On 8/12/13 11:28 PM, Roger (K8RI) wrote:
On 8/12/2013 5:06 PM, Richard Karlquist wrote:
The topic of adding guys to self supporting towers has been
discussed a number of times on this reflector, but I am
still not clear on exactly why it supposedly won't work.
You forgot to add the guy tension.
This is a bit more simple than the analysis that gave leg compression, but
if i use the right trig function...it's a rough view of the forces.
Self supporting towers are much more complicated as they have leg
compression that a pier pin mounted, guyed tower does not and must be
stronger for a particular wind load
complicating all this is that for some towers, the limiting member is
the diagonal cross braces. They tend to be longer and skinnier, and so
have lower buckle loads for column loading. So while the vertical
members might take the load without failing, the diagonals may not.
The distribution of uniform vertical load between corner tube/angle and
diagonal is tricky: typically it's not something simple like a free
pivot attachment, so you have to deal with bending and torsional loads
and the relative stiffnesses of the members at that scale as well.
You need to get the engineering analysis for the tower in question and
start looking at it in detail.
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