[TowerTalk] Rohn 25 leg deformation

[Michael Tope]

I noticed the other day when climbing the 60 foot Rohn 25
tower at W6UE that I had squeezed the u-bolts around the 
tower legs a bit too tight. The u-bolts are Dornan 1 1/2" 
muffler clamps with double serrated saddles which we use 
to mount 1/4" thick steel vertical shear plates along the 
tower legs. Each shear plate (~8" x 6") has a ~1/2" hole 
drilled in its bottom corner (the one furthest away from 
the tower leg). This hole is used as a tie point for the 
top guy wire thimble. The shear plate is positioned 
parallel to the tower leg such that the plane of the 
shear plate is parallel to the guy wire which attaches to 
it (e.g. the angle between plates is 120 degrees). 

Anyhow, when I replaced the top set of guys on this tower,
I must have gotten a little carried away with the u-bolts
that attach the shear plates (I was concerned that the 
downward tug of the guys would cause the plates to slip
down the tower leg). The end result, is that each of the
tower legs is no longer circular in cross section where
it passes thru the u-bolts, but rather somewhat elliptical.
The oblongation is very noticeable (probably almost 1/8"
difference between major and minor diameters). This tower
carries a pretty big wind load (~20 square feet), so I 
am a little concerned that I have compromised the structural
integrity of the top section. Anyone have any thoughts
on this? 

Thanks,

Mike, W4EF..................
 



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