I have a spreadsheet with which I can do a full EIA/TIA-222F wind
load analysis of a Rohn SSV self-supporting tower. To "calibrate"
my results, I loaded several towers as Rohn claims (one antenna at
the top and another 30 ft down), and tried to get the over-turning
moment (OTM) and shear force (SF) numbers of the June 96 Rohn catalog.
For a 100-ft SSV in 90 mph wind, if I reduce the antenna drag
coefficients
by exactly 20.00%, my OTM and SF agree with Rohn's within 0.06% or
better.
However, for 80-, 60-, and 40-ft SSVs, my results and Rohn's catalog
diverge.
I'd appreciate any info about
1. the wind loads (pounds force at X mph wind - no gust or height
factors) on SSV tower sections,
2. the pounds force loads at various wind speeds that Rohn uses
for the antenna structures in their calculations, and
3. any clarifications about whether Rohn based their calculations
on 222C or 222E (or both), and
4. the name of an engineer at Rohn willing to talk about their
tower stress calculations.
I read TowerTalk daily, but would prefer a direct reply to
k5ra@pulse.net.
Thanks.
73, Tim/K5RA
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