the snowdrift mechanism to the greatest extent and restore every detail of the building. Unfortunately, the required equipment is not always available and is usually expensive for experimental preparation and model creation. Therefore, it greatly limits the large-scale application of the experimental method in the study of snowdrift problems.