At 3:52 PM +0000 4/18/03, Chris Pedder wrote:
>At 09:27 18/04/2003 -0400, Yuri K3BU wrote:
>>"Properly designed self supporting tower, with design loads, for certain
>>weather conditions and outfitted with at least one set of properly
>>placed guywires (with proper anchors) will be able to withstand
>>greater loads or more severe weather conditions than without guy
>>wires."
>>....
>
>I find myself in the strange situation of agreeing with Yuri on this
>one! ...To suggest that guying, correctly, a self-supporting tower
>will reduce its survivability is laughable.
>
>Chris G3VBL
1. I agree with Yuri and Chris (and, IIRC, Bud Hippisley, K2KIR) on
this basic technical issue.
2. I said as much in a brief post of my own before either had posted
their comments. However, this is not my main point. Please read on.
3. I disagree with our list moderator's opinion that Yuri's comments
were inappropriate.
4. I believe that, if anything was inappropriate, it was our list
moderator questioning Yuri's educational basis for his opinion, when
others who had given opinions that were less well based (or not at
all based) on mechanical science and engineering were not challenged.
However, this is not my main point, either.
5. To make progress, we must discover physical reality, not simply
what people (even _respected_ people, which includes our list
moderator) believe. It does not help us to hear an opinions without
its basis. If anyone believes, say, that adding lightly- or
"10%"-tensioned guys to a nominally self-supporting tower increases
its likelihood of failing, it's OK for him to say so but he doesn't
help us if he doesn't also say what reasoning supports his belief.
6. Instead of questioning people, or their foundations, let's
question _opinions_, and _their_ foundations. If an argument is
correct, it doesn't matter what person recites it. If an argument is
false, it doesn't matter if its proponent has a Nobel Prize in the
field. IIRC, both Yuri and Bud presented physical and mathematical
reasoning for their beliefs. IIRC, no one has exposed a flaw in
their reasoning.
7. To save anyone the trouble of asking: I am not a Professional
Engineer; I do not design towers or other structures; and I do not
pretend to be qualified to do so. My minor technical contribution to
the "guyed self-supporters" thread was that, because a guy had a much
greater "lever arm" than a self-supporting tower base, it should
help. I thought that this reasoning and its conclusion should be
obvious to someone knowing mechanics; and Yuri, Chris, and Bud have
confirmed my thinking and provided quantitative examples. I did take
several undergraduate and graduate-level courses in the mechanics and
dynamics of structures in the Dept. of Mechanical Engineering at
M.I.T.; I received "A" grades in all of them, back when an "A" meant
something; and I passed both written and oral examinations on this
topic for my Ph.D. in Instrumentation (a joint degree program of the
Depts. of Mechanical Engineering, Aeronautics and Astronautics,
Electrical Engineering, Physics, and Mathematics) at M.I.T. I also
taught mechanics (among other things) at M.I.T. for about 25 years.
This qualifies me as an academic, but not as a real-world expert. So
I am sincerely interested in hearing from some of the real-world
experts on this list. But what I need to hear is sound
scientific/engineering reasoning, with hard numbers and real-world
facts. Can someone, say, in the tower industry cite a publication
that we can read?
73 de Chuck, W1HIS
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