[TowerTalk] GUYING

[Roger Borowski - K9RB]

Hi Again, Gerald;
I appreciate your taking the time to respond to this controversy. I'm still
having trouble
seeing how, in a 3 point guy system, an adjacent guy is supporting any wind
load
when the wind load is +/- up to 22 degrees off the worst case condition on
the guy
next to it? I still maintain that there is 45 degrees of wind direction per
guy, on a 3
point system where one guy is taking "all" the windload, unlike a 4 point
system,
where this only occurs theoretically for a dead on, worst case 1 degree. At
this point,
we are in agreement that design should take into consideration the worst
case
scenario, that being the same for both examples, but I would really like to
put this
to rest, one way or the other, for my own peace of mind, and possibly that
of any
readers, who are following this or who may care less!  73, -= Roger - K9RB
=-

-----Original Message-----
From: Texas RF <TexasRF@aol.com>
To: wa9eka@worldnet.att.net <wa9eka@worldnet.att.net>
Cc: towertalk@contesting.com <towertalk@contesting.com>
Date: Friday, March 13, 1998 8:15 AM
Subject: Re: [TowerTalk] GUYING


>More on the three way vs four way guying question.
>
>WORST CASE load on the anchor is when the wind blows from the same
direction
>as the anchor (one anchor takes ALL of the wind load). This is the same in
a
>three way or four way guy ststem. By definition, all other wind directions
are
>NOT worst case as the wind load is reduced on a given anchor and increased
on
>the nearest adjacent anchor.
>
>The amount of force on the two adjacent anchors can be determined by
>multiplying the wind force by the cosine of the wind angle relative to the
>anchor angle. This is the case in any guy system, three way or four way.
For
>example, assuming a 1000 pound wind force, in a three way guy system, if
the
>wind is 30 degrees off anchor #1, the cosine of 30 degrees is .866 and the
>force on anchor #1 is 866 pounds. At the same time, the wind force on
anchor
>#2 is cosine of 90 degrees X 1000 lbs which is 707 pounds.
>
>Example #2, same wind force on a four way guy system, anchor #1, cosine 30
>degrees =.866 X 1000= 866 pounds. Anchor #2, cosine 60 degrees=.5 X 1000=
500
>pounds load. In this case the load on anchor #2 is less than in a three way
>system but the load is trivial compared to the design strength of the
anchor.
>
>If you were to plot out the loads on the anchors on a piece of graph paper
you
>would see the shape of the plot to be the familiar sine wave that we
encounter
>so many times in our study of electronics theory. In the anchor case, the
>curve is shifted 90 degrees (that is why it is a cosine function). You will
>recall that the curve is somewhat broad on top and falls rapidly down the
>sides as you go through the various angles from 0 to 90 degrees. The forces
on
>the anchors also follow the same shaped curve.
>
>Anchor forces are essentially the same in a three way or four way system.
You
>still have to design the anchor for the same worst case loads. Any given
>anchor will be "loafing" when the wind is blowing in the opposite direction
>plus and minus 90 degrees to the anchor. This is the same for a three way
or
>four way system. In either system the wind load is never applyed to more
than
>two anchors at any given time as all other anchors are in their "loaf"
zone.
>
>Hope this is of interest to some and helps clarify the three way versus
four
>way guy question.
>
>Tnx/73 de Gerald, K5GW



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