Well, there are beam bending formulas for distributed loading... the
windload of the structure itself is nonnegligible, but it's a simple
beam so it's straightforward to analyze. Take the formula for
windloading of a cylinder like you'd calculate for a yagi boom or
something... calculate the total windload on the 10 inch 100 foot tall
cylinder (proportional to (wind speed)^2 * frontal area), and divide
by 100 feet. This gives you a distributed load in pounds per foot.
Then calculate the total windload of the antenna system in pounds for
the wind speed you're looking at, and add that as a point load at the
end of your cantilevered beam.
Beam bending formulas:
http://www.engineersedge.com/beam_bending/beam_bending8.htm (distributed load)
http://www.engineersedge.com/beam_bending/beam_bending9.htm (point load)
Superposition applies, so you can calculate the two stresses
individually and add them. Then you need to make sure that none of
the stresses exceed the yield stress of the materials involved.
Calculate at your own risk! Use a healthy safety factor!
TowerTalk mailing list