In a message dated 98-06-14 11:50:43 EDT, ROBKEL@aol.com writes:
> The US tower design appears to use about 5 ft long 'J' bolts, as did my
> current Heights tower. A large Andrew Earth Station Dish bolts are only
> deep for about the same OTM. The Hilti epoxy design is also about 18" for a
> 1.25" bolt (which has only about 30,000 lbs working, 110,000 lbs Ultimate,
> 2000 psi concrete).
> The reason I am asking is this will govern how much of the old base has to
> removed to allow a good installation over it.
I would NOT remove any of the existing base. Rent a concrete corer and
drill the concrete where you want the new anchor bolts to go. Get the
appropriately sized thread stock with the proper strength rating and epoxy
them in the holes. Check the yellow pages and call an industrial supplier the
the epoxy. (I could even get it at my local True Value hardware store.) The
coring bits will drill right through rebar. This technique is used all the
time for commercial installations.
I don't have the answer to your "how much depth" question.
Cheers, Steve K7LXC
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