[TowerTalk] How many tower sections i can install??

[TexasRF at aol.com]

Hi Douglas, you can achieve a a greater guy point distance by using four  
guys instead of three. You would not want the guy to guy angle to exceed 120  
degrees in any case.
 
Your roof dimensions would allow guy to guy angles of 120, 60, 120 and 60  
degrees. With the tower mounted in the center of the roof and assuming the  
anchors are at the edge of the roof, a guy to guy angle of 120 degrees,  the 
distance would be 20.0 ft to the anchor. The distance between anchors  
would be 34.6 ft, 20 ft, 34.6 ft and 20 ft.
 
So, in this case, you could guy the tower a couple of ft below the top and  
three 10ft sections would have a anchor/height ratio of 66.66%.
 
We typically use an 80% ratio mainly because that is the number Rohn  
specifies for all of their tower models. It is a good compromise between load  
capacity and space required.
 
Considering that these towers are used up to 180ft in height or more, it is 
 reasonable to move anchor points inward for reduced heights. The issue in 
doing  this is that Rohn has no published data for doing this. The wind load 
rating has  to be reduced and it takes engineering skills to properly do 
the calculations.  It is not rocket science however.
 
I would be concerned about possible roof damage as much as the tower  surviv
al. It is conceivable that using the roof edge as a turning point for the  
guy and then a ground anchor would be stronger. Something else that would  
benefit from an engineers blessing.
 
73,
Gerald K5GW
 
 
 
 
 
In a message dated 8/25/2015 9:14:22 P.M. Central Daylight Time,  
co8dm at frcuba.co.cu writes:

Hi,

I would like read your ideas. 

I have few 10 ft  section of a tower (it is like a Rohn 25G).

I would like install few  section over some part of my roof...The roof is 
concrete...as you know many  house in the Caribbean has concrete roof ...it 
is 24ft by 40ft...so, i have  calculating and the distance from the base to 
the guy anchors is 14 ft  !!!

I know the distance from the base to anchor points is 70 % of the  tower 
height...so, 70% of 20 ft is 14ft, that´s mean 2 tower sections...right  
??...Is it possible install 3 sections adding more guy´s set  ???

Thanks,

73....Douglas,  CO8DM
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