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

[Chris Wynn]

This thread reminds me of my first tower when I was in college.  A close friend had taken down an older Rohn 25 tower.  He gave it to me and told me to repaint, which I did.  Back in college, I barely had enough money for books, much less concrete.  Anyway, after saving up for what seemed like forever, I finally dug the hole, threw the tower in, tied the tower to some rebar with old coat hangers, and poured.
After a week of curing, I invited everyone over to help me put it up.  Unfortunately, after we all got ready to stack, we discovered that I had cemented the wrong side of the tower into the concrete--upside down!  I almost threw in the towel at that point and gave up on ham radio!
Using my redneck ingenuity and my short stay at GA Tech, I machined metal pins to reverse the section.  I subsequently erected the tower with no problems whatsoever.  This past summer while erecting tower number two at my present QTH, I ran across those metal pins that I used.  Such a small bump in the road at that time, but back then, it seemed like a game changer!
Good luck!
Chris WynnN4XFASEDXCARRL LIFE MEMBER Christopher L. Wynn
Attorney-at-Law
Christopher L. Wynn, ESQ., P.C.
8473 Earl D. Lee, Suite 300
Douglasville, Ga., 30134
(770)942-8661 (Landline)
(770)577-1626 (Telecopier)
chris at chriswynnlaw.com 

    On Tuesday, January 5, 2016 3:57 PM, Grant Saviers <grants2 at pacbell.net> wrote:
 

 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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