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[TowerTalk] Guy Anchor Pullout Strength

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Subject: [TowerTalk] Guy Anchor Pullout Strength
From: (
Date: Wed, 1 Jul 1998 10:50:35 EDT
In a message dated 98-07-01 09:58:30 EDT, writes:

> Per my 1991 ROHN catalog, for 110 mph basic wind (no ice) your 110 ft of 25G
>  isn't even on the charts!  100 ft of 25G @ 110 mph wind requires 80% guying
>  and will take only 7.4 sq ft load.

     Actually York county is only an 85 MPH windspeed zone but it is within
100 miles of hurricane oceanline so I think that the 110 feet and 8 sq.ft. of
wind loading is reasonable. I don't discourage anyone from over-enginering
their installation. 

     An obviously better steel choice is Rohn 45G. A much better investment
for this scenario. 
>  Even the 90 mph wind no ice 110 ft of 25G tower specs out at 80% guying.
>  Your 45.5% (50/110) guying design is way too low and will result in a very
>  unstable installation (my opinion).  For example, I use 93% in  my design.
>  The higher the % guying, the more stable the design.  I've heard that the 
> rule
>  of thumb is no less than 60% guying.  

      Yes, 80% for guy anchors is ONE scenario. Pirod Towers uses 70% for
their specs. Yes, 93% does reduce some of the system stresses. But many things
are possible IF you get an engineer involved to design and calc everything.
The 45% guying is highly suspect without the aforementioned professional
intervention. DO NOT hip-pocket engineer something like this.

Cheers,  Steve   K7LXC

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