[TowerTalk] what is 'circular tie' as is used in a towers concrete base?

[Patrick Greenlee]

Harbor Freight (Northern Tool too, I think) sells hydraulic pipe benders 
that come with interchangeable "jaws?  mandrels?" of different sizes.   
These aren't all that expensive and do a great job.  They have a built 
in rollers and a hydraulic jack that you manually pump to get the 
bending.  Easy to pump.  Goes slow enough that there is no worry about 
going too far too fast,  Easy to get the desired radius of curvature.  
You can single handed bend a circle with a 20 ft length of rebar or make 
a much tighter bend if desired.  I have had mine for over 20 years.

Patrick        NJ5G


On 10/20/2015 11:05 PM, Roger (K8RI) on TT wrote:
> My opinion:
> Typically the rebar only adds strength to the concrete base.  IOW, You 
> don't need as large a base, or as strong a mix when rebar is used.  If 
> you were "positive" the base could maintain structural integrity under 
> any conditions you wouldn't need rebar.
>
> Regardless of whether welded or tied, The rebar normally doesn't need 
> a rigid connections.  The ties only keep the rebar in place during the 
> pour.
>
> If you don't need precision and are not making sharp bends in big 
> stuff you might be able to do the bending with a manual conduit 
> bender.   Welding just makes building a rugged cage that can stand 
> rough handling easier.  Just be sure to use rebar made for welding.  
> Welds on the normal stuff are quite fragile.
>
> Bending rod, rerod, pipe, etc...into a circle is usually done with 
> three rollers.  The rollers  (Which usually have a radius cut into 
> them to keep the rod centered) are mounted in a triangular shape with 
> the bottom of the center one slightly below the tops of the outside 
> rollers  (The height of this roller is adjustable).  To bend much of 
> anything, these things can be pretty hefty.  The distance between the 
> rollers is surprisingly short.  Having them close reduces, or 
> eliminates waste.
>
> There is a bit of a learning curve, but it's neither steep nor long. A 
> rough explanation:  The center roller is raised so the rod can be 
> inserted  over the outside rollers and under the center roller. Then 
> the center roller is lowered and tension applied. The first pass 
> produces a shallow arc. The center roller is lowered for each 
> successive pass which tightens the arc eventually into a circle
>
> I've seen the rollers mounted into the top of a steel bench with a 
> movable center wheel.  The rollers are powered and a center screw, or 
> hydraulic ram powers the movement of the center roller.  With those 
> you have to be aware of the thd of tht piece coming back, or you could 
> skewer yourself.
>
> 73
>
> Roger (K8RI
>
>
>
>
> On 10/20/2015 11:29 AM, StellarCAT wrote:
>> Rohn says to use 8 #7 rebar (SERIOUSLY! 7/8”!!) ... and then it shows 
>> ‘#4 circular ties 2 1/2” OC with 2” cover with 24” laps’
>>
>> huh?
>>
>> I’ve always just dug a hole – usually around 3 x 3 x 3 ... put the 
>> tower section in (with temp guys) ... put in a few pieces of 1/2” re 
>> bar and been done with it .... but now I have to follow the Rohn 
>> specifications which seem onerous at best (I know, I know – guys that 
>> say “follow it to the letter”) ... and I’ve no clue what #4 circular 
>> tie is. SURELY its not #4 rebar BENT in a circle!?
>>
>> Googling so far hasn’t shown me anything that helps.
>>
>> Gary
>> K9RX
>>
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