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.
73
Roger (K8RI)
> 73 Bill K3SV
>
> ----- Original Message -----
> From: "Jim Lux"<jimlux@earthlink.net>
> To:<towertalk@contesting.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
>> perimeter).
>>
>> 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
>> shape).
>>
>> However, in "practical sizes commonly sold" it might be true that
>> squares are stronger than circles.
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