Numerical Simulation Of Wind Loads On The Roof Of Low-rise Hip-roofed Buildings

The southeast coastal regions of China are exposed to strong tropical cyclones every year.As a result,wind-induced disasters caused significant property losses and heavy causalities in this region every year.Hip-roofed low rise buildings are common geometry structure forms in southeast coastal regions.But there is no relevant stipulation to the mean wind pressure coefficient of hip-roofed low rise buildings in the load code for the design of building structures(GB50009-2012).Based on numerical simulation,the thesis focuses on the wind pressure distribution and mean wind pressure coefficient in different conditions.The main scope and achievements of this study are as follows:(1)Reviewing a large number of domestic and foreign literatures on wind loads distributions of low rise buildings,including the load codes from China,the USA and Japan,by studying existing data,a general idea of the existing theories and achievements of this subject was concluded,which helps to set up the theoretical basis for subsequent chapters,as well as guiding our further research.(2)Based on ANSYS Fluent 14.5,three turbulent models are selected to conduct the study of the wind loads distributions on the hip-roofed low rise building,of which geometry size is 24m×16m×4m and the slope pitch is 26.7°.The reliability of the three turbulent models is proved,and the most appropriate turbulent model for the following study can be selected by comparing the results.(3)Base on the RNG k-? turbulent model,the numerical simulation of the hip-roofed low rise building is carried out.Regarding the main building parameters such as roof pitch,wind attack angle,and aspect ratio,study is carried out to analyze the wind pressure distribution of the hip roof.The result shows that wind suctions of the windward slope decrease with the increase of the slope pitch and positive pressure appears when the slope pitch is 45°.When the wind attack angle is 45°,the leeward slope suffers a great suction and wind mean pressure coefficient reaches-1.04 which is 2.16 times of the 0° wind attack angle.In different wind attack angle,the mean slope wind pressure coefficient changes from-0.52 to-0.74,with the increase of the aspect ratio from 0.25 to 0.81.(4)Based on the numerical simulation,analysis of the effect of eaves to wind pressure distribution of hip-roofed low rise buildings is performed.The results show that eave does affect both the magnitude and distribution of hip roof pressures.The mend wind pressure coefficients of four slopes decrease slightly with the increase of the length of eaves But the mean wind pressure coefficients of the leeward slope and the two side slopes gradually decrease with the increase of the height of the eaves,while the mean wind pressure coefficients of the windward slope increases at the same time.(5)Based on the numerical simulation,analysis of the interference effect between two hiproofed low rise buildings is performed.The results show that the interfering building does affect the wind load distributions of the interfered building.The upstream building creates the shielding effect to the downstream building,of which wind loads on the roofs decrease.When the wind passes between the two buildings,the slit effect makes the wind loads of hip-roofed buildings increase.