全部 标题 作者
关键词 摘要

Buildings  2012 

Systematic Study of the Failure of a Light-Frame Wood Roof in a Tornado

DOI: 10.3390/buildings2040519

Keywords: Tornado, fragility, EF rating, roof failure, residential structures, light-frame

Full-Text   Cite this paper   Add to My Lib

Abstract:

Tornadoes are a particularly devastating natural hazard that affect communities across the United States, particularly the Midwest and South. They are unique from an engineering point-of-view due to their very low probability of occurrence but often highly destructive consequences. The 2011 season was particularly devastating to the Southeastern portion of the U.S. This paper presents a single case study of a 2012 tornado that struck a single large rural light-frame wood house with an unconventional roof system. A fragility methodology was used as a tool to probabilistically study the loss of the roof system, and bound an Enhanced Fujita (EF) scale rating of the tornado. The tornado was initially rated as an EF3 tornado by the U.S. National Weather Service. However, following a detailed site inspection verified with numerical structural models, the tornado was downgraded to an EF2 tornado. As expected, the use of nail connections in a roof-to-wall connection resulted in a weaker link compared to a hurricane clip. The approach presented in this paper can be used as a supplement to the EF rating provided by U.S. National Weather Service meteorologists when unusual conditions in either the structure or surroundings exists.

References

[1]  National Climatic Data Center U.S. Tornado Climatology. Available online: http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html (accessed on 25 March 2012).
[2]  NOAA Severe Weather Safety: Tornado Guide. Available online: http://www.nssl.noaa.gov/edu/safety/tornadoguide.html (accessed on 24 March 2012).
[3]  Changnon, S.A. Tornado losses in the United States. Nat. Hazards Rev. 2009, 10, 145–150, doi:10.1061/(ASCE)1527-6988(2009)10:4(145).
[4]  Van de Lindt, J.W.; Pei, S.; Dao, T.; Graettinger, A.; Prevatt, D.O.; Gupta, R.; Coulbourne, W. A dual-objective-based Tornado design philosophy. J. Struct. Eng. ASCE 2012. in press.
[5]  NOAA 2011 Tornado Information. Available online: http://www.noaanews.noaa.gov/2011_tornado_information.html (accessed on 25 March 2012).
[6]  NOAA National Climatic Data Center State of the Climate: Tornadoes for Annual 2011. Available online: http://www.ncdc.noaa.gov/sotc/tornadoes/2011/13 (accessed on 24 March 2012).
[7]  Davies-Jones, R.P. Tornado dynamics. In Thunderstorms: A Social and Technological Documentary; Kessler, E., Ed.; University of Oklahoma Press: Norman, OK, USA, 1986; pp. 197–236.
[8]  Forbes, G.S. Meteorological aspects of high-impact Tornado outbreaks. In Symposium on the Challenges of Severe Convective Storms, Atlanta, GA, USA, 29 January–2 February 2006.
[9]  Minor, J.E.; Mehta, K.C.; McDonald, J.R. Failure of structures due to extreme winds. J. Struct. Div. 1972, 98, 2455–2472.
[10]  Minor, J.E.; Mehta, K.C.; McDonald, J.R. Air Flow around buildings as reflected in failure modes. ASHRAE Trans. 1976, 82, 1061–1071.
[11]  McDonald, J.R.; Mehta, K.C.; Minor, J.E. Tornado-resistant design of nuclear power plant structures. Nucl. Saf. 1974, 15, 432–439.
[12]  Ellingwood, B.R.; Rosowsky, D.V.; Li, Y.; Kim, J.H. Fragility assessment of light-frame wood construction subjected to wind and earthquake hazards. J. Struct. Eng. 2004, 130, 1921–1930.
[13]  Haan, F.L.; Balaramudu, V.K.; Sarkar, P.P. Tornado-induced wind loads on a low-rise building. J. Struct. Eng. 2010, 136, 106–116.
[14]  American Society of Civil Engineers (ASCE). Minimum Design Loads for Buildings and Other Structures; ACSE: Reston, VA, USA, 2010.
[15]  Sengupta, A.; Haan, F.L.; Sarkar, P.P.; Balaramudu, V. Transient loads on buildings in microburst and tornado winds. J. Wind Eng. Ind. Aerodyn. 2008, 96, 2173–2187.
[16]  Alrasheedi, N.H.; Selvam, R.P. Tornado forces on different building sizes using computer modeling. In ASME Early Career Technical Conference, Fayetteville, AR, USA, 31 March–2 April 2011.
[17]  Selvam, R.P.; Millett, P.C. Computer modeling of tornado forces on a cubic building using large eddy simulation. J. Ark. Acad. Sci. 2003, 57, 140–146.
[18]  Rosowsky, D.V.; Ellingwood, B.R. Performance-based engineering of wood frame housing: Fragility analysis methodology. J. Struct. Eng. 2002, 128, 32–38.
[19]  Lee, K.H.; Rosowsky, D.V. Fragility assessment for roof sheathing failure in high wind regions. Eng. Struct. 2005, 27, 857–868.
[20]  NOAA National Weather Service: Weather Forecast Office. Available online: http://www.srh.noaa.gov/bmx/?n=event_01232012koffman (accessed on 25 March 2012).
[21]  McDonald, J.R.; Mehta, K.C. A Recommendation for an Enhanced Fujita Scale; Wind Science and Engineering Center, Texas Tech University: Lubbock, TX, USA, 2006.
[22]  Ellingwood, B.R.; Tekie, P.B. Wind load statistics for probability-based structural design. J. Struct. Eng. 1999, 125, 453–463.

Full-Text

comments powered by Disqus