[TowerTalk] Pipe for guy anchor

[Grant Saviers]

There are two forces - the preload which is often specified at 10% of 
guy break strength and the maximum force from wind, which might be as 
much as 80% of the specified guy break strength.  (rough estimates). 
The former causes a slow tilt and the latter might be catastrophic.

I beam (now mostly WF or Wide Flange) and schedule 80 pipe have been 
suggested, both of which might be harder to find than other structural 
steel sections in less than 20ft lengths.  If you need 3 posts then 20ft 
might make sense and have them cut at a steel service center which 
should have whatever section you might want. Square tube is another 
which I have found more available at retail steel distributors, say 
4x4x3/8. All reasonable choices are pretty heavy in 8ft lengths.

Engineers edge provides the tools for calculating the deflection and 
stress for a simple cantilever once you find the steel section 
properties in various tables.

However, this is really PE territory re strength and needed foundation. 
  A back guy is also a very good idea to prevent slow tilt.  ie 600# x 
45deg pretension (.7) x 6ft = ~2500ft-lbs of torque at ground level 
slowly working to tilt the concrete base.

Grant KZ1W

On 8/9/2022 05:34, Rick Harrington N0VT wrote:
> I have a small lot and my tower is 70' of 25G.  Due to some obstacles in 
> the yard that can't be worked around I need to sink some metal pipe in 
> concrete and attach the guys about 6 feet up instead of taking them down 
> to the ground.  I realize this isn't the preferred situation.
> 
> What type of pipe should I be looking for?
> 
> Thanks, Rick N0VT
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