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[TowerTalk] Rohn 25/Crankup loading

Subject: [TowerTalk] Rohn 25/Crankup loading
From: "Pat Barthelow" <>
Date: Sat, 29 Jan 2005 10:13:37 -0800
List-post: <>
From: "Hank Lonberg" Said:

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.

Lonberg Design Group, Ltd.

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


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