All,
Have a couple of questions that I was hoping one of the many learned people
on this reflector could help me with, for my own understanding.
1. I have a ham buddy who is putting up a 72' freestanding tower and as
part of the permit process had to have the drawings reviewed and approved
by a New Jersey PE. One of the things the PE said was that the size of the
base had to be increased from the 4x4x7 (or whatever the exact dimensions
were per the mfg) to 5x5x8 (essentially one foot larger in each
dimension). So my question is, what does that do for the strength of the
tower? It seems to me that all it does is make it more difficult for the
entire tower (including the base - intact) to tip over, which seems like a
pretty unlikely failure anyway?
2. I have heard that the size of the base is such that it would support the
tower and rated load, at the rated wind speed, even if the base was not in
the ground (i.e. sitting on top of the ground). Is that true - always,
sometimes, never?
3. Does anyone know of a reference source that talks about the windload
ratings of a crank up tower as a function of the height it is raised
to? In other words, if my tower is rated at 50mph winds with 9 sq feet of
load, at its full height of 67', what is the rating if it is extended to
half that height? I believe the rating increases as the tower is lowered
but I have not found anything authoratitive (or semi-authoritative) that
discusses this - even at a generic level.
Thanks in advance,
Rick
W2RDS
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