[TowerTalk] Anchor bolts for LM470

[Jim Thomson]

Date: Sun, 15 Apr 2012 13:49:41 -0400 (EDT)
From: K7LXC at 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