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Related Concept
  • air barrier
  • load on building envelope
  • wind driven rain
  • wind induced pressure on building
  • wind-driven rain: CFD models



  • Related Articles
  • Centre for Building Studies, Concordia University
  • Journal: International Journal of Wind and Structures
  • Journal: Wind and Structure
  • Journal: Wind Engineering
  • The Saffir-Simpson Hurricane Scale
  • wind and how to measure: What Causes Wind? And How is Wind Measured?
  • Wind tunnels
  • wood thermal conductivity vary with temperature
  • sheathing again high wind: Wood Wall Sheathing Advantages

  • Concept:

    wind

    *Development of Wind

    Wind usually refers to the movement of air parallel to the earth's surface.

    The driving forces of winds in the lowest few hundred feet of the atmosphere are pressure differences caused by unequal heating of the air. The direction is also affected by the Coriolis force. Normally, wind requires several hours to develop.

    *Velocity Profile

    The roughness of the earth's surface causes the surface wind speed to be much less than the wind speed at higher levels. Velocity profiles have been determined by fitting curves to observed mind speeds at several levels, is described by a power law of the form:

    Vh = Vr*(h/hr)^k

    where Vh is the mean wind speed at height h above the ground, Vr is the mean speed at the reference height h (10 metres or about 30 feet is internationally recommended as the standard), above the ground, k is the exponent for the best-fitting curve.

    *Turbulence in Surface Winds

    Superimposed on the mean speed are gusts and lulls. These gusts have a random distribution over a wide range of frequencies and amplitudes, both in time and space.

    *Design Wind Speeds

    The basic design wind load in the National Building Code of Canada is the velocity pressure of a wind lasting for a few seconds that will be exceeded on the average once in 30 years.

    Wind loads have become particularly significant because of the increasing number of high-rise buildings. Other factors have also contributed to the importance of wind in design: light-weight low-slope roofs, curtain wall construction and the appearance of special structures having "aerodynamic shapes."

    Wind loads have become particularly significant because of the increasing number of high-rise buildings. Other factors have also contributed to the importance of wind in design: light-weight low-slope roofs, curtain wall construction and the appearance of special structures having "aerodynamic shapes."



    Tidbits






    Web Links (4): Notes
      This link was checked on Dec. 2006National Wind Technology Center
      "research facility managed by NREL.. researchers work with members of the wind energy industry to advance wind power technologies that lower the cost of wind energy... wind turbine designs."

      This link was checked on Dec. 2006RCI-Mercury - Resource for Roofing and Waterproofing Information
      Excellent "online roofing and waterproofing document resource. " on Coatings Codes, Associations, Standards, Wood Expansion Joints, etc.; ...technical journal of the Roof Consultants Institute.

      This link was checked on Dec. 2006Weather data viewer
      "Design conditions were determined for 509 US, 134 Canadian, 339 European, 293 Asian and 169 other worldwide locations for a total of 1444 locations. Thirty-three years of hourly weather data were used for approximately 1/2 of the US and all of the Canadian locations. Twelve years of data were used for the other locations. "

      This link was checked on Dec. 2006WMO - World Meteorological Organization
      "... coordinates global scientific activity to allow increasingly prompt and accurate weather information and other services for public, private and commercial use, including international airline and shipping industries."

    Related References (14)
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    Chaotic fluctuation in natural wind and its application to thermal amenity, by Hara, T., Shimizu, M., Iguchi, K. and Odagiri, G., 1997
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    Damage, shelter, and other performance issues for buildings in high wind regions, by Rosowsky, D. V. and Schiff, S. D., 2002
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    Inaccuracies in standard meteorological low-speed wind data, by Levermore, G., C. Sanders, J. Dewsbury, A. Gadian and P. Laycock, 2001
    wind and hurican on roof
    Keeping roofs on and working, by Paroli, R. and Baskaran, A., 1996
    windstorm
    Lessons learned from failures of the building envelope in windstorms, by Minor, J. E., 2005
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    O86.1-94 Engineering Design in Wood (Limit States Design), by CSA, 1994
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    Overview of turbulence models applied in CWE-1997, by Murakami, S., 1998
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    Pedestrian wind environment around buildings: literature review and practical examples, by Blocken, B., Carmeliet, J., 2004
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    Review of the need for a large-scale test facility for research on the effects of extreme winds on structures, by Commission on Engineering and Technical Systems (CETS), 1999
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    Ventilation through building walls - wind tunnel studies, by Broasa, P., 1996
    wind and air pressure
    Wind and Air Pressures on the Building Envelope, by Ganguli, U., 1986
    wind daamage of wood house
    Wind damage to wood frame houses: problems, solutions, and research needs, by Liu, H., Saffir, H.S., and Sparks, P.R, 1989
    simple description
    Wind on Buildings, by Dalgliesh, W. A. and D. W. Boyd, 1962
    --------
    Wind resistance of light-frame structures, by Wolfe, R. W., 1998



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