Date: Sun, 15 Apr 2012 13:49:41 -0400 (EDT)
From: K7LXC@aol.com
Subject: Re: [TowerTalk] Anchor bolts for LM470
> There is no need and it is not recommended by American Concrete
Institution
(ACI) 318 design specifications for reinforced concrete to use hooked (J)
anchor rods in tension situations without reducing the tension capacity
significantly for hooked anchors on account of the crushing of the concrete
at the bend radius.
Interesting. I didn't know that. That's probably why they don't come
like that anymore.
You should do what UST does and put 2 big nuts on the concrete end and
voila! - a factory-esque anchor bolt. I don't think you have to weld them
in place - just tighten them up. They ain't going anywhere.
Cheers,
Steve K7LXC
TOWER TECH
## The tower in the various pix of the TX-472 only depicts ONE anchor rod
per corner. Anchor rods are not like rebar, they have no ribs on em. Why mess
with double nuts. You may as well insert a single 4 inch square plate
between the
double nuts, then crank em super tight, like 200 ft lbs. Then no need to weld
anything.
Then you can really put the double nuts to some real use.
## On towers with 2 or more anchor rods per corner, I’d suggest a plate
between the
2 or more anchor rods. Portland bolt even makes and sells the plates, with
whatever hole
spacing you want.
## In my case, the UST- HDX689 uses 4 x anchor rods per corner, on 5” center
to center
spacing, in a grid format. My local engineer suggested using a 50 mm washer
between 2 x nuts
on the bottom of each of the 12 x anchor rods. I pointed out to him that the
massive nuts used
on the 1.125 inch rods were like 52mm corner to corner! He then suggest
using 4 inch od washers.
I then tell him that wont work cuz the bolts are on 5 inch C to C spacings. I
had a better idea, and that
was to get 3 x plates sheared. Each plate is 9 inch square x .375 inch thick.
I had the metal place
punch 4 x 1.25 inch holes in each plate. I sprayed them with several coats of
that zinc spray.
## 8 x nuts used per plate. The resulting uplift pull out capacity is
through the stratosphere.
The 105 ksi strength rods hardly cost anymore than the 55 ksi variety.
Order them galvanized
from Portland bolt... + the mating heavy duty galvanized nuts. 36 ksi rods
can’t be used here
anymore.
Jim VE7RF
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