[TowerTalk] TOWER GUYING and Apology

[Kurt Andress]

T A RUSSELL wrote:

>         Most of us are now in agreement that  maximum  GUY
>         tension occurs when the wind is PERPENDICULAR to
>         one of the guys in a 3-way system, which is at 30 degrees
>         to the primary load bearing GUY.     de  N4KG
>
>         The TOWER  load appears to be minimized when the wind
>         is IN  LINE  with a guy as stated.    de  N4KG

Agreed! And I'll add that the tower bending loads should be included with
the vertical compression I think Tom is referring to.     de NI6W

> >When the wind blows exactly between two sets of guys, the guy loads
> >are at their lowest value, and the tower bending loads are at their
> >highest value. This is caused by geometry completely!
>
>         I still disagree with the first part of this statement.  When
>         the wind bisects two guys spaced 120 degrees, the GUY
>         tension should be EXACTLY   EQUAL  to the tension in
>         a single guy when the wind is IN  LINE  with that guy.
>         This results from the simple relationships in a 30-60-90
>         degree triangle where the forces along the short leg are
>         1/2 the forces along the hypotenuse.   These TWO cases
>         represent the lowest GUY tension conditions.   de  N4KG
>
>         Assuming EQUAL tension in two guys when the wind
>         bisects those legs, AND that this tension is equal to
>         the tension in a single guy when the wind is in line
>         with that guy, the TOWER  load from the bisecting
>         case  will be TWICE that of the IN  LINE case since
>         there are now TWO guys with equal tension pulling
>         down on the tower.   This results in the maximum
>         additional load on the  TOWER. (Pretension loads
>         not included in this analysis, only the additional load
>         due to  wind).          de   N4KG

I now understand the source of our disagreement. I'll take credit for the
misunderstanding! The problem is that I didn't comsume enough bandwidth to
describe the details of the load case and analysis.
I agree with the above statements. My calculator says the same thing Tom's
does.
The above conclusion comes from looking down on the tower and solving for
the load components. It is a 2 dimensional look at part of what is going
on.


>  Apology to Kurt, NI6W and the group.
>
> SNIP

> This is a perfect example of what can happen when one does
> not proof read, mull over, and edit one's response.   I usually
> do in fact  re-read and edit most of my posts before sending.
> In this case, I hurriedly posted a reply while getting ready for
> work and sent it off.  I will endeavor to be more careful!
>
> de  Tom  N4KG

Thanks Tom, I have the same problem.
Good thing for me, it's the weekend, so I'll spend enough time to clarify
the conditions that led to my comments, which were obviously far to
consise. Then put up a post that will clarify what is was doing, what I
found, and why I think it happens.

73, Kurt

--
YagiStress - The Ultimate Software for Yagi Mechanical Design
Visit http://www.freeyellow.com/members3/yagistress



--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm