>
> One thing. DON'T even think about back filling the hole with concrete to
get it back up to grade. The base pin and plate is a far better way to do
it than the typical Hammy Hambone method of burying the bottom section of
tower in the concrete. You want the tower to be able to sway and give a
little under high wind conditions.
The base of any tower DOES NOT sway. And with a properly tensioned guy
system, there is very little movement anywhere in the tower. I mean you've
got at minimum 1200 pounds of tension on one guy level (3/16" tensioned to
10% spec or approximately 400# per guy times 3 = 1200#). It ain't going
anywhere.
> Fixing the base solidly in the pier buried under concrete causes
movement of the tower under wind conditions to put all the stress on the tower
sections, possibly causing failure at the welds under extreme conditions.
I'm not an engineer but I can't find any validity in this
statement. Bigger towers use the pier-and-pin technique because it minimizes
leg
stresses on big towers with microwave dishes which are kind of a non-issue
for your typical amateur installation. There are tens of thousands of guyed
towers with the bottom section buried in concrete and the incidence of that
failure mode is non-existent in my experience.
> Besides, back filling with concrete would be no guarantee of a perfect
seal between the old and new concrete, and any additional rust would then
be hidden from view - not good.
Wrong again. The seal is immaterial. A big plus is that the
questionable legs will be entombed in concrete with zero chance of failure.
It'll
also put the top of the base above grade so that this situation will never
happen again since water will just run off.
Cheers,
Steve K7LXC
TOWER TECH
Have worked on over 250 ham installations and dozens of commercial sites
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