[Top] [All Lists]

[TowerTalk] guy rod angle

To: <>
Subject: [TowerTalk] guy rod angle
From: (Stan or Patricia Griffiths)
Date: Thu, 06 Sep 2001 01:21:57 -0700
I took another look at my Rohn Catalog and I now see where they do list the rod
angle.  Funny, I never noticed that before . . .  Still, they don't tell you how
they caluculated it . . .

I learn something new every day . . . even after 48 years of ham radio.


Michael Rauh wrote:

> Jerry, Stan, Dave, Tom,
> I agree with Jerry and Stan - the angle is probably not critical.  Rohn
> presents the angle to 0.1 degree in their guyed tower drawings.  This seems
> impossibly precise to me - there is probably way more sag or bow in the guy
> anchor than that.
> I also suspect that Dave is correct when he suggests taking the vector sum
> of the loads on the guys when the tower is at its rated wind load to find
> the guy rod angle.
> In thinking about this problem I realized I don't know how to calculate the
> individual loads on each guy wire.  I use a rigid body model for the tower
> that will give the total load on the guys, but won't tell me how the guys
> share the load, at least as far as I can see.  To figure out the load on
> each individual guy, I think I will need to consider how the tower deflects
> under load.
> Consider a tower with two sets of guys and an antenna on top.  I could start
> by assuming the tower is fixed at the top and the base.  I calculate the
> wind load and how the tower will deflect under that load.  Draw a curve,
> deflection vs. load.  Then assume the lower guy is attached at mid-point,
> draw a curve of elongation vs. load.  The load on the second guy is where
> the curves meet.  The reminder of the load on the tower, including the
> antenna load, is absorbed by the top guy.
> But wait!  The top guy elongates under load too, relieving the load on the
> bottom guy.  So I will have to set up a system of simultaneous equations in
> order to get the loads on each guy.  I will need equations for the
> elongation of the top guy, the bottom guy, the deflection (bowing) and the
> pivoting of the tower.  If the tower has a pivot base that is all I need,
> but if the base is cast in concrete I might need an equation to account for
> the force needed to tilt the tower as the guys elongate.
> Does that sound right?  Do you know of any references where this kind of
> problem has been worked out?  I know Kurt Andress has found guy loads using
> a finite element program.  I need to understand the principles involved
> before I resort to a program!
> I think it would be very cool to know how to find the loads on the
> individual guy wires in a tower system.
> Best Regards,
> Mike Rauh, NV7X
> Reply to
> _________________________________________________________________
> Get your FREE download of MSN Explorer at

List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!!

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>