Don-
You can find many tower manufacturers' foundation diagrams and rebar
schedules on-line. You might search for a tower with similar height and
wind load specs to what you plan and use their canned foundation design.
For comparison, my 89' crankup uses >10 yards of concrete and #7 (7/8"
diameter) rebar. Concrete, rebar and digging labor is relatively cheap.
Better to have the wind collapse your steel than lift out the foundation!
73,
Steve
N6SJ
----- Original Message -----
From: "John Lemay" <john@carltonhouse.eclipse.co.uk>
To: "'Don Bowen'" <don.bowen@earthlink.net>
Cc: <TOWERTALK@contesting.com>
Sent: Saturday, May 05, 2012 1:40 AM
Subject: Re: [TowerTalk] Rebar schedule
> Don
>
>
>
> I see you've already had some replies and suggestions.
>
>
>
> I'm not a PE, but I am a chartered engineer here in the UK. However, my
> expertise is not in foundation design ! I'll go on experience and
> intuition.
>
>
>
> A "yard" of concrete is not likely to be enough. This is particularly
> important (point has already been made), if the mast could fall on people
> or
> property. I would suggest that two cubic yards is likely to be the right
> sort of volume (that will weigh something over four tones). Your four
> fixing
> points should not be close to the edge, so with 42" centers, I would
> suggest
> the base would be 60" across. Then work out the depth to give yourself the
> recommended volume. If you can, make the sides vertical and the base
> horizontal, and don't use formwork - simply pour the concrete into the
> hole
> against the earth. Don't worry if there's a bit of water in the bottom,
> concrete sets under water.
>
>
>
> As for the rebar, which was your original question, sorry I can't help. In
> the UK, many foundations such as this are simply mass concrete, and that's
> how my own mast is.
>
>
>
> Good luck.
>
>
>
> John G4ZTR
>
>
>
>
>
> _____
>
> From: Don Bowen [mailto:don.bowen@earthlink.net]
> Sent: 04 May 2012 12:33
> To: John Lemay
> Cc: TOWERTALK@contesting.com
> Subject: Re: [TowerTalk] Rebar schedule
>
>
>
> On 5/4/2012 3:07 AM, John Lemay wrote:
>
> Hi Don
>
>
>
> Not enough information !
>
>
>
> How tall is the mast ?
>
>
> To the top of the fourth section is thirty six feet.
>
>
>
>
> Will it be guyed or freestanding ?
>
>
> Free standing
>
>
>
>
> What will you put on top ?
>
>
> hy-gain TH-3JRS triband and a Yeasu G-450A rotator.
>
>
>
>
> What soil do you have 3ft down ?
>
>
> Gravel, rocks, clay.
>
>
>
>
>
>
> Regards
>
>
>
> John G4ZTR
>
>
>
>
>
>
>
> --
> Don Bowen KI6DIU
> http://www.braingarage.com/Dons/Travels/journal/Journal.html
>
>
>
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>
>
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