ON THE TERM CONTROLLED BY SNOW LOAD: PRACTICAL USE OF SNOW SLIDING ON PITCHED ROOF

摘要

In this study, we examined the reliability of a method for evaluating snow load on a pitched roof that takes into account the occurrence of snow sliding. Data on the properties of adfreezing resistance and frictional resistance, the main resistant forces that determine the occurrence of snow sliding, were summarized form various previous reports. Based on these data, indoor and outdoor experiments were performed. The following results were obtained. 1) The degree of frictional resistance depends on the size of the snow particles. Frictional resistance decreases from about the fifth day after snow has accumulated on the roof, when the snow particles are 1 ～2 mm in diameter (granular snow). 2) Changes in adfreezing resistance depend on changes in atmospheric temperature. There is no adfreezing resistance when the atmospheric temperature rises above the melting point of ice. Based on the data of these two resistant forces, we calculated the number of days require for snow sliding to occur. Changes in atmospheric temperature and the natural rate of snow granulation were used as indices in the calculation. By using our method of calculation, we were able to clarify the number of days required for snow sliding to occur on a building with a pitched roof, indicating that it is possible to design a building for which snow load can be controlled.