Analysis On The Characteristics And Mechanism Of Wind-driven Rain In Low Rise Buildings Under The Combined Action Of Wind And Rain

In the southeast coastal area of China,it is common for low-rise buildings to be damaged under severe storms and extreme weather conditions.The wind-driven rain effect under the combined action of wind and rain is one of the important reasons for such disasters.Therefore,this paper mainly studies the distribution of wind-driven rain characteristics of low-rise buildings in the wind rain flow field,and analyzes the internal mechanism of wind-driven rain damage from the perspective of flow field.Firstly,a rainfall event at a site in Norway was selected to verify the Euler-Euler method of numerical simulation of wind-driven rain.The results showed a high degree of agreement with the measured data,which verified the effectiveness of the Euler-Euler method in the study of wind-driven rain for low-rise buildings.Then,the TTU standard model of low-rise buildings was selected as the research model of wind-driven rain field.Based on the analysis of several common turbulence calculation models,a model that predicts better than WERFL measured data and TJ-2 wind tunnel test—Realizable k-ε algorithm is obtained,which provides experience and method support for the development of wind-driven rain effect of low-rise buildings.The numerical simulation study was carried out on a single low building under nine wind-driven rain conditions,namely wind speed of 5m/s,10m/s,15m/s,rainfall intensity of16mm/h,64mm/h and 100mm/h.The results show that the grabbing rate and wind-driven rain pressure on the top corners of the windward side of low-rise buildings are the largest,and the maximum wind-driven rain pressure is 19.06 Pa in nine working conditions when the wind speed is 15m/s and the rain intensity is 100mm/h.The additional load of rain phase in the wind and rain field can not be ignored.Therefore,the load check calculation on the top of the building should be considered in the architectural design to improve the design strength and increase the safety of the building.The group building layout is respectively studied for low-rise buildings with front-to-back layout and left-to-right layout.Under a rainfall event with a wind speed of10m/s and a rainfall intensity of 100mm/h,numerical simulations of wind-driven rain were carried out under six working conditions with a distance of L=3m,6m,and 9m.The results of wind driven rain simulation of group layout show that the distribution law of characteristic quantities obtained by the numerical simulation of the front row or the left and right rows of low-rise buildings is similar to that of single building,and its value is slightly smaller than that of single buildings.The eigenvalue distribution obtained by numerical simulation of the back row buildings is equal to and smaller than that of the front buildings,and the eigenvalue distribution in the area higher than the front row buildings approximately shows a trend of gradually increasing from the middle to the surroundings.The narrow channel effect is formed between the two rows of buildings,and the characteristic quantity of wind-driven rain on the inside of the narrow channel is generally greater than that on the outside.Therefore,the layout of the group building should appropriately increase the safety spacing to avoid the adverse effects of the airflow blocking effect and the narrow channel effect.This study will have important practical significance for the prediction and early warning of wind and rain disasters in low-rise buildings,pre-disaster evacuation,post-disaster planning and reconstruction,and supplementation and improvement of relevant building load regulations.