In a message dated 5/22/02 9:21:39 PM Pacific Daylight Time, ford@cmgate.com
writes:
> E.g. US Tower boasts of huge loadings at 50 MPH. I get 50 MPH many times a
> year. Twice in the last two weeks! The 50 MPH rating is a JOKE!
Actually the brochure/specs haven't been updated but the towers are all
rated for 60 MPH (which ain't much use since the lowest rating in the country
is 70 MPH).
> Other
> manufacturers, like Rohn, will rate them at 70, 80, 90, even 110 MPH.
> Making a realistic comparison is difficult unless you have the blueprints
> and know how to read them...
Blueprints aren't very useful. You need CALCULATIONS - that's what a PE
does for you.
>
> Short of hiring a PE, what's a tower owner wanna-bee to do?
Follow the LXC Prime Directive and "DO what the manufacturer says". If
it's not something obviously covered by the manufacturer, then you do need a
PE to bless it. He will also give you the appropriate base and anchor
designs.
The US Tower PE is a really good guy and can do calcs for most states and
conditions. Obviously if you want to put up a crank-up in a real windy area,
then your capacity will drop significantly; i.e. a UST MA-series tublar comes
out to about 25 pounds of capacity at 85 MPH.
If you can't con one of your ham-engineer buddies to run the calcs for
you, check the ARRL website under Volunteer Consulting Engineers (VCE) where
there are guys who can help you through this.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for commercial and amateur
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