[TowerTalk] Welding Rebar

Sun Apr 13 02:29:19 EDT 2014

I pretty much agree with these comments.  There seems to be a perception 
among some folks that a welded rebar cage is stronger than a tied one.  
I don't believe that to be necessarily true, and about the only 
advantage I can think of for a welded cage is that it would hold 
together better if it was built somewhere else and moved to the hole.  
For assembly on site, the use of hooks and properly overlapped/tied 
joints (the 20 times thickness mentioned below) meets every code that 
I'm aware of and correlate with the physical mechanisms involved.  Given 
the varied and uncertain metallurgy of common rebar (weld-rated rebar is 
considerably more expensive) I can imagine more jeopardy from welding 
the cage than benefit.

Tying is trivially easy anyway.  I can make a secure tie in less than 
five seconds using the wire ties that have the loops on the end and the 
cheap tool with the rotating hook.

73,
Dave   AB7E

On 4/12/2014 10:47 PM, Brian Amos wrote:
> If you weld it the rod may rust which will cause the concrete to burst. 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 at 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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