For some reason, all my posts are being held for moderation...
One other thing to realize is that you shouldn't really be getting into a
discussion about fall radius, because that's a misunderstanding of what
"safe design" means.
The idea is that the design is strong enough to withstand a worst case load.
The design goal is to make the probability of failure so low that you don't
worry about the consequences. This isn't a temporary structure. Think of
it this way: do they ask for a fall radius for a house or skyscraper? No..
they're designed to withstand all reasonably expected loads. Likewise
things like utility poles, etc.
For temporary things like cranes, sure, you analyze for fall radii.
Likewise for "high value" situations (rocket gantrys for manned
You might ask to see the part of the building code that asks for fall radius
(I suspect that there isn't any...)
Jim Lux, P.E.
----- Original Message -----
From: "John WA2GO" <firstname.lastname@example.org>
Sent: Thursday, January 13, 2005 4:53 AM
Subject: [TowerTalk] Tower "DROP ZONE" or "DROP RADIUS" for Rohn 25G &Trylon
> The Building Inspector is requiring my engineering drawings to specify
> he is calling the "drop zone" or "drop radius" of the tower. He wants to
> see what is the radius of the circle it will all land inside when it all
> comes crashing down. (perish the thought!)
> I couldn't find this figure in the Rohn catalog anywhere. The one engineer
> talked to didn't seem to know about it either.
> In case anybody here knows about these, here are some possibly relevant
> figures for each tower I need this figure for:
> 1) A 98' Rohn 25G, guyed for 90 mph at 95', 63' and 32' at a guy radius of
> 80', with 33' boom on top antenna.)
> 2) A 108' Rohn 25G guyed for 90 mph at 105', 70', 35' at a guy radius of
> 88', with 24' boom on top antenna.)
> In both cases, assume 7 sq. ft. of wind load at top of tower plus 4 sq.
> of wind load at 2/3 tower height and 4 sq. ft. of wind load at 1/2 tower
> 3) A 96' Trylon Titan freestanding with 4.5 sq. ft. at 97' on a 23' boom,
> 4.5 sq. ft. at 67', and 4.5 sq. ft. at 37', plus 3.1 sq. ft. at 77' and
> sq. ft. at 47'.
> If someone can tell me what the values are for the figures I need, or
> I can look to find these figures, or how to calculate them myself, I would
> be very grateful!
> 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
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