Research Of Snow Distribution On Step Roofs

Step roofs are widely used in the industrial and civil construction,especially in industrial plants,warehouses and other buildings.Step roofs are very sensitive to snow loads,unbanlanced distribution of snow is likely to occur under the combined action of wind and snow,and collapse accidents of step roofs are more frequent in the snow disaster.The current load code of our country only specifies stepped flat roof,and the prescribed form is relatively simple,which should be improved appropriately.At present,the research on distribution of snow on step roofs does not consider the influence of different factors.Contrastive analysis of different load codes was made,and the distribution of snow on step roofs was studied by snow-wind combined tests and numerical simulation.At the same time,snow reduction measures on step roofs were preliminarily explored.First of all,regulations of snow load on step roofs in various codes were compared,and the differences of roof forms and influencing factors were analyzed.The formulars of roof snow distribution coefficient were compared,and typical step roofs structures were calculated in order to find the differences.Based on open air snow-wind combined system,model tests of step roofs were carried out using artificial snow,and the effects of different roof slopes,wind directions and velocities on snow distribution were analyzed.Through the analysis of the test results,snow distribution under different wind velocities and directions as well as the influence of roof slopes was were clarified.The numerical simulation of based on Mixture multiphase flow model provided by Fluent was carried out in order to discuss snow distribution under different roof spans,roof elevation difference and roof length.Suggestions of code revision based on numerical simulation analysis and results of tests was proposed.Through snow-wind tests and numerical simulation,preliminary research on reducing accumulated snow and sliding snow was made,and the efficiency of different measures was studied.According to the research results,feasible measures were proposed to reducing accumulated snow and sliding snow.