Research Of Snow Dstribution On Roof With Local Obstructions

Extreme ice and snow weather often leads to the destruction and collapse of building structures,resulting in a number of property losses and casualties.Due to the functional and appearance needs,local obstructions are always arranged on various forms of roofs,which makes the roof snow distribution more unfavorable to the structure,and easy to cause damage and destruction of the roof structure.There are some irrationalities in the current load code of our country,which need to be supplemented and improved to ensure the safety of structures.At present,there is a lack of research on the snow distribution on roof with local obstructions in China.This paper compares the relevant provisions of the Chinese and foreign load codes,analyzes the key factors that may affect the snow distribution on roof with local obstructions,and studies the snow distribution on roof with local obstructions through the snow-wind tests and numerical simulation,so as to provide reference for the revision of the load code in China.The main contents of this paper are as follows.First of all,the regulations of snow distribution on roof with local obstructions were compared.The differences and similarities of consideration factors and calculation methods were analyzed,determining two different calculation principles and main influence parameters.The typical examples were calculated to compare the calculation results in different codes.Based on the snow-wind combined experimental facility and the similarity criterion of snowfall model,the influence of wind speed,wind direction,windward roof length,height and width of obstructions,and the across-wind position of obstructions on the snow distribution was compared.The calculation method and concept of the local impact area of obstructions were defined,and the influence of each fact on the roof distribution was obtained.The numerical simulation method based on the snow-wind mixture modeling was used for calculating,using the computational fluid dynamics software Fluent.Four main factors of wind speed,height and width of obstrucions,and windward roof length were analyzed.The influence of each factor on snow distribution on roofs was discussed.Suggestions of code revisions were proposed based on the simulation results and referring to the calculation methods of foreign codes.The key factors such as roof slope,parapet,obstructions array and shape were calculated by numerical simulation.The influence of each factor on the snow distribution of roof with local obstructions was studied.The snow distribution of various complex forms of roofs with local obstructions was studied.