Ice Accretion in Freezing Rain.
Ice accreted on structures from freezing rain causes both increased vertical loads and increased wind loads, due to the larger projected area of the structure. Structural failures initiated by ice loads frequently cause millions of dollars of damage to overhead power and communication lines, towers,...
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| Format: | Text |
| Language: | English |
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1996
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| Online Access: | http://www.dtic.mil/docs/citations/ADA310659 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA310659 |
| Summary: | Ice accreted on structures from freezing rain causes both increased vertical loads and increased wind loads, due to the larger projected area of the structure. Structural failures initiated by ice loads frequently cause millions of dollars of damage to overhead power and communication lines, towers, and other ice-sensitive structures. There is little information on ice loads to use in the design of these structures, so freezing-rain models have been developed for use with weather measurements to determine the severity of accreted ice loads from historical data. This report describes a detailed heat-balance ice accretion model, including the important heat fluxes in freezing rain and allowing the accretion of runoff water in the form of icicles. It also presents a simple algorithm for calculating the ice load on components with different diameters and cross sections. Collision efficiency in freezing rain and the calculation of the wind-on-ice load are also discussed. Model results are compared with the ice load measured during a recent freezing rain storm, and to each other, using 45 years of weather data from Des Moines, Iowa. |
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