[TowerTalk] Fw: Re:[AR902Mhz] Tower Installation

[Jim Lux]

At 12:12 PM 12/30/2005, K7LXC at aol.com wrote:
>
>In a message dated 12/30/2005 9:23:55 A.M. Pacific Standard Time,
>farmer.aj at gmail.com writes:
>
> >>         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. Rebar  schedules are in the drawings for
>each  tower
>
> >  The rebar is not just to "hold it together while it  cures", it
>provides tension strength to the concrete.  Concrete has  high
>compression strength, but has very little tension strength.  The  rebar
>provides the tension strength.
>
>
>         Okay, I stand corrected.  Does that make it "structural"? Wouldn't
>the ground provide the  constraint/tension? I can see where a concrete block
>sitting on top of the  ground would need the tension but below grade isn't 
>that a
>moot point?

No.. you'd be relying on the compressive strength of the soil, which is a 
lot less than concrete.  It would be much like burying an unwelded tower 
segment in dirt.  You could, of course, just stick 20% or so the height of 
the tower in the dirt without any concrete. This is like putting up a 
telephone pole.