Snowdrift Action And Response Of The Flat Roof Structural

Due to light weight and small stiffness,the large-span roof structure is sensitive to wind and snow loads,so as for structural design,the special attention should be paid to.However,the current load codes and standards are only applicable to simple forms of roof for both types of loads,which do not consider the uneven distribution of snow loads under the effect of wind field,nor do they take into account the effect of wind and snow on the structure.These factors,to some extent,led to the collapse of the roof structure.The main methods for the research of building roof snow flow effect include field measurements,wind tunnel tests and numerical simulations.The research objects mainly include flat roofs,stepped roofs,double slope roofs and arched roofs,However,there is a lack of systematic parametric analysis of a particular roof form,and the mechanism of snow drifting on roof needs further study.This paper first briefly review the research status at home and abroad from the aspect of research methods,and summarize the relevant basic theories of wind-induced snow drifting,then combine the wind tunnel test and numerical simulation methods to study the distribution characteristics of snow on flat roofs.Based on this,the response characteristics of the structure under the joint action of snow and snow are studied.The main work is as follows:(1)Combining with the theoretical background of wind-blown sand,through the analysis of the snow particles,the expression of the critical start-up wind velocity of snow particles was deduced,and a simplified snow particle jump trajectory model was given.(2)Based on similar theoretical requirements,the wind tunnel experiment was conducted to study the characteristics of snow redistribution on flat roofs where the silica sand was used to simulate snow particles.The influence of roof span and wind speed variations on the overall shape of snow,snow depth coefficient,mass transport rate,and mass flow rate were studied seriously.(3)Combining with the Mixture multiphase flow model and quasi-dynamic algorithm,the snow redistribution of the flat roof under 6m/s velocity condition was simulated in FLUENT.And the temporal variation characteristics of the snowbound boundary were analyzed,and the wind tunnel test results was used to verify the validity of the numerical method.(4)Based on the oblique refraction technique,the snow redistribution pattern of the roof was obtained after the wind tunnel test.A numerical calculation of roof model with different snow forms was established,and the disturbance characteristics of the snow pattern on the flow field were analyzed.(5)Taking a single-layered planar grid structure as an example,the dynamic response characteristics of the structure under combined action of wind and snow loads are compared by numerical simulation,in which the snow shape on roofs and the additional snow mass were considered.