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Re: Addendum to wind load calculations




----- Original Message -----
From: "Murray Peterson VK2KGM" <vk2kgm@ihug.com.au>
To: "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Monday, May 14, 2001 10:08 PM
Subject: [amsat-bb] Addendum to wind load calculations


> Hi Everyone,
>                         if you have been reading my email about
windloading
> on structures, I thought I better add that wind is a dynamic load, note
just
> a static load and so wind induced vibration should also be avoided.
>
>     The most hazardous mechanical resonant frequency to avoid is 0.3 Hz
> (dynamic wind loads have most of there energy at this frequency - ie a
gust
> every 3 seconds) but if in doubt, is is better to have all mechanical
> resonant frequencies above 10 Hz as there is usually almost no significant
> component of wind loading above that frequency.
>

I wonder how many people here have seen then now infamous film
of the wind induced vibration, with frequency about 1/3 hz, on the
Tacoma Narrows Bridge.  If not,  everyone should see it once to
see the power of this dynamic loading.

Bob N4HY

> Regards,
> Murray Peterson
> VK2KGM
> (Yes - I am a Structural Engineer)
>
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