>> The City is asking to see wind loading calculations for 90 MPH as well
>> as
> calculations for radial ice. I am trying to convince them that I will
> have
> it
> nested most of the time (which I will). The info I got from US Tower has
> a
> lot
> of detail but it only goes up to 70 mph. Has anyone run these
> calculations
> on
> this tower for 90 mph both fully extended and nested?
> For neighborhood aesthetics, I really want to stay with the tubular look.
>
> I think someone has already mentioned that it won't make that
> windspeed
> fully extended. The last one I got a PE stamp for (I think it was a
> 72-footer) was for 85 MPH and it was rated for a 25 pound load. The
> rating goes to
> zero and below at higher windspeeds.
>
> You better get the lattice one or go with a non-crank-up
> self-supporter
> or a guyed tower to get what you need.
>
Washington State has adopted the International Building Code (IBC) and it
appears that many other states are doing likewise. I looked at the
windspeed charts that accompany the new code and, if I'm reading it
correctly, the minimum design speed is 85 MPH no matter where you live and
obviously higher is some locations. Here in Lacey (near Olympia), they've
adopted 90 MPH.
Tower manufactures like US Tower seem to be behind the times. I've talked
to them several times and their 130' crankup, which isn't even in the
catalog, is the only tower they would spec at 80MPH. This towers lists for
over $40K and they still won't give adequate IBC specs. For their 106' and
89' models, the highest windspeed that they would spec is 70 MPH. I don't
mind paying for engineering, but I would like to go into it knowing that the
manufacturer already believes that the tower is adequate. Those of us who
live in IBC states need to start pressing the tower manufacturers for specs
that comply with current laws. I'd like to put up a 100'+ free-standing
tower that can handle 30 sq ft at 90 MPH, and have just about decided to
give up on the ham-oriented manufacturers and start talking to the
commercial manufacturers. At least they understand windspeeds over 70 MPH.
73,
Clay W7CE
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