[Towertalk] Climbing Masts

[K7LXC@aol.com]

In a message dated 11/27/02 9:31:41 AM Pacific Standard Time, faunt@panix.com 
writes:

> Frankly, I'd worry more about the mast to tower attachment.  Climbing
>  a 20 foot mast could put a LOT of sideways stress on the top few feet
>  of the tower, where the mast is supported.  

    Actually it's more of a vertical load, not sideways. 

>  But that's also where the
>  stress is in high winds when you're not up there.

    While that's true, most guyed installations have the guy attachments in 
the direct vicinity of the top of the tower so the mast forces come out at 
the guys and also the rotator so the forces are spread out somewhat rather 
than being concentrated at one point. 

    Towers are primarily designed for headloads of numerous configurations. 
>  
>  Are there failures at that point, even in high winds?

    Mast failures are bent masts right at the top of the tower due to the 
bending moment of the mast and antenna load. Tower top failures are 
relatively rare - the mast will typically bend before the tower does. 

Cheers,
Steve    K7LXC
TOWER TECH