Numerical Simulation And Experimental Study Of Snow Distribution On Typical Roofs

There were many meteorological disasters caused by ice or snow in China in recent years that caused damage to roofs, economic and fatalities. This has attracted researchers'interests in examining the design snow loads recommended in the national building code. Unfortunately, for this research, the required statistical information is scarce except those gathered by some meteorological stations. Site-measurement of snow density and depth is carried out in this study. Also, a numerical model for simulating the snowdrift on typical roofs is developed using the commercial CFD software Fluent 12.1.First, comparison of recommended snow loads in the Chinese code, the ASCE's code, the Canadian code and the Eurocode is presented. Differences between the recommended snow loads in these codes are pointed out in terms of the basic formula to calculate the snow loads, the critical slope, and the snow loads on arched roofs and stepped roofs. Suggestions and the needed researches for the calibrating the Chinese code are given.In the third chapter, snow density and snow depth both on the ground and on building roofs are measured while three model roofs with different slopes are made to check the critical slope for snow load. It is found that: 1) snow density is in direct proportion to environmental humidity, snow depth and snow age, and, the snow density on roofs are much higher than that on the ground; 2) additional snow deposition behind the parapet wall is frequently observed and 3) the critical slope for snow load can be risen to 70°.To carry out numerical simulation, experimental and wind tunnel test results given in the literature are used to aid the identification of the motion modes and spatial distribution characteristics of drifting snow. The identified features are then modeled using the SST k-ωturbulence model and the Mixture multiphase model provided by Fluent. Applying this numerical model, the snow distribution patterns on the parapeted gable roofs, the multi-gable roofs and the stepped roofs (with different size parameters such as widths, slopes, roof height differences and so on) are simulated. Snow distribution characteristics on these roofs are derived from the simulation while the influences of the size parameters are analyzed.