Ahh, so now it comes out you are using a solid steel rod as a substitute for
stranded EHS galvanized guy wire.
More smoke and mirrors.
What kind of steel??
Where are the insulators and other hardware you'd need to eliminate
resonances?
...and exactly how much stretch are we talking about under how much load?
This would be a much more useful comparison to demonstrate if it's even a
concern at all (which I seriously doubt). If one stretches 1/8"
per 100 feet per 10000 lbs of tensile load while the other stretches
1/2"....who cares??? The tower sure wont.
Then we can go back to comparing similar tensile strength materials and
realize "Hey, 3/8" diameter fiberglass rod IS a lot lighter than 5/16" EHS guy
cable...even without the extra insulators, grips, etc"
Please do us all a favor...
Get your nose out of the textbook and into the real world.
Compare actual products in realistic terms and applications.
Until then, please stop misleading everyone on this reflector.
73, Ty K3MM
-----Original Message-----
From: Mark, N1LO <n1lo@hotmail.com>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Friday, March 19, 1999 21:32
Subject: RE:[TowerTalk] Fiberglass Guy Rods- correction
>
>Oops, let me make a clarification on the elasticity comparison:
>
> I failed to include that the relative elasticities among the materials
>is for the same cross-sectional area! Sorry for the confusion.
>
>It is possible to have equivalent stretch between steel and fiberglass
>guy materials if the fiberglass rod is oversized.
>
>Compared to a solid, 0.25" diameter steel rod, a fiberglass rod of the
>properties previously mentioned would have to be about 0.25 x 2.2 = 0.55
>in diameter to have the same deflection rate (spring rate)along its
>length.
>
> The cross sectional area of the fiberglass rod in this case would then
>be about 2.2 squared = 4.8 times that of the equivalent steel rod.
>
>The breaking strength of this fiberglass rod would then be about 28,500
>lb, based on the strength of 120,000 lb/sq in given before.
>
> Based on the densities of 0.282 lb/cu in for steel and 0.073 lb/cu in
>as previously reported for the fiberglass, the weight per unit foot of
>the fiberglass works out to be about 1.25 times that of the steel.
>
>Since the fiberglass is a little stiffer, yet heavier per unit length, I
>would guess that the sag would be close to or only slightly less than
>the steel.
>
>The point is, you *do* have to look at the 'stretchiness' of the guy
>materials. The more 'stretchy' they are (low modulus), the more
>oversized they must be for the equivalent stabilizing effect on your
>tower.
>
>FWIW,
>
>--...MARK_N1LO...--
>
>
>
>Get Your Private, Free Email at http://www.hotmail.com
>
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