On 10/31/2011 1:09 PM, K8RI on TT wrote:
> On 10/31/2011 11:02 AM, Bill Gillenwater wrote:
>> So, what is the best anchor for sandy soil, like in central Florida?
> A *BIG* block of concrete! The NW anchor for my tower is near the edge
> a dried up swampy area. The soil is sand, loam which is very coarse and
> has little holding power. I have a 17,000# block of concrete in there
> and the elevated guy anchor has shifted some where around 8 or 10 inches
> over 10 years.
> It all depends on how much it has to hole in how much wind.
> For tube, round or square, in sand, get some 1/4" steel plate and weld
> to the sides, or even build a cage, but that's difficult to describe.
> I'd have each side extend out a minimum of a foot. I'd prefer more
> but then you have to back brace it. Which is OK, it just takes more
> material, more welding, and more care. Brace on back, front is pretty
> much flat. one 2" wide channel of 1/8" steel, set back about 6" at the
> pipe depending on the width of the ears with a support direct from where
> the braces join to the pipe. It's easy to see when drawn, but harder to
> put in plain English.
I should have said one 2" brace for each vertical foot of plate.
We recently used this approach to a heavily loaded 60' tower where the
anchor was in sand.
> Roger (K8RI)
>> 73 Bill K3SV
>> ----- Original Message -----
>> From: "Jim Lux"<email@example.com>
>> Sent: Sunday, October 30, 2011 2:51 PM
>> Subject: Re: [TowerTalk] PIPE ANCHORS
>>> On 10/30/11 10:39 AM, Grant Saviers wrote:
>>>> A couple more comments, some not covered before: (all comments w/o
>>>> engineering calcs - YMMV)
>>>> 1. Square tube is stiffer/stronger than round pipe or wide flange beams
>>>> (I-beams) of same #/ft..
>>> Hmm. I'm not sure this is true. Bending strength goes as the radius to
>>> the 4th power, and for a given perimeter, a circle has the section
>>> moment. (sort of like a circle has the most included area for a given
>>> Cross sections with right angles are easier to use in construction,
>>> especially for bolted connections, and a I beam typically has more metal
>>> farther from the center than a square tube (which is why they use that
>>> However, in "practical sizes commonly sold" it might be true that
>>> squares are stronger than circles.
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