[TowerTalk] Rohn 25/Crankup loading

[Pat Barthelow]

>From: "Hank Lonberg" kr7x at comcast.net Said:
>Malcolm:
>
>If you notice the sections get larger as you go downward from the top. The
>tower sections get stronger and can handle more moment as you go downward.
>Just like the moment diagram for a cantilever beam, which they are albeit
>vertical. The maximum moment is at the bottom and reduces as you go towards
>the top. Rohn 25,45,55,65 are constant in section size.
>
>Regards
>Lonberg Design Group, Ltd.

Folks:
I notice something different also, in how/where the load is carried on each 
section of a crankup.  Assuming no blocks installed, and the lift cable 
carrying the total load of the elevated tower sections,   the load is not 
carried down the corners of the tower, at least not directly.   It is 
applied at single  point sources in each tower section, namely the cable 
pulley axle bolts, in my tower, located on the side of the tower trellis 
work. The corner joints of the tower 'float'.  That is, there is no direct 
downward transfer of stress though the three corner tubes of the tower.   
Does this single point source of loading change any basic dynamics of load 
transfer down the tower structure?

73, DX, de Pat Barthelow  AA6EG
(831) 646-0388    aa6eg at hotmail.com