[TowerTalk] rebar (was 900 MHz tower)

[John Blalock]

Jim,

Universal Towers in their instructions for their free-standing aluminum 
towers states that rebar is  not needed for their concrete bases.  Should I 
put in rebar anyway?

73,

-john, W7AAY

----- Original Message ----- 
From: "Jim Lux" <jimlux at earthlink.net>
To: <K7LXC at aol.com>; <towertalk at contesting.com>
Sent: Friday, December 30, 2005 11:32 AM
Subject: [TowerTalk] rebar (was 900 MHz tower)


> At 06:43 AM 12/30/2005, K7LXC at aol.com wrote:
>
>> >  However as far as welding goes, rebar CAN be welded, but it  takes a
>>special
>>technique, and requires some knowledge of the bar material  and the right
>>welding rod.  This isn't a "get the old buzz box out and  tack everything
>>together" kind of operation.  And, as always with  structural kinds of
>>things, you need to talk to your local regulators.
>>
>>         It's been my experience  that rebar in tower bases isn't usually
>>'structural'. It's primary purpose is to  hold the concrete together while 
>>it
>>cures to prevent cracks in it.
>
>
> Concrete has no real tension strength, so the rebar provides the needed
> tension strength.  If your tower is a guyed tower with only compression
> loads on the big block o'concrete, you're right, the rebar might not be
> doing much.  However, if you have a free standing tower which transmits
> bending loads to the concrete as tension (on the upwind side) and
> compression (on the downwind side), you'd better have the rebar in there.
> Even on a guyed tower, there are shear loads on the concrete, which, by
> definition, are a combination of tension and compression loads.
>
> Upshot.. rebar is most definitely structural.
>
>
>>Rebar  schedules are in the drawings for each tower
>>so be sure to follow them.
>>
>>     BTW rebar comes in # sizes; i.e. #4, #6, etc. This  refers to 1/8 
>> inch
>>increments. For example, #4 is 4/8ths or 1/2 inch; #6 is  6/8ths or 3/4 
>>inch.
>>
>>Cheers,
>>Steve   K7LXC
>>TOWER TECH
>
>
> Jim
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>