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Question regarding wind loading and shielding effects on a structure.

  1. Feb 11, 2009 #1
    I have come unstuck in my coursework project, and cannot find any information/equations for the effects of shielding on wind loading in a structure (This is not an ordinary structure, it is an unsymmetrical sculpture made up of circular and Universal beams).
    So i would firstly like to find how the distance between beams affects the wind loading (the shielding) in the downwind beam - and any further downwind beams-. I need this for circular and non- circular sections.
    Any help on this topic would be greatly appreciated, as there has been many months of fruitless searching.
    Many thanks.
  2. jcsd
  3. Feb 12, 2009 #2


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    I don't know about specific Code guidelines , but I have always in practice not counted on any shielding on the downwind or leeward part of a framed, open structure. For example, if designing say a tall lattice tower for a hurricane load, I take the wind pressure to act on the projected area of one face of the tower, and double it, which is more or less equal to applying the full wind pressure to the projected area of both faces. I believe certain guidelines may allow you to use full wind on the unshielded face, and 1/2 the wind pressure on the other, but the effects of shielding are questionable, especially in your case wher there is not much symmetry, so why fool with it and ignore any shielding reductions. Don't forget the shape factor; on a cylindrical surface, it is 1.0, but on a flat surface, it is 1.6 ; for a hexagonal or octagonal shape or the like, I use 1.3. Thus if the hurricane wind is 25 psf on a round surface, it is 40 psf on a flat surface, and I apply it to all faces normal to the wind, without considering shielding.
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