[TowerTalk] ROHN tower anchor question

[Pete Smith]

At 06:16 PM 7/29/00 -0500, Mark wrote:
...
>ROHN that states "The soil is cohesive with an allowable net vertical
>bearing capacity of 4000 pounds per sq. ft.(psf) and allowable net
>horizontal pressure of 400 psf per lineal foot of depth to a maximum of 4000
>psf."

The exact calculations are well beyond my capabilities, but an engineer
once explained it (on the old CQ-Contest reflector, I think) as a function
of the characteristics of the soil, the depth at which the anchor is
buried, and the angle of the guy wire's pull.  Essentially, the anchor
drags along with it a mass of soil dependent on all those variables, which
accounts for the additional capacity.

One of my guy anchors lies in a field that every few years goes under water
temporarily in the spring.  At that point, I'm VERY glad that anchor is
downwind in the prevailing conditions, because I assume its capabilities
are seriously compromised when the soil above the anchor turns to soup.  On
the other hand, I'm even gladder that it's not a screw anchor, which have
next to no inherent anchoring capability (other than the soil they are
screwed into).  At least the concrete anchors have some mass...

73, Pete Smith N4ZR

The World Contest Station Database 
is back up and running at
http://www.qsl.net/n4zr 



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