C-130 testings on low-rising buildings

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Title: C-130 testings on low-rising buildings
Author: Zhu, Hongchao
Abstract: Investigations of wind -induced building damage have shown that roof and roofing systems are the most vulnerable parts of the whole building envelope to fail . Damages to the roof typically initiate around the roof corners and edges where extremely high suctions occur due to the flow separation . In an effort to improve the structural performance of buildings in strong wind events we studied building behavior at near ultimate wind loads . This work focuses on controlled full -scale experiments using the propellers of a C -130 aircraft to generate the flows . Testing was carried out on two low -rise residential constructions , in particular , a manufactured home and a modular home . In this test , a Hercules C -130 aircraft was used to generate simulated wind events . The flow characteristics , induced external and internal pressures , and selected structural responses were measured during each event . In order to obtain the influence of building on the reference pressure , barometric and wind speed measurements , two wind tunnel tests were performed in Texas Tech Wind Tunnel . The experiments confirmed some differences in turbulence intensities , roughness length , integral scales and spectra of flows existed between C -130 generated flows and atmospheric boundary layer (ABL ) flow in open terrain . In general , the C -130 flow was less turbulent than the ABL flow . As to the pressure distribution over the manufactured home and modular home , some scatter of the data is evident for runs conducted at lower flow speeds , but data from runs at higher flow speeds show little scatter . Compared to ASCE 7 -02 , it was found that ASCE7 -02 (MWFRS ) provided an upper limit to current results . However , a few exceptions occurred on the roof leading edge . The results of full scale C -130 tests were consistent with that of wind tunnel tests , full scale natural wind tests and other similar research . The existence of the test specimens had a significant influence on the wind speed measurement especially when the wind speed anemometers were close to the buildings . When wind speed anemometers were behind the building , the measured wind speed decreased almost 50 % . When wind speed anemometers were in the front of windward walls , the recorded wind speed was about 10 -15 % less than non -influenced wind speeds . While , with wind speed anemometers located on the side of building models , the influenced of the buildings can be ignored . In the full scale tests , the influence of the buildings on reference pressure measurements needs to be considered and the correction of its influence is necessary . When the reference pressure pit was located directly in front of windward wall , the reference pressure pit experienced pressures higher than that in the free stream flow field . Whereas if the reference pressure pit was located beside the sidewall , the reference pressure pit experienced lower pressures . As to the influence of buildings on barometric pressure measurements , it only influences the calculation of air density less than 1 % , so it is reasonable to ignore it . This work was performed under the Department of Commerce NIST /TTU Cooperative Agreement Award 70NANB3H5003 .
URI: http : / /hdl .handle .net /2346 /964
Date: 2006-05


C-130 testings on low-rising buildings. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /964 .

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