Steve: a number of times I've seen references ON A COUNTY basis to
>>wind force design criteria. do you know where I can obtain this info,
>>hopefully on line? my old, old, old Rohn book only has a map of the
>>US. I'm curious as to the design criteria for Cheshire country in the
>>stick of NH.
>>
>Hi, Charlie --
>
> It's listed in the EIA/TIA-222-E and F, the newest revision effective
>June 1, 1996. I have copies and am happy to look them up for interested
>folks. My plan is to get my Tower Tech web page up and running and
>eventually have the info on-line as I don't think it exists anywhere else.
> The pubs run $80.00 each so not everyone is inclined to have them in their
>library.
>
> Cheshire County is a 75 MPH zone but is within 100 miles of hurricane
>coastline and the values have been adjusted in accordance with ASCE 7-88 to
>obtain 50-year recurrence intervals. In other words, check with you local
>building department to see if you are subject to higher winds at your site.
> BTW, 70 is the lowest value that the charts contain so your zone isn't too
>bad except for the proximity to hurricane coastline.
>
>73 and good luck, Steve K7LXC
>
> TOWER TECH -- professional tower supplies and services for amateurs
>
Since 70 mph is the minimum listed wind velocity for ANYWHERE in the US, how
come crankup towers are always rated for 50 mph? I think I know why. You
can't put any load on them at 70 mph, at least with any kind of safety
factor. I think we, as a group, should demand 70 mph ratings from crankup
manufacturers. I know this will negatively impact their business . . . as
it should!!
Stan w7ni@teleport.com
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