On 11/18/22 6:51 AM, Lux, Jim wrote:
On 11/17/22 9:51 PM, KD7JYK DM09 wrote:
On 11/17/2022 18:33, Hans Hammarquist via TowerTalk wrote:
I used the same type as the utility companies. They are a lot cheaper
if you buy them from a utility supply house. Anyhow I put them in
with the hep of a sledgehammer and a break-iron. We were two to do
it. You turn the helix anchor as far as you can. then you hit it a
few times with the sledgehammer and continue turning. The idea is
that the screw-anchor should be set in "undisturbed soil" to get
maximum strength.
I looked at those when I was buying the utility pole thimble eyes.
My concern was, despite that big elaborate screw, depending on the
model, there was a few tack welds, or one relative short weld around
the shaft to hold it.
Crack that, and the anchor slips out, leaving the screw in the hole,
and tower on the ground.
All the screw in anchors I've seen (several dozen, 30 years ago) had a
continuous weld for the entire helix. I would say that a "tack weld +
short weld" is a unit that was mis-manufactured (i.e. shipped before
the final welds were done). As you say, if the weld were to fail it
would be a problem.
I guess it's possible that as long as the total weld area is
sufficient (greater than the shaft cross section), the screw might
deform, but still stay attached and mostly embedded (the helix pitch
might get longer or it might unscrew a bit (sliding along the helix
length), but that seems unlikely, since the soil is holding it in
place. It's all one piece of metal (if the weld was done properly). A
good weld won't be more brittle than the parent metal.
They do actually test these things - Ask the mfr if that's their
standard practice.
Here's some literature from Hubbell - Chance that shows their anchors.
These have several single helices on the same shaft.
https://hubbellcdn.com/literature/SF04215E_0419%20New%20Construction%20Helical%20Foundations_WEB.pdf
Another vendor (ECP) has a similar design
https://ecputility.com/hta3-12round/
More info from Ideal:
https://www.idealfoundationsystems.com/helical-piles/
The anchors in the above links are installed by a hydraulically driven
system - We called a company that does the installation - that's what
they do, "install anchors" for utility poles, holding up towers,
supporting concrete tilt ups, etc. They'll also come out and "unscrew"
it to remove it, as well.
If you're talking about something like this
https://gemplers.com/products/auger-style-anchor
I don't know about that.. these are rated with pretty low loads (2800
lb) and the helix is only 10ga material.
heck, in the photos you can *see* that there isn't a continuous weld.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|