From the page:


"The World Trade Center Towers as Bio-inspired Structures:
Characteristics of their Design and Demise

This work was presented at the 2006 Society for Experimental Mechanics =

Annual Conference
Adam=92s Mark Hotel St. Louis, Missouri USA June 7, 2006
by Dr. Judy Wood, professor of Mechanical Engineering "

http://janedoe0911.tripod.com/BilliardBalls.html

Mark

Gerhard Fiedler wrote:
> James Newtons Massmind wrote:
>
>   =

>> Others have said that the weight of the top floor would accelerate the
>> lower floors and account for the rapid fall. That is an interesting
>> point, which may very well be correct. I don't know. I would love to
>> hear from someone who does. =

>>     =

>
> If it falls from the top, the weight of the top ceiling crashes on the
> floor below. There it "shares" its energy and momentum, and both continue
> to fall, however slower as if there were no floor below. And so on. To fa=
ll
> nearly like free fall, I'm pretty sure the whole steel frame has to crash
> at nearly the same time (between all floors). =

>
>   =

>> However, from all the videos, it is very clear that it started falling
>> from the bottom, not the top. If fires heated the steel, why wouldn't
>> the top have fallen first?
>>     =

>
> Maybe because the load is much higher at the bottom, and a much lower
> temperature is needed to soften it to a point where it gives in? But even
> then, in order to fall in a time that's close to free fall, the whole ste=
el
> frame has to give in at nearly the same time. Which may be possible.
>
> Gerhard
>
>   =

-- =

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