Wind-resistant Performance Study On Low-rise Building In Typical Mountain Terrain

In China's coastal areas,the destruction and collapse of houses caused by typhoon will directly lead to casualties and huge property losses.These destroyed buildings mostly are the low-rise buildings.Therefore,to improve the maintenance system of wind-resistant design will directly reduce the loss of wind storm.To make acquaintance of wind load characteristics of low-rise building,especially the wind load characteristics of the roof system are of great significance.All these results indicated that the wind loads acting on low-rise buildings only considered the isolated low-rise building condition or architectural complex low-rise buildings group condition in computer simulation situation.The study on the wind resistance of low-rise buildings by wind tunnel tests and field measurement techniques in typical mountainous terrain is scarcely involved.In order to solve the above problems,this paper applies the wind tunnel test,numerical simulation and field measurement,theoretical research and so on to deeply and systematically analyze the distribution regularities of surface wind pressure,disturbance effect,partition shape coefficient,surrounding flow field distribution,actual wind effect,peak wind pressure coefficient estimation,non-Gaussian distribution characteristics and other issues.The main contents of this paper are as follows:The wind pressure distribution of model scale of low-rise building in typical mountain terrain of coastal arears are studied with pressure measurement wind tunnel tests.The study mainly focuses on the variation of average pressure coefficient and shape coefficient with the change of spacing between the hillside and building,hillside height,hillside slope under wind attack of 0°,then the trends of average wind pressure coefficients of low-rise building under wind attack of 0°~ 90 °is analyzed.Some parts should be paied more attention in the design for their larger absolute value of the average pressure coefficient;It has a great relationship between mean pressure coefficient under different wind angles and mountain environment.The most unfavorable wind angle of wind load calculations should be taken into consideration of the design of low-rise building.Based on the CFD numerical simulation,the peripheral flow field of the isolate low-rise building and low-rise building in hillside terrain is analyzed,summarizing the circumstances of the surrounding flow field as the hillside slope and spacing between the hillside and building change.And the air flow by the mountain after the interference of the form of a detailed analysis,summarizing the law of airflow.In order to explore wind pressure characteristics of low-rise building with gable roof,Wind-tunnel test and field measurements on a full scale model of low-rise building built in coastal area are carried out to discuss pressure behavior and wind pressure distribution pattern.The result clearly demonstrates that wind pressure behavior(mean wind pressure coefficient and fluctuating wind pressure coefficient)of wind tunnel test is roughly agrees with that of field measurement.When wind blows toward the corner of low-rise building,the pressure distribution on the surface of walls and roof coincides well with that got in the field measurements.The value of field measurement is greater on both windward wall of the corner area and flat area on windward roof than that obtained via the wind tunnel test.Field measurements are performed on a low-rise building on island slope terrain during the passage of typhoon Morakot to study the building's pressure characteristics,including the near-surface wind behavior and wind pressure distribution.Simultaneously,wind-tunnel measurements based on the measured data of the wind field on island slope terrain are taken for comparison.The result clearly demonstrates that the wind-pressure distribution pattern on the low-rise building surface is complex owing to the great influence of the surrounding landscape.The pressure of some measuring points may appear negative and positive on the windward and leeward slopes,respectively.Simultaneously,wind-tunnel measurements at a scale of 1:40 based on the measured data of the wind field on island slope terrain are taken for comparison.The mean pressure coefficient's wind pressure behaviors agree well between wind-tunnel and field measurements,especially on the windward slope.The wind-pressure coefficient behaviors also agree well,although the absolute value of the field measurement is larger than that of wind-tunnel experiment.At present,China's "building structure load specifications"(GB50009-2012)Table 7.3.1 wind load body coefficient of the second and twenty-fourth terms proposed a rule of wind load body coefficient for closed double slope roof,mountain closed double slope roof based on the complexity of mountainous land forms.But the reference range of China's "building structure load specifications" has great limitations.Compared the specified size factor in the specification with the body size coefficient calculated by the wind tunnel test to make reasonable amendments to the proposal.Meanwhile,reference to the requirements of the load structure specification of Japan and the United States to redefined the partition of the body size coefficient and compared with the model and then render some suggestions on the body size partition.To analyze the representative testing point's changes of pulsating wind pressure power spectrum under different operating conditions to discuss main influencing factors of the pulsating wind pressure which includes the turbulence characteristics of the longitudinal pulsating winds and the eddy current turbulence and characteristic turbulence caused by the structural surface and the cause of the pulsating wind pressure under different operating conditions is different.Based on the analysis of the non-Gaussian characteristic of the roof surface to propose the non-Gaussian discriminant criterion and the non-Gaussian region of the roof.