Hello all,
Couple of comments on K4JA's tower failure.
The lower half of the tower was shielded from some of the wind by way of
tall trees at the edge of the field, where the woods started. The upper
half went way above the trees and took the full force of the wind.
Also, his stuff was fully rotating from the base up to the top, with
slip rings at the guy points. Because of this, the guys really had
nothing to do with limiting the twisting of the tower. It just twisted
as it wanted all the way from the ground to the top.
73 de Steve, NR4M
On 6/15/2019 7:56 PM, john@kk9a.com wrote:
I would not put more on a tower than Rohn's wind load ratings allow
just because a torque guy is used. A 6 way star guy does a great job
of minimizing twisting. There is more leg compression since there are
more guys wires however a Rohn 45 is designed to go 300' high and the
tower in the post is only 110'. I believe that twisting can cause
tower failure, K4JA's tower twisted back and forth in hurricane winds
until it failed. Adding a star guy is probably a good thing if the
antenna has a long boom. I use star guys and a taper pier pin base on
all of my towers.
John KK9A
k7lxc wrote:
I had one of these on the top guy set of my 110' R45 tower. And
I had torque arms on the lower two guy sets.
My question is aside from twisting, does this change any of the
wind loading numbers?
My suspicion is the double guy sets per face can only help but I
have never seen it quantified.
Since the capacity of a tower is determined by the leg strength, I'd
say that the use of a star guy bracket doesn't really do anything to
change it. I'm not an engineer so I don't have any calcs to provide.
Cheers,Steve K7LXCTOWER TECH
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