[Top] [All Lists]

Re: [TowerTalk] New tower info request

To: <>
Subject: Re: [TowerTalk] New tower info request
From: "K8RI on TowerTalk" <>
Date: Mon, 1 Jan 2007 04:31:34 -0500
List-post: <>
Although just a nit and too large a guy wire would put undue stress/pull on 
the legs, the highest stress point is probably going to be the base. 
although the lower guys are more of a straight out pull.  I'd taken some of 
the old American Steel (two bolt) towers down that had 1/4 steel guys 
properly tensioned.  The bottom three sections took a jack to get them 
apart. The sections had actually "belled" out between the bolts or at least 
above the bottom of the open section.  This effectively swaged the sections 
together.  Over the years I took down three 90 foot tall American Steel 
towers like that with 1/4" steel guys.  All three required the use of a jack 
to get them apart.  As the cross section of the tower leg was no longer 
straight this should have substantially reduced the strength in the vertical 
plane. As memory serves all three legs in each case were pretty much equal, 
but that means with one person with enough equipment to hit 200# total was 
probably seriously overloading the tower.

Every thing was done well, except the strength of the tower had not been 
taken into consideration or the consequences of using over size guy wire.
Guyed at three points that were close to equally spaced and the top set 
within  a foot of the top, each section weighs 30# for a total of 270# a bit 
of trig will show those guys were putting substantial downward force on 
those towers. Use the cosine of the angle to horizontal at the tower.If the 
top guys are at 45 then cos(45)* 670# tension = 352# downward force for each 
line or 1055# downward force *just* for the top set of guys.  Add to that 
the tension and weight of the guys for all three levels plus the weight of 
the tower and it has to be close to 2000#.

How many of us would intentionally put up a 90 foot tall TV tower and then 
put a one ton weight on top of it?  How many of us would then add another 
200# consisting of ourselves and equipment to the tower by climbing it?

That was a long time ago and I'm not taking any more American Steel towers 

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2 (Use return address from home page)

> Is there a correct pull ?
> ````~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Easy answer to your question.
> Go by whatever Rohn recommends for the guy wire.  If you use 3/16  inch 
> EHS,
> you should have approximately 390 lbs of force on it.  If you use  1/4 
> inch
> EHS, use approximately 670 lbs.  If you use 5/16 use around 1100  lbs. 
> Just use
> whatever the book recommends for guy wire and you should be  fine.
> It is possible to use too heavy a guy wire and the 10% figure would 
> actually
> be trying to pull the tower apart.  An extreme example would be  using 
> 5/16
> on Rohn 25 and using 1100 pounds of pull on it...not too smart!
> Bill K4XS/KH7XS
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list


TowerTalk mailing list

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