Field Measurements And Wind Tunnel Tests Of Wind Effects On Low-rise Buildings During Typhoons

China has been frequently and seriously influenced by tropical cyclones.Previous wind-related disaster investigations indicated that most destroyed buildingsduring disasters were low-rise buildings, which caused significant property losses andheavy causalities. Hence, there is an urgent need to understand the wind loadingcharacteristics generated on low-rise buildings exposed to typhoon conditions. In thisthesis, the wind load characteristics on low-rise buildings during typhoons werestudied through field measurements and wind tunnel tests. The objective of the studyis to further understand typhoon-generated wind characteristics and wind loads onlow-rise buildings during tropical storms. The major objective and achievements ofthis study are as follows:(1) A full-scale instrumented low-rise building with flat roof, with width(B)×length(L)×height(H)=4m×6m×4m, has been built to monitor the wind velocityfields and building surface pressures during typhoon landfalls. Based on the fieldmeasurement of wind data during severe typhoon Utor, mean wind speed and windturbulence characteristics of typhoon winds in surface boundary layer were obtained.The correlation between gust factor and turbulence intensity was fit based on themeasurements. Moreover, the results of extreme suction pressure coefficients werestudied through analyzing the measured data, and a further study of non-Gaussianbehavior of the pressure coefficients were discussed as well. The results showed thatthe gust factor increased with increasing turbulence intensity. The power spectra oflongitudinal wind speed were studied and it was found that the measured spectra weremost consistent with the Karman spectrum. It revealed that high local suctions on thewindward corner of the roof were observed under oblique flows, and the probabilitydistributions of the measured pressure coefficients and peak factor showed obviousnon-Gaussian behavior.(2) Field measurements of wind effects on a full-scale instrumented low-risebuilding with gable roof were also conducted. The measurements of the wind velocityfield around and the wind-induced pressures on the building during the passage ofsevere tropical storm Rumbia were presented. Near-ground wind characteristics suchas mean wind speed, wind direction, turbulence intensity, gust factor, turbulenceintegral length scale and spectra were investigated. Moreover, the wind-inducedpressures on the roof of the building were analyzed and discussed. The results revealed that the eave and ridge edges on the roof were subjected to the most severesuction pressures under quartering winds. The probability distributions of pressuredata and associated peak factors were found to follow the type I extreme valuedistribution and the Weibull distribution, but deviated significantly from thelognormal distribution.(3) Wind tunnel tests were conducted to study the wind loading characteristicson the two experimental buildings. Detailed comparisons of the model tests and thefield measurements have been investigated. Meanwhile, this paper also discussed theeffects of different terrain conditions on the wind pressures on the roofs of thelow-rise buildings. It was observed that the wind pressure coefficients increased withincreasing terrain roughness length and high local suctions were observed on the eavecorners and ridge corners under quartering winds. Wind tunnel test resultsunderestimated the field measured negative peak pressure coefficients in separatedflow regions and conical vortex regions.The outputs of this study, in particular the field measurements from the twoinstrumented low-rise buildings during typhoons, are expected to be useful for furtherunderstanding of the characteristics of near ground wind field and building surfacepressures during tropical storms. Furthermore, they provide valuable information onthe wind-resistant design of low-rise buildings in tropical cyclone-prone regions.