The only correct answer is "Only your PE knows for sure".
I think you should be able to work with that square pipe, but it would help
if you knew what the material was exactly.
What you'll need in the ground totally depends on your soil conditions.
Steve, I'm using 1/2" angle steel members for elevated guys on 110' of Rohn
45 loaded with 3 XA's and a 402CD.
This is much less expensive than I beams, since you dont have to do any
torch cutting or web reinforcement.
I paid about $350 for 3 NEW 10' pieces with holes for rebar and a hole and
camfer for the equalizer plates in one corner, and primed. The long edge
(about 4" if I remember correctly) faces towards the tower.
They are 4' in and 6' out of the concrete with just some holes and
crossed-over rebar through the bottom to hold it in the approximately 1/2
yard of concrete.
My design was approved by my PE and they've been up for several years with
no signs of problems
73, Ty K3MM
To: don@kcnet.com, towertalk@contesting.com
cc: (bcc: Tyler G Stewart/BENN/CEC)
Subject: Re: [TowerTalk] Elevated Guys - 2nd Try
In a message dated 98-09-27 19:23:41 EDT, you write:
> I have been given 4" square .25" wall pipe in 3 20' sections. The PE
that I
> have been working with is on vacation (somewhere in the Europe I think)
and
> won't be back for 2 more weeks.
This is an engineering question and I don't know if you included
enough
information for an engineering type to respond. That's the only response I
would put any creedence in. All other anecdotal comments are not valid.
>I plan on only 4' above ground. I also got
> 3" .25" thick angle iron, 20' long. Reinforcment?
> What do you all think? Worth using? Fill with cement? My new light
poles?
You need I-beam, not angle iron. Three inch is too small anyway.
The 4-inch square stuff is too small too. If you welded a couple of
them together, that would probably be okay (PE blessing aside). A 4-foot
height is relatively low but that means that you've got 4X the forces on
the
anchor due to the 4-foot lever and bending moment.
Cass County is a 75 MPH windspeed zone so it's not bad - 70 MPH is
the
lowest rating they give.
>
> Previous articles have indicated that 5" - 8" round pipe.
If you use BIG pipe, it'll be okay. It's when people try to use 2-3
inch
Schedule 40 or 80 pipe that they'll get into trouble. As I recall, filling
the
pipe with concrete adds approximately 30% to the strength.
If in doubt, over-engineer the heck out of it or wait until your PE
gets
home. You'll never regret doing it right but you might lie awake nights
when
those big storms roll through wondering if the tower will survive or crash
if
you don't.
Cheers, Steve K7LXC
http://www.championradio.com
Champion Radio Products
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