Hi Bill,
With"stiffness" I mean how much the tower will move for a specific wind
pressure. In my calculations I assumed that the tower moved 1" for a give
wind. Then I calculated how much the tower moved for the same wind force with
different guy anchor point. I found that minimum move was for an anchor
distance of ~142%. (probably sqr(2)) under the assumption of no guy wire sag
(which is impossible).
I was just "playing around" with a spread sheet and was interested to see
where the optimum point was. 0% anchor point is no good for obvious reason
but an anchor point very far away is not good either as the guy wire is
springy and a too long wire will allow the tower to sway in the wind.
That's when I saw how much less critical the angle is between the wires
when you are using four guy wires instead of three.
Hans - N2JFS
In a message dated 10/6/2011 3:57:02 P.M. Eastern Daylight Time,
baycock2@centurytel.net writes:
When anyone uses the words "stiffness" and "optimum", I want to ask
"Stiffness of what?" and "With respect to what criteria?"
Also- what type of tower? Why Utility and not EHS?
Bill--W4BSG
On 10/1/2011 10:17 PM, _HansLG@aol.com_ (mailto:HansLG@aol.com) wrote:
Hi Dorn,
I made some calculations regarding guy wires some time ago. One thing I
found out was that you gain some stiffness by mowing the guy anchor out
some.
Not considering the sag, the optimum anchor point is about 140%. If you
include sag you probably have to decrease that a little. I also noted that
it
is a lot easier to use four guy wires instead of three. The position of
the
angle is much less critical.
I use 5/16" (11,400#) utility grade wire for my guys which was a lot
easier to work with than expected. You can check it out at
__http://www.facebook.com/media/set/?set=a.10150198503693539.328964.57975353
8&l=1c649b80ab&type=1__
(http://www.facebook.com/media/set/?set=a.10150198503693539.328964.579753538&l=1c649b80ab&type=1_)
(_http://www.facebook.com/media/set/?set=a.10150198503693539.328964.57975353
8&_
(http://www.facebook.com/media/set/?set=a.10150198503693539.328964.579753538&;)
l=1c649b80ab&type=1)
73 de,
Hans - N2JFS
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