[TowerTalk] Guy Strain

[Kurt Andress]

c penna wrote:
> 
> Hi
> I wonder there is a formula for converting guy strain at a given guy angle
> WRT ground to another angle. ie if a guy has a Max strain of say 1000lbs @
> 60 deg angle WRT ground what would it be at 50 degrees?. I have lowered the
> guy angle of my tower top guys and I'm interested to see what has happened
> to the guy strain if anything. Can anyone confirm also that the maximum
> strain in a guy should be 10% of the breaking strain or is that a bit too
> conservative.
> 73 Clive GM3POI
> 

Clive,

While mathematically correct answers have been presented, some
additional comments are in order.


"Strain" is the measurement of "the per unit length elongation in a
material under load." Since, most materials exhibit elastic behavior
under load, they elongate and Strain is its measurement.

It's probably best to talk about the "Load" in the guy cable. 

Taking your example:

With a 60 degree angle between an assumed straight guy wire and flat
horizontal ground (we'll call this angle Theta), and the load is
directly
aligned with the guy under consideration.

We'll assign a value to the horizontal load at the tower/guy connection
as 1 unit. (Lb, Slug, Kg, Newton, etc)

The load in the cable (assuming no contribution from the tower) is:

Cable Load L = 1 (Unit)/ Cosine (Theta) = 1/cos 60 = 2.00 Units

Moving the guy anchor out to achieve a guy/ground angle 50 deg produces:
1/cos 50 = 1.55 Units

The change results in a ~22% decrease in cable load.

-- 
73, Kurt, K7NV 

Visit http://www.freeyellow.com/members3/yagistress/

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