I agree it would be better to use the existing anchors and make an
adapter plate. Drilling new holes, deep enough, with unknown rebar
locations, and precise enough locations will be challenging. You can
rent the biggest hammer drill but the bits will cost $100+ ea. Hit
enough rebar and you will need more than one bit. Drilling truly
vertical and in position will be difficult. Epxoy anchoring is easy
with a clean hole and anchor, see the Simpson Strong Tie catalog for a
gun, 2 part anchoring epoxy, and self mixing nozzles. Costs - drill
rental $50, 2 bits $250, epoxy gun $75, epoxy $60, anchors $100 = > $500
Here are the 589 base dimensions - you have the anchors in place so know
the T dimensions
The T is 1/2 x 8" plate, I can't tell if the cross to the vertical is
butt welded or if it is cut to a T ;-). If UST were making a batch, a
waterjet job of parts nested on a 4x8' sheet might be the way to go.
The two forward (hinge) bolt areas are doubled with a 1/2x9x9"
reinforcement plate edge welded all around
the vertical of the T is reinforced on top with two 2x1" channels about
2" apart and skip welded, open on the ends for HDG Zn drainage. I think
these are there for the raising fixture stresses, not important
otherwise, given how close the base flanges are to the anchor bolts. Or
perhaps the T is butt welded and these were welded on first to keep the
T flat, a good idea (underneath) if you weld up the T.
the base to tower leg angles are 4x4x1/2 x 15" drilled 7/8 for the leg
bolts (A325 )
the base bolts are 1 1/8, 6x
I think a 3/8" thick T will do for a 55' tower, it is what I have seen
on them. costs: 10' of 3/8 x 8" A36 HRS $110, you probably don't need
the channel with the base you have bolted onto the new T,
welding/shearing/punching $200?
Nothing very hard about this for a fab shop except you measuring and
them punching the holes (maybe 1 1/4" diameter for the existing
anchors) in the right places.
Others have coveraged HDG vs paint, I didn't grout my 589 bases after I
saw what it did to a base galvanizing of another UST. Just keep the
underneath clean of debris.
Grant KZ1W
On 8/14/2015 9:43 AM, Jim Lux wrote:
On 8/14/15 6:54 AM, Russ Dearmore via TowerTalk wrote:
Andre, I would avoid using anchors as the bolts are much more
reliable and stronger. If they were even remotely adequate I'm sure
the tower companies would recommend them but instead they go with
long anchor bolts. An adapter plate would be pretty easy to make (or
have made) and the peace of mind would be well worth it. Good luck
and 73's.... Russ K5ZZR My Heroes Wear Combat Boots!
Chemical anchors are typically stronger than the underlying concrete
(that is, if it fails, it pulls out a cone of concrete with the anchor)
Tower companies recommend what's easy, and people were casting long
bolts into concrete for decades before chemical anchors were invented.
Chemical anchors require drilling a hole, cleaning the hole, then
installing the anchor. They're the ideal solution where you're not
sure where the anchors need to be, or when doing retrofits.
Put your mind in the place of a tower company selling to hams, most of
whom will do ONE foundation and tower in their life. long bolt cast
into concrete is easy, there are pictures in the handbook, their
Elmer, who put up a tower 30 years earlier probably did it that way, etc.
It's the "low hassle" way of doing things.
But when it comes to "build adapter" or "install chemical anchor" it
really depends on the individual situation, and what kind of tools and
facilities you have. Some people have slabs of 1/2" steel and a big
drill/plasma cutter/welding equipment available. Others don't.
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