[TowerTalk] Fwd: [Bulk] Military mast and guy-wire tension?

[Hans Hammarquist]

Wouldn't the idea of moving the anchor points as far away from the tower as possible (space allowing). I want to remember calculating that an anchor point 135% from the attachment height gives the least sway on a tower. That would also give less downwards force than the commonly recommended 80%.


Please correct me if I'm wrong with the 135%.


Hans - N2JFS



-----Original Message-----
From: Grant Saviers <grants2 at pacbell.net>
To: dw <bw_dw at fastmail.fm>; TowerTalk <towertalk at contesting.com>
Sent: Sat, Feb 6, 2016 1:14 pm
Subject: Re: [TowerTalk] [Bulk]  Military mast and guy-wire tension?

comments in line

On 2/6/2016 7:41 AM, dw wrote:

>
> And there is some concern about tower failure due to downward
> compression from over-tightening?
Yes.  Two of the simple failure modes are exceeding the compression 
strength of the tower leg and column buckling of a thin slender column.  
The initial tension is added to the tension created from wind forces so 
does reduce the maximum load permitted from wind. Towers have to lean a 
bit for the tension in the guy to increase, which offsets the wind 
load.  The tension in the guy generates a horizontal force to oppose the 
wind load and a vertical force which increases the tower compression 
loads.  Simple geometry can be used to calculate those forces.  Keeping 
towers and masts straight ("in column") is what multiple guys levels do, 
otherwise they would buckle with just a top guy.