Basic Research On Field Measurement And Wind Tunnel Test Of Snow On Roof

Snow load is an important factor in engineering design, especially to the large spanspace structure which is sensitive to snow load. However, when it comes to new century,the global climate changes dramatically, and severe weather happens frequently, such assnowstorm. There are increasingly engineering disasters caused by snow load. On theother hand, the current snow load specification exists limitation, and also it is notcomprehensive. Therefore, it is necessary to do much research work about snow load indepth. Consequently, the main work of this paper is focused on the followingfundamental aspects:1. Measure snow density on the ground and roof. Snow is divided into three kinds,and the range of snow density is roughly detemined. By comparing the two’smeasurements, we know the effects of location, snow thickness and temperature onsnow density. Also, we know the differences of snow density between ground snow androof snow, new snow and old snow.2. In order to understand the distribution of snow on roof directly, two buildingswith parapet are chose to investigate. Based on measuring results, the relationshipsbetween the peak of snow depth on roof and snow thickness on ground, the height ofparapet are described. The result suggests the ratio of accumulated snow length andparapet height is a little smaller, which is ruled by snow load code, and advise theratio should be increased to4.3. Standard models are located in ground and building roof which are flat andopen to test snow distribution around them. By comparing cubic models’ results, it isfound that snow distribution around cubic models is related to wind direction, not modelsize in the present experimental conditions, and the quantity of drifting is related towind speed. Snow distribution around cubic model is roughly determined. Throughanalyzing field measurements of stepped flat roof, the windward and leewarddistributions of lower roof are summrised.4. The preliminary research on wind tunnel test which is aimed at snowdrifting iscarried out. A small direct wind tunnel is designed and improved, which is used to studysnowdrift. According to related references, the similarity criteria of wind tunnelexperiments are determined. Based on the similarity criteria, it proves to select finesilica sand as simulated particle reasonably, combined with the theoretical analysis. Thewind tunnel tests of cubic and stepped model are carried out according to fieldmeasurements. By comparing wind tunnel tests with field measurements, they illustratethe applicability of similarity criteria and simulation particle, which are selected to usein wind tunnel test.