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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