[TowerTalk] wind zone maps

[JVarney]

When TIA-222-H comes out it will implement the ASCE standards.
But the ultimate design forces between TIA-222-G and -H
are roughly equivalent, so need to worry :-)

Under -G, the 90 mph standard requires the use of a "load
factor" (similar to a safety factor).  There are several load
cases to be considered, but the one that most commonly controls
is 60% SF on wind and 20% on weight. Adding these multipliers
means that towers under -G have been designed to the ASCE
numbers all along anyway.

The -H standard has no safety factors applied to wind loads.
Instead, the tower is designed to fail or barely survive the
design speed, 105 mph in your case.  The -H wind speeds are
the statistically expected "300 year" wind storms.


73 Jim K6OK


Clay Autery, KY5G wrote:

>> For my QTH there is a difference....  Rev. F basic 70mph,
>> Rev G basic 90mph.  Lots of other factors.  The link I
>> sent is to a wind chart by county that is part of the
>> TIA checklist. F and G  w/ and w/o ice...

>> http://wirelessestimator.com/content/standards

>> Don't look at the latest ASCE standards or it'll break
>> your heart... It's 105mph for me....  a 15 mph bump.

>> http://windspeed.atcouncil.org/