[TowerTalk] Tower Questions

[alsopb]

Guys,

This whole discussion reminds me of a statement made by an individual
who will remain unnamed.  It was at a Federal Licensing Inquiry. 
There was a particular technical issue that had to be resolved.

The fellow, who wanted the license granted, asked of the regulators
"What answer do you want and in what form".

He had the accurate perception that licensing issues boil down to one
thing-- to satisfy the regulators.  It often doesn't have a much to do
with the technical adequacy or technical points.

I think this is what is going on here.  The local officials, who
probably don't really know much engineering, are used to seeing values
x, y and z in particular boxes of THEIR form.  If you can't supply
them that way, it's a no go.  

Too bad that Engineering doesn't really matter.  Now for the flip
side, your $ are invested.  You want the engineering correct.  Like
the zoning official who didn't want to see and rebar in the tower base
hole. OK I took it out when he approved it.  Then it went back in
(according to mfgr's spec) when the concrete was poured.  

My cynical view.

73 de Brian/K3KO

Kurt Andress wrote:
> 
> Joel wrote:
> >
> > Perhaps  we  can give you answers to some of your questions after working with the TRI EX engineering staff.  Well, here goes;
> >
> 
> SNIP discussion.
> 
> > Hope the above answers some of the questions asked on towertalk about a week ago  If there are any comments, I will pass it along to the P. E.  that put the above together. ..
> 
> Joel,
> Thanks for taking the time to collect this information, and to the P.E..
> 
> Wind speed gradients due to elevation shouldn't be too hard to recognize
> or accept. Apparently, my comments have been misunderstood by some to
> say that the wind speed doesn't change with elevation. That was not
> said. The comments were directed at how the cited spec's treat the
> problem by using a "constant" basic wind speed and applying varying
> factors to generate varying dynamic pressures to account for the changes
> of elevation.
> 
> In the response text I see components of the Uniform Building Code (UBC)
> and components of EIA-222 E, & F. As pointed out subsequently by
> tower2sell,the EIA spec does not use the A, B, C, exposures cited in the
> response.
> Actually, UBC '97 uses B, C, & D exposures (table 16-G, page 2-28). The
> tabular information comes from EIA-222. The "height factor", Kz (called
> "exposure coefficient" by EIA-222-F, how's that for nomenclature
> confusion?)values in the table agree with what I get at 20' 40' 60' 80'
> &
> 100'(EIA-222-F para 2.3.3, page 4), but the Gust Response Factor (Gh)
> doesn't. Gh varies according to the formula in para. 2.3.4.1, which says
> that it is 1.25 from ground level up to 33', then it decreases to the
> 1.16 value shown at 100' (continues to decrease above there).
> 
> I haven't spent enough time to make sense out of all the dynamic
> pressures in the table, other than find that the 20.01 value given for
> 100' is what EIA-222-F produces for 70 mph basic before the drag
> coefficients are applied.
> 
> Just wanted to make sure everyone understands that this was a mixed spec
> response, and that no one tried to take this and go off and do
> something with it. A copy of the appropriate spec is worth a thousand
> posts.
> 
> The response pointed out that crank-up tower section overlaps are
> problematic as expected. One of the riginal generic questions (where is
> it
> gonna fail) was not answered, and I wouldn't have expected it to be.
> Again, that can vary with each design. The answer can be found by
> careful examination of the tower calc's.
> 
> --
> 73, Kurt, K7NV
> 
> --
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