[TowerTalk] Tower Anchor Bolt source

[Jim Thomson]

Date: Thu, 29 Nov 2018 17:29:40 -0500
From: Howard Hoyt <hhoyt at mebtel.net>
To: towertalk at contesting.com
Subject: [TowerTalk] Tower Anchor Bolt source

<Hi TTBrain,

<I would appreciate leads to good sources for 1-1/8" x 27" tower anchor 
<bolts.

<Cheers & 73,
<Howie / WA4PSC

##  Tower anchor bolts  are  NOT the place to cut corners !   The only thing that is
securing my  5600 lb  HDX-689 ...which includes mast, both bearings,   PP rotor,
and ants  to the    7 x 7 x 9 ft deep  base.... are the 12  anchor rods.   4  per corner. 

##  Tower bolts to the 600 lb steel base, which in turn  is anchored to the concrete 
via the  12  anchor rods.   Total weight, including the  steel base is  6200 lbs.  This
does not include the weight of the 12  x anchor rods. 

##  UST specified   1.125 diam x 36 inch long  anchor rods, and  36 ksi  strength . 
There is  6 inches of threaded  rod sticking up out of the concrete.  That only leaves 
30 inches below the concrete...which seems  silly, when used in conjunction with a 
9 ft deep hole.  With 4 inches of concrete  above the lawn, that now only leaves  26 inches 
of anchor rod below ground level.     I bought the 12 anchor rods from Portland Bolt, in  Ore.   But I
specified them  to be 60 inches long, and   105 ksi yield  strength.   Anchor  rods come
in 3 available strengths.   36,   55, and 105 ksi.  They are also color coded on the very ends,
blue is  36 ksi,   green is 55 ksi..and red is 105 ksi.   I had them cut  6 inches  of thread on each
end of each of the 12  rods. 

##  Horizontal   60 ksi yield strength  15mm rebar used, with stirups on one corner.  Horz rebars
are spaced  every  6 inches  down to the bottoms of the anchor rods, then Horz rebars are spaced 
every  12 inches..to bottom of hole.     24 x 25mm  diam Vert  rebars used, also 60 ksi,  evenly spaced around the perimeter. 
In my case, thats  9 inches  inside to inside, between  adjacent   vert rebars.    

##  To increase the pull out capacity,   I had the local metal shop fabricate  three  9 inch  x 9 inch 
x .375 inch thick steel plates, with  4  x  1.250 holes punched for the anchor rods.   One 9x9
plate onto the bottom of each group of  4 x anchor rods.    If only  2 anchor rods are used on each
corner, then  rectangular plates  are used.   I cold galvanized the 3 x plates b4 installing them. 

##  Anchor rods into concrete is a one shot deal.   You dont get a 2nd chance to get it right.   In my case,
being in a residential area, and also a seismic zone, thats the hoops I had to go through, to get approved,and
signed off by local engineer. 

Jim  VE7RF