[TowerTalk] Additional Guy Needed?

[Stan Griffiths]

>At 05:26 AM 8/31/98 -0400, you wrote:
>...
>>Think about the guy situation for a moment.  In an early Rohn catalog that I
>>have which is dated September 1969, Rohn specifies the Gross allowable load
>>on the bottom section of 45G to be 19,440 pounds!  I know they don't publish
>>this number or any other number telling you the Gross allowable load on the
>>bottom section in the current catalogs.  I also don't think the materials or
>>design of 45G tower sections have changed either.  So if you tensioned all 6
>>of your guys to 10 percent of their breaking strength, added the weight of
>>the tower, beams, rotator, guys, coax, etc, how much is it?  About 4000
>>pounds, maybe.  I would not worry for an instant that I was putting too much
>>weight on the bottom section, even by adding two more sets of guys.
>
>But what if the wind blows sufficiently to put, say, 3500 pounds tension on
>each of the windward guys?  Suddenly, there's a lot more than just the
>static load.   I also wonder some about the stability of the bolted
>inter-section attachments.   Looks like we need that PE!
>
>
>73,  Pete Smith N4ZR
>In wild, wonderful, fairly rare WEST Virginia

Hi Pete,

Yes, we DO need that PE.

If the wind DID blow enough to put 3500 pounds on the windward guys, how
strong of a wind would that be?  200 MPH?  I don't know, but I'll bet you
would see some other failure before the bottom section buckled, such as all
the elements blown off the antennas or a guy anchor uprooted.

Also, with that tension on the windward guys, there is probably no tension
in the other ones since the tower would deflect toward them slightly putting
a little slack in them.

This is the stuff a good PE can answer without guessing . . .

Stan  w7ni@teleport.com


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