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Ahhhhh, just have to say a couple words here....
I saw that video when in college taking material science class. It was =
totally
awsome.. as the bridge resonated with a certain velocity of wind. Sort =
of how
you can blow on the edge of piece of paper.. and make it vibrate and =
make a
nasty sound. Well this is sort of what happen to the bridge, the wind =
make it
resonate to DEATH! In this class we had a lab... and one of our =
experiments
was to find the resonance of our building we where in. A motor type =
soleniod
was mounted to the concrete floor and made to vibrate, while =
measurements
where taken on walls and such. It only took around 200W to make the =
building
"feel" like something was happening. Very spooky! The solution to that =
bridge was to change the shape as I recall.. making it curved instead of =
straight.
The material was not changed but the configuration sure was. Again.. =
neat
video and I saw it actually fracture...literally throwing the center of =
the bridge
up and down.. tearing it apart. Whow...
Now my question then is similarities... a "STATIC" field (the wind at =
constant
speed) can be a magnet... ("STATIC" magnetic field).. and a conductive =
wire
would be the bridge. Is there any change.. that we can make this wire =
'vibrate'
from the static magnetic field? You would think "wind across a bridge =
surely
could not make a bridge vibrate". Hummm thinking hard on this =
one...there
must be a specail case somewhere....
v/r Ken Carrigan
>Don't remember the date, but the place was the Tacoma Narrows bridge =
locates
>in Washington State. From what I have heard about the bridge, it =
collapsed
>under its own vibrations when the wind would blow through the canyon it =
was
>crossing over. Engineers, after rebuilding it several times, deduced =
what
>was going on and changed some of the materials in the bridge, changing =
the
>mass and altering the resonance of the bridge. That is how I understood =
it
>anyway.
>BillP
>-----Original Message-----
>From: Ted Gallop <gallope@planet.curtin.edu.au>
>To: keelynet@DallasTexas.net <keelynet@DallasTexas.net>
>Date: Thursday, January 28, 1999 9:16 PM
>Subject: A Request, or Two...
>
>
>>Hello Members,
>>
>>I'm new to this group, and hope to be able to contribute =
constructively as
>>time goes by...
>>My particular interest, at the moment, is sound/accoustics/harmonics, =
etc.
>>
>>Can anyone help me with the following two requests.
>>
>>I've read all of the keelyNet files on Ed Leedskalnin. However I was =
under
>>the impression he had written quite a bit about his "sweet 16". Are =
there
>>any copies of this writing extant? If so, where can I get my hands =
(eyes?)
>>on it.
>>
>>Also, I have seen over the last few decades an occasional film clip of =
a
>>suspension bridge (somewhere in the USA I think) swinging and swaying =
and
>>twisting, and eventually disintegrating in high winds - the usual
>>explanation being that its 'natural frequency of vibration was in tune =
with
>>that caused by the wind' or something like that. Does anyone know the =
date
>>and place, and how I could get some of the footage (avi format?)
>>
>>Many thanks.
>>
>>Ted Gallop
>>
>> -------------------------------------------------------------
>> To leave this list, email <listserver@dallastexas.net>
>> with the body text: leave Keelynet
>> list archives and on line subscription forms are at
>> http://dallastexas.net/keelynet/
>> -------------------------------------------------------------
>>
>
>
> -------------------------------------------------------------
> To leave this list, email <listserver@dallastexas.net>
> with the body text: leave Keelynet
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