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 ```Pat: Actually the vertical load is indeed passed thru the cables and is transferred to the next lower section by the pulley connection to its top thru the stiffening band around the section. This distributes the load to all 3 legs. Bending moment does not necessarily create axial load in the legs. It creates axial stress in the leg sections and this is additive with the axial stress caused by the vertical load in the legs to create the total stress in the legs. The leg sections act like little columns between the bracing points. When the stress value gets large enough the leg can fail thru lateral buckling between the bracing points. The overlap sections act like a ferrule in a fishing rod they transfer the lateral load between them by the upper section trying to move the lower section in one direction at the top of the overlap and the upper section trying to move the lower section in the opposite direction at the bottom of the overlap section. This creates equal and opposite forces which transfer the lateral load to the lower section. It also creates a moment due to the distance between the top and bottom of the overlap which transfers the moment from the upper to the lower section and so on. I have written a program that calculates this load, force and stress transfer between the sections of crank-up towers in order to analyze them for loading conditions for my clients. It is tedious but not that complicated. Hope this helps your understanding. Regards Lonberg Design Group, Ltd. Hank Lonberg, P.E.,S.E. / KR7X President -----Original Message----- From: Pat Barthelow [mailto:aa6eg@hotmail.com] Sent: Saturday, January 29, 2005 10:14 AM To: kr7x@comcast.net; mringel@bluecrab.org; towertalk@contesting.com Subject: Rohn 25/Crankup loading >From: "Hank Lonberg" kr7x@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@hotmail.com _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```