On 4/13/2014 1:56 PM, Gary Schafer wrote:
Roger,
"My thoughts" which I'm afraid will be a bit wordy! <:-))
J-Bolts, or the properly sized and threaded rod for the largest future
tower that could be installed "should work" IF that configuration meets
the future tower's specs including the number and placement of the rods.
You might find the half inch plate to be a bit on the light side.
I think you will find that welding the ends of the ears to the plate Vs
welding the length to the rod may require some adjustments in size and
welding approach. You can't just stand the ears on the plate and weld.
The entire contact area has to be welded which requires tapering the end
of the ears so the weld starts at the center and is layered out to the
edge. The finished appearance should "look like" the ear were stuck on
the plate and a neat weld were made around the periphery. A certified
welder would have no problem layering it up to the desired, final
appearance (with no voids), but an engineer has to tell him what area of
weld and what it's welded to is acceptable.
This is the highest stressed area for the entire tower installation. Get
a qualified engineer to go over the base to make sure it's strong enough
for present and future plans.
Modifying the base is no simple task. "It should be OK if it matches
future and present designs for the same or larger towers
It's not me, but were it me, I'd find a competent engineer to go over
the plans and welding needed/acceptable as well as all other fasteners.
It sounds like a good approach, but I'm not an engineer.
Good luck.
73,
Roger (K8RI)
I have one of those towers to put up one day too. I was thinking rather than
weld the ears to the large rod as the factory shows, using threaded rods
coming out of the concrete and using a 1/2 inch plate to bolt the rods to.
Then welding the ears on the plate that then bolt to the tower.
That way I could easily use the foundation for a different tower if I wanted
to change to something else.
The threaded rods also make for easy leveling of the tower.
What is your opinion of that?
Thanks
Gary K4FMX
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Roger (K8RI) on TT
Sent: Sunday, April 13, 2014 2:46 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Welding Rebar
On 4/13/2014 1:47 AM, Brian Amos wrote:
If you weld it the rod may rust which will cause the concrete to
burst.
Rusting requires an oxidation source. Rod protruding from the concrete,
or flux. I'm using Metal, Inert Gas or MIG for short. I'd not want to
use stick welding. These are "tack welds, not true welds. They are just
enough with what wiring I can do with one hand, that I'm not worried
about the cage changing shape before we pour the concrete. The "twist"
is much like we use on aircraft nuts and bolts, except we are using soft
iron and not #20 or 24 SS.
I'm used to sticking the two ends into a tool, pulling a handle that
reminds me of a Ty-Wrap tool. Just about instant twist.
The Iron wire is large enough , #14 I think, that it can be twisted with
regular pliers.
Tack welds are small enough that I'm not worried about changes in
strength.
There are 3 major welds. Those are ones holding the 1/2" X 3" X 25" ears
to the #10 rerod The tower and raising fixture bolted directly to
these.
If we could get the rerod to stay in place we wouldn't need to fasten
it. The rod just serves as a reinforcement for the concrete, although
with the LM470 the big stuff that holds the tower is part of the cage.
I like the idea of everything connected as it serves as a very good UFER
ground. Course that connects to a network of over 600 feet of bare #2
that is cad welded to 32 or 33 8' ground rods.
Speaking of grounds. I've lost 2 of the big Diamond dual band (144/440)
antennas. I think I've lost a system ground in the shop and it went to
ground through the antenna.
73
Roger (K8RI)
Not
a fun situation as usually the recommended repair is completely remove
the
foundation and replace it. As a foundation engineer I only hear the
failures and what the standard of practice and code say, so maybe it
has
worked under the right circumstances. If it has an issue and it was
not
built to code the insurance company will not cover you.
Tying rebar is not fun and can be hard work but stout teenage boys
will
learn quickly and work for a small portion of what a concrete company
would
charge. I usually offer a favorite meal ajdand tgat is ebough. You
may
even find some free and experienced help from your ham club. I know
whenever someone in my club needs help with something that falls
within my
line of work I am more than willing to lend a hand.
Brian
KF7OVD
On Apr 12, 2014 10:42 PM, "Edwin Karl" <edk0kl@centurytel.net> wrote:
Roger,
As part of my mis-spent youth I was an iron worker, worked at it for
about
6 years.
We were referred to as "rod busters" by some. In any event installed
lots
of iron
in the new York area.
Now that I'm retired, I built my own home, not with my hands, but was
the
general
contractor. You can do that in the country ... I did do the
reinforcing
myself; so my
driveway, sidewalks, patio, basement walls and floor all have steel
internally. The
also barn has a reinforced concrete floor.
The tower is an AN Wireless 90 footer with a big foundation, rear 3
layers, top bottom
and middle is about 12 feet deep, took 21 yards of concrete to fill
the
hole. There is a
section of tower made to go in the foundation which splices to the
rear.
Now I'm saying all this because of a decision I made years ago, if I
had
the chance, this is
how I would choose to build my own home, etc. It might be nit picking
but
the issue with me
probably pertains more to structural iron, like the tower etc. Don't
do
anything like welding
which may change the characteristics of the iron negatively. Also
affects
galvanizing etc.
Probably way over thinking the issue, which I usually do.
I also will confess in my day, except where cad welding 1 1/4 rear
for
power houses etc,
never saw rear welded. Generally a splice is 20 times the diameter
side by
side and double
tied.Compared to structural, rear is soft, we would bend it on site
for
hooks and angles, so I
suspect it's already not too stuff. But as I said initially the bar
reinforces the concrete, which
holds the bar in place.
Sorry for being so lengthy ... but, if there are other issues as you
mention than explain why welding
might be acceptable. We would take columns and beams using wire to
kind of
guy it internally, if
the item has a long way to go or was a difficult pick for the crane
etc.
If you are having the job
fabricated off site it probably could be done either way, if you're
alone
tack welding could work.
I wish you well, and would appreciate hearing from you as the project
progresses.
By the way, 8 or 9 inch lineman's pliers and end cutting nippers are
tools
of the trade, The nippers
work real well when tightening the connection, After a few mistakes,
you
can get the hang of it.
Very 73!
ed K0KL
On 4/12/2014 9:37 PM, Roger (K8RI) on TT wrote:
On 1/5/2014 12:58 AM, Roger (K8RI) on TT wrote:
On 1/4/2014 4:01 PM, Ed K0KL wrote:
I can't stand it any longer ...
And the problem is?
If wired in place or near the hole they work fine. If shipped, or
handled
a lot they seem to come already welded.
As I only have one useful hand, tack welding is faster, easier, and
makes
for a far more secure joint than wiring one with just one hand.
I noted when at my steel supplier, they had a cage, mostly done that
was
all welded. The customer would put it on a trailer, haul it 10
miles or so
and then stick it in the hole with the same dimensions as when he
picked it
up.
73
Roger (K8RI)
Wire ties are fine to keep the rebar touching from bar to band
(the
smaller rod surrounding the
verticals or horizontals as it were). It has been used for years
on
buildings, roadways, etc. Generally
speaking the concrete holds the connection together, the
connection and
rod make the concrete
strong ...
Order towers with the rebar cage and they likely will come welded
and
not tied.
That's been the local experience.
73
Roger (K8RI)
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