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Re: [TowerTalk] Square vs Round Holes

To: Dino Darling <>
Subject: Re: [TowerTalk] Square vs Round Holes
From: Jim Lux <>
Date: Mon, 12 May 2008 14:50:54 -0700
List-post: <">>
Dino Darling wrote:
> -=Since everyone else takes liberties of changing the SUBJECT name of
> the thread, let me give it a shot also.=-
> "Save on concrete"?  Its not the shape of the hole that matters, but the
> size of the foundation. :-)
> A 36" hole would need to be deeper, and in my opinion, too small of a
> diameter.  Even a 60" hole would need to be deeper to make up for the
> loss of the "corners" of a square hole.

Not necessarily.  If the mass is being used as a "big weight in the 
ground", then that's what's important.  If it's for a free standing 
tower, then it's mostly resisting the overturning moment, so long and 
skinny is probably better than short and wide, for a given amount of 
concrete, just because the lever arm is longer. (one deep piling 
provides the same resistance as several horizontal pilings of the same 
size, because it's direction independent).

If the base is basically to "float" the downforce from the guys and 
resist the shear force from wind on the tower, then big and flat might 
work better... I don't know off hand.

The points made about trying to get the local inspector to sign off on 
the canned drawings from the mfr are well taken, though.  OTOH, if you 
need wet-stamped drawings, you're already paying the engineer, so have 
him/her figure out the dimensions of the round vertical piling.  It's 
not my field of expertise, but for someone who does foundation 
calculations, it should be the work of less than an hour.  A local 
engineer would also likely be aware of the relative construction costs 
too. (equipment rental, operators, concrete costs)

A lot of the drawings for towers used by hams were originally done in a 
different era, when hand excavation was more common.  A big square pit 
is easier to hand dig than a skinny well, leaving aside the fact that 
neither is particularly safe to do, but the square shallow pit is safer 
than the well.  If you're standing in the hole, anything smaller than 4 
feet across is hard to maneuver the shovel in. (yes, miners do it in 
smaller tunnels and shafts all the time, but they're optimists from the 
get go..)


> ** Lee George wrote: **
>  Hi Scott,
>  Nobody said the hole has to be square. Find a utility pole contractor
> that 
>  has a digger derrick truck with a 36" bit.
>  ALL OF the traffic light / street light poles in your city have round
> holes and you cant knock 
>  them down with a truck. Trust me, I seen it tried.
>  Might even save on concrete.
>  For the life of me cannot see why ham folks love square holes, much
> easer to dig round
>  ones. 

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