In a message dated 5/27/01 4:32:24 AM Pacific Daylight Time,
k9nupaul@udnet.net writes:
> I lost my US Tower TX455 this week. It had been up for 9 years and had a
> 4 element Lightening bolt quad (about 13 sq. ft) and a Big Boy PST61 on
> it. All is trashed except of the rotator. The bolt that failed appeared
> to have had some damage for some time. It snapped about 1 1/2" above the
> concrete pad and about 1/2 of thread into one of the nuts that is used
> to level the T mounting bracket. About 2/3 of the diameter was
> discolored. I guess the wind on Monday exerted just enough force on the
> remaining 1/3 of good "meat" to snap it. Fortunately, the tower fell in
> an open area of the back yard and no one was around. It could have been
> worse. Has anyone experienced this type of bolt failure?
It's not uncommon with bolts exposed to the weather - they oxidize and
rust away. US Tower specs (and specs for any anchor bolt tower for that
matter) specify non-shrink grout to fill in the void between the bottom of
the base fixture and the top of the concrete pad. The grout keeps the wx out
and also becomes part of the weight-bearing base.
Raise your hand if you who put in non-shrink grout under your crank-up.
Hmm, not very many hands went up.
>
> I'd also like to know if there is a safe method of installing new anchor
> bolts in to my existing pad. At this point, I plan to have the pad
> removed of bury it.
Piece of cake. Re-orient the base fixture on the concrete base after
chopping off the remaining bolts with a grinder and rent a concrete
drill/corer to drill holes for new anchor bolts. You can use rock expansion
bolts, industrial expoxy or both to bond the anchor bolts to the concrete
(this is done every day in industrial projects).
Cheers, Steve K7LXC
Tower Tech
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