Wind Tunnel Study And Numerical Simulation On Characteristics Of Wind Pressures Of Openings In Vulnerable Areas Of Roof Of Low-rise Building

As the situation of global warming is becoming increasingly rigorous,typhoons generate an increase in the number of damage is becoming more and more strong,the low housing especially affected,most of the damage is caused by high pressure and strong winds caused by flying debris building containment system and local damage form damaging the mouth of the cave roof system,makes the house inside and outside surface by wind pressure,for further damage to the building.In this paper,wind load distribution characteristics of local open roof in low vulnerable area are studied by wind tunnel test and numerical simulation.The sensitivity of turbulence model and mesh resolution is analyzed in numerical simulation.Then the turbulence model and mesh resolution are used to verify the accuracy of numerical simulation.At the same time,using the advantage of numerical simulation in model parameter analysis,the influence of hole size,location and other parameters on the wind load mechanism of roof in vulnerable area was analyzed.Firstly,this paper selected three types of roof vulnerable area openings and two forms of characteristic turbulence on the intact roof: separation bubble and conical vortex through the extreme value distribution of low house roof at slope Angle of 18.4°.According to the cloud diagram of wind pressure coefficient distribution on the inner and outer surfaces of the roof under some typical wind direction angles,different positions of roof vulnerable areas have different turbulence mechanisms,which can affect and destroy the original characteristic turbulence to different degrees.In the case of full wind Angle,the internal pressure value is compared with the norms of other countries.It is suggested that the internal pressure coefficient can be 1.0 times the external pressure coefficient of the hole when there is only one dominant opening hole in the roof vulnerable area and the opening rate is between 0.02 and 0.1.The local body type coefficient of roof zoning is compared with China’s regulations.For the windward eave area and leeward roof middle area under the condition of windward roof opening,and the windward roof middle area under the condition of leeward roof opening and the windward gable area away from the hole,the standard value is not safe.And the influence of wind direction Angle on roof shape coefficient is not considered in our country.By taking into account the net extreme wind pressure coefficient distribution of the correlation between the inside and outside of the roof,it is concluded that the eaves gable area,roof corner area and roof ridge gable area of threekinds of open roof have the most unfavorable extreme value,so this area should be strengthened appropriately in the structural design.Second,the numerical simulation model with open roof square hole in the wind tunnel model for benchmark model,based on the four kinds of turbulence model and three kinds of mesh size,sensitivity analysis it is concluded that SST k-ω best agreement with wind tunnel test data and the turbulence model,and then to 0°to 90°direction Angle of the roof,both inside and outside surface of the typical points comparing with the results of wind pressure and wind tunnel simulation results,the results show that this numerical method can accurately reflect the roof open holes of low house roof of wind pressure distribution law.Finally,numerical simulation was used to study the roof vulnerable area and wall window at the same time open holes of low building roof inside and outside surface wind pressure,analyses and discusses the single wall open hole position,single wall open hole rate and double side wall at the same time open hole for parameters on low housing vulnerable area open a hole in the roof local part of the wind pressure effect,analysis under the typical wind Angle,the working condition of different open hole outside the windward wall split open hole hole in the roof pressure had a greater influence on the local,open hole rate for open hole in the roof clean air pressure is affected,oblique direction of the windward wall open hole makes the leeward roof ridge corner area net wind pressure amplifier,reached 2.1.This area is most likely a secondary vulnerable area.