[TowerTalk] Guy anchor distance from tower base?

[David Robbins K1TTT]

Tia-222 can't calculate things like that because those types of calculations
are up to the manufacturer and engineer designing the system.  Manufacturers
like rohn do sets of generic designs for 'standard' installations that
assume flat land, some max wind speed, and specify max wind and weight
loading... but those designs are only for specific tower configurations and
can't cover all circumstances either.  To get a safe design, especially when
you are trying to do something odd like guying a triangular tower to 4
anchors, you must get a qualified engineer to design and approve it.  

That said and noting that I am not a qualified engineer for this type of
stuff... just by geometric considerations you can put a tower closer to
something with 3 guy points than 4, assuming the location of the guy points
are on the setback line and are the same distance from the base of the
tower.  I would not expect the distance out from the base of the tower to
change much for 4 guy points vs 3, it is the distance out that determines
the angle to the tower and the side force exerted... and it is the side
force that keeps the tower upright.  Move the buy points in and they pull
down more than out which does not help keep the tower straight up.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of SJ W3TX
> Sent: Saturday, December 11, 2004 12:15
> To: TowerTalk at contesting.com
> Subject: [TowerTalk] Guy anchor distance from tower base?
> 
> I read the TIA-222 document, but it doesn't specify the recommended
> distance
> between the tower base and guy anchors (as a percent of tower height).  I
> may end up using 4 guy wire directions to allow me to place the tower base
> closer to my setback (so the towers can be further apart).
> 
> What is the standard % for:
> 
> 3 guy wire directions (guys spaced 120 degrees)?
> 
> 4 guy wire directions (guys spaced 90 degrees)?
> 
> 
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> 
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> 
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