Re: Anchoring
Guys, I don't know what your background is, but... your comments about pipe
are bizarre.
Structural shapes are commonly found as Fy=36 and Fy=50 ksi carbon steel.
Tubing: I can buy nearly anything, in many material strengths and grades.
To much higher strengths.
Piping: Same thing. Maybe even more versatility, if you know where to look.
To much higher strengths. Of course, if you're comparing to Home Depot
water pipe, you'll always see tubing as "better".
Whether seamless or with a 100% joint efficiency, it's easy to get good,
strong pipe also. What's more important is... what shape/material/length
you can find, and for what cost.
What's really important, besides it not corroding away?
In tension... tensile strength and net cross-sectional area.
In bending... section modulus, i.e. size and shape (possibly in 2 axes) and
tensile strength.
An angle, in bending, is an inefficient shape - meaning, more weight (and
cost) for the same moment-resistance. "I-beams" are pretty efficient for
that. Squares, rectangles and circles aren't bad.
If it were bending in just 1 axis, I'd normally prefer a structural shape.
Easy to find; easy to work with.
If you're not sure what you're doing, get ahold of someone with some
experience - not just anecdotes - or go check out what works well at major
stations which have stood the test of time.
And note that when you bury an I-beam and connect your guy at its top, 6'
up or whatever, all of a sudden you don't have just a tensile load - you
have a bending moment in your beam and an overturning moment in your
foundation. So if you don't want to calc it, don't put it any higher than
absolutely necessary... and double or triple the size of beam that you
think might be satisfactory. Your problem, if it occurs, typically won't be
at the turnbuckle connection, but at the base of the beam...
regards,
Dave N3AC
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On Wed, Nov 16, 2022 at 7:46 PM KD7JYK DM09 <kd7jyk@earthlink.net> wrote:
> On 11/16/2022 15:12, Ken WA8JXM wrote:
> > John is correct that "pipe" is poor for structural use. The proper term
> > for what you need is "tube" which is structural and available in a wide
> > range of diameter and wall thickness. It is also available in round,
> > square or rectangular form.
>
> Adding to the confusion...
>
> Pipe is a thing, tube is another, and "structural" is something else,
> specific, that looks like a pipe, or a tube. I've bought 20 pieces of
> "structural" this year (not called tube, or pipe in the industry, just
> structural, then describe what you really want, but the "structural"
> specification), and it is quit different from pipe, or tube, and those
> would get me a similar looking, but entirely different product of
> drastically different specs and price.
>
> Be certain of what you need, and ask for, and if possible, compare
> everything before committing.
>
> I use what what the utilities use, a thimble eye. I use 6'x3/4" with a
> 12x12" plate on the bottom sunk four feet down, the hole back-filled
> with rock, gravel, and slurry, tamping as I fill. I think they are
> rated for 32,000# pull each. Here is an example:
>
> https://www.comstarsupply.com/5-8x10-thimbleyebolt-j8051.html
>
> They come in different diameters, and lengths, I think 10' is the longest.
>
> It gets to the point, and does a job. They come in single, double,
> triple eyes, et cetera. One can buy them online, and many electrical
> parts houses carry them.
>
> That being said...
>
> I have a project coming up, where something else would be more
> practical. In that case, the guy mount will be a 12" concrete piling,
> sunk about 36" down, and a metal T secured to the top, the web pointing
> upward, with 6 j-bolts, then two holes through the web, one for each guy
> (per direction) on a roughly 16' mast.
>
> Kurt
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