| In recent years,snow and ice disasters occur frequently in China,and snowrelated engineering disasters are increasing.It was found that the wind-induced snow drifting caused the unbalanced distribution of snow on the roof,leading to the excessive local snow load,which was the main reason for the construction accidents caused by snow.The current load code of building structures in China provides the corresponding snow load factors for some conventional roofs with simple forms,but for the large public buildings such as transportation hubs,stadiums and exhibition centers,it is difficult to determine the snow load factors according to the suggestion of the code because of their large span and complex forms.Therefore,it is of great scientific significance and engineering guidance to research on the distribution rule of snow on the complex long-span structure roof.At present,the research on roof snow cover mainly adopts the analysis method based on a single event,which cannot consider the changes of local meteorological conditions.This paper establishes a roof snow time-varying analysis method based on the actual historical meteorological data,using the Finite Area Element method to calculate snow distribution daily.Then the most unfavorable condition could be extracted in the unit of year,and the snow load factors with clear probability could be given through extreme value analysis,which could be used for the design of structure limit state,providing a reference for the design of snow load in similar projects.The main research contents of this paper are as follows:(1)The Fundamentals and Validation of Finite Area Element Method.The fundamentals and calculation method of the Finite Area Element method for simulating wind-induced snow drifting are described.The CFD numerical simulation method is used to simulate the wind field of roof,and the wind-induced snow distribution result of the roof could be calculated by FAE method using these wind field data.The wind tunnel results and actual measurement results are compared to verify the validity of the FAE method in simulating wind-induced snow drifting results.(2)The Method for Analyzing the Process of Roof Snow Distribution Based on Historical Meteorological Data.According to the meteorological data of actual snow depth,temperature,and wind data,this paper considers various meteorological factor which could influence the intensity of wind-induced snow drifting,researches on the effective use of various meteorological elements,to obtain the roof snow distribution changes on time scales.(3)Research on the Snow Load Factors of Typical Roofs.This paper takes stepped roofs,gable roofs,and arched roofs as examples,calculates the roof snow distribution on time scales according to the historical meteorological data of Harbin.Then the most unbalanced situation is extracted in the unit of year,and the probability analysis method is adopted to determine the most unfavorable snow load factors with a regression period of 50 years as the design value of the snow load factors of the typical roofs,which can be used for the limit state design of the corresponding structure. |
