Is there a picture of the collapsed tower ?
> On Dec 10, 2013, at 9:43 AM, john@kk9a.com wrote:
>
> The whole tower rotated, harmonic oscillation may have been the
> destructive factor. It would definitely be nice to use star guys on a
> structure like this.
>
> I wonder how well the 160m yagi worked compared to a large vertical array.
>
> John KK9A
>
>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] [MWA] OH8X 80-160 monster tower collapses
> From: Jim Lux <jimlux@earthlink.net>
> Date: Tue, 10 Dec 2013 05:45:50 -0800
>
> On 12/10/13 5:34 AM, Djordan (personal) wrote:
> I wonder what the original design spec was for the system 75mph or 100mph...
> Wonder what the cost differential would have been to raise the spec 25 mph.
>
>
>
> On a large system like this, often times the limiting aspect/failure mode
> is not a simple strength to resist aerodynamic drag effect, but some
> interaction, or a dynamic effect.
>
> The Tacoma Narrows bridge did not fail because it wasn't strong enough. It
> failed because it wasn't *stiff* enough and the design had significant
> wind induced torsional loads. One might say that the "Q" was too high,
> although the aerodynamic design was also such that the wind excited the
> oscillation in the first place.
>
> Until some sort of failure analysis is done, we don't know if perhaps
> there was a failed component, etc. That is the design accommodated the
> expected loads, with a factor of safety to account for manufacturing
> variability, but it was that non-zero probability of failure that bit
> them.
>
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