K7LXC@aol.com wrote:
> I'm not a fan either. My statement was based on the fact that if one is
> rated at 2500 lbs., then two must be rated somewhere around 5000 lbs. Since
> 3'16" EHS has a breaking strength of 4000 lbs., that might be in the range of
> the capability of two properly installed screw-in anchors.
>
> Or not.
I agree with you about following the manufacturer's recommendations;
I'm basically willing to trust what ROHN puts in their book It's been
awhile since I was putting up towers for others and haven't looked at
a ROHN book since then, but I don't remember seeing two screw
anchors used together. They would have to be spaced such that the
volume of soil affected by the individual anchors do not overlap.
If spaced apart so they are both the same distance from the tower, then
some means must be used to split the load between them without pulling
off the axis of the rod; otherwise part of the holding power is used in a
direction which is not in the direction of the tower. In fact, the load may
even be distributed unequally on the surface of the screw plate, greatly
weakening the system.
Properly installed in the proper kind of soil they may have their
applications, but I guess I'm just a worry wart. I wouldn't use
them for long term use.
The early bird gets the worm, but the second mouse gets
the cheese.
Cheers.
Lyn, W4WDN
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