[TowerTalk] [Bulk] Re: Buried section base...and lightning protection.

[Grant Saviers]

For a guyed tower not much of a base is needed, only enough square feet 
to be below the soil bearing limit at max wind load and then enough to 
not slide from the force created when the tower bends. When I think 
about  a pier base which induces no bending moment in base section, the 
only lateral force is the sine(angle of tilt) x total vertical load.  
Angle of tilt is a very small number of degrees so there isn't much 
horizontal force.  For a buried base, there are overturning forces in 
the base which are beyond my pay grade to calculate.

I think the Rohn larger & deeper base footings are designed to insure 
the freestanding tower is stable with the construction loads before the 
first guys are attached.  Or work is stopped due to the approaching 
thunderstorm.  At 35' on R25 before the first guys are attached is an 
informative experience.

My PE engineered base for 140' of Rohn 65 is 4x4x2' and the soil 
pressure is less than me standing on one foot.  We installed temporary 
guys after 30' of tower was up as first guys were at 60'.

Grant KZ1W

On 1/5/2016 11:49 AM, AA6DX - Mark wrote:
> 'Sez guyed ...Mark AA6DX
> -----Original Message-----
> From: john at kk9a.com
> Sent: Tuesday, January 05, 2016 11:07 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Buried section base...and lightning protection.
>
> 1/6 of a yard of concrete for a freestanding tower?
>
> John KK9A
>
>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Buried section base...and lightning protection.
> From: Ken <wa8jxm at gmail.com>
> Date: Tue, 5 Jan 2016 12:42:18 -0500
>
> I am totally amazed at  how concrete has weakened over the years.
>
> For a 50' guyed tower, all I used was 30" square and 8" deep.
>
>
> Ken WA8JXM
>
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