[TowerTalk] 4 Way Guying

[n4kg@juno.com]

The Worst Case Load with 4 way guying is IN LINE
with any one of the guy wires.

The Worst Case Load with 3 way guying is at 30 degrees
to any one of the guys (90 degrees to the opposite guy).

For identical towers with equal anchor spacing the advantage
to 4 way guying is about 14%.  This is due to the 30 degree
offset between the worst case windforce and the opposing
tension in the guy wire which must be multiplied by the
cosine of 30 degrees  ( 0.86).

I expect the MAIN reason for the increase in allowable loads 
for the tilt-over towers is that they are designed for only
48, 58, or 68 ft. whereas the guyed towers are rated for
their full allowable heights (200 ft for R25, 300 ft for R45).

The newer catalogs take height into account but do NOT
give the ratings for guys attached at the TOP of the towers.

There are an infinite number of guying possibilities and Rohn
only provides a few limited examples.  If you deviate from their
designs, you are on your own to perform the analysis and
determine the safe limits, or to hire a PE to do it for you.

de  Tom  N4KG



On Fri, 31 Mar 2000 14:39:02 -0500 RCM <robrk@pgh.net> writes:
> 
> Without digging out the books, Rohn uses 4-way guys on their 25/45
> foldover. Maybe they are
> taking some compromises to make the foldover work, but at last 
> reading
> the the load ratings
> were up quite a bit. My tower engineering brain ain't to big, but it
> look like you get a lot more
> wind load ratings with four guys, with or without the foldover.
> 
> --
> 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
> 

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com