[TowerTalk] Anchor Bolts

[Roger (K8RI) on TT]

I mean no disrespect to any one, but I get a queasy feeling any time I 
see engineers making changes that require improvisation, be it 
mechanical, electrical, or chemical.

I worked in the chemical industry from a technician to a degreed CS 
professional..  I've seen some pretty spectacular mistakes be engineers 
and project managers in all of these fields.  Fortunately no one was 
killed, but some were pretty well banged up, including one guy blown 
through a blow out panel and traveled another good 60 feet.  I've seen 
grounding straps vaporized with enough force to bend 7 foot tall X 3 ft 
wide steel doors of 1/8th thick steel with 2" shoulders and rolled edges 
to bend those doors 2 feet in the center and it was loud.  I've seen 
people go flying after chemical residue detonated, but that stuff was 
all proprietary.  All I can say I saw it, it was spectacular, and no one 
was killed.

That no one was killed or seriously injured was most likely due to the 
stringent safety regulations and protocols we had to follow. There were 
some short hospital stays, damaged hearing, and a couple cases of 
extreme nerves.  I actually felt safer as a tech working with the stuff 
than a guy with a degree that had to be around it.

As hams, be it climbing, or construction, no one "forces" us to follow 
the rules.  We can wing it, or best guess, but often we'd do better to 
ask a professional.

Were it me, "and it's not":  First, I'd make sure the holes were deep 
enough to provide the required holding strength.  The larger the hole in 
the base material, the weaker the holding strength, even with bushings.  
"IF and I emphasize the "IF" the amount and depth of the base material 
is sufficient for strength, AND the concrete mix is strong enough 
(depends on concrete, water, and aggregate ratio as well as cure)  I'd 
make, or have made some sufficiently long threaded bushings to provide 
the desired clearance.  I would present these figures to a construction 
engineer for his blessings.  I'd have sufficient confidence in my metal 
work, but would seek outside qualified help for the concrete and holes.  
As long as we have bushings, I'd weld the bottom end of the bolt into 
the bushing.

Those holes have to be a depth to provide the required strength with 
that diameter hole!  THEN the epoxy has to be strong enough with the 
required clearance in a hole that big.

73 and good luck,

Roger (K8RI)