TFK is doing nothing more than obfuscating the fact that a deceleration greater than 1g needs to occur for a force amplification of an insufficient static load to break up a structure below which is designed to handle several times that load. This is how shock loads apply more force than a static load.
Tony, there is no need whatsoever for this bizarrely stated condition to be true.
I am looking at a glass coffee table. If I could find myself a bowling ball, I am certain that the coffee table would support it with a FOS of about 5-10. (I could gently place that many balls on the table without it breaking.)
And yet, if I dropped the bowling ball onto the table from a height of one story, then the glass table would shatter instantly, while the bowling ball went thru a deceleration far, far less than 1g. The bowling ball's deceleration would be almost unmeasurable.
And yeah I know the difference between ductile & brittle substances. This makes no difference whatsoever to the principle.
When you say that ">1g deceleration required because the bottom structure supported the upper structure before the collapse", you are attempting to connect the pre-collapse-initiation load carrying capacity
of the intact structure to the post-collapse-initiation energy absorbing capacity
of the massively damaged structure.
And the exact factor that makes your assertion false is the fact that, as soon as the collapse begins, EVERYTHING is loaded
in completely different ways than it was in the intact, static structure.
It simply illustrates clearly that the forces applied, and the energies lost, depend on "specifically what breaks" & "how much energy is required takes to break it".
Now, I will agree to this:
IF (and it is one absurd monster of an "if") one were somehow able to surgically slice the towers into two pieces, do zero other damage (which is impossible), raise the upper piece one story, and drop it so carefully that, on contact, every single component matched perfectly with its mating component ...
AND at the very instant of contact, all of the cross connections and cuts were magically, instantly healed ...
THEN one could imagine that the forces & stresses & energies might rise through their static loading states. And, if analyzed correctly (considering dynamics), one might be able to construct some relationship between the pre-collapse loading condition & the post-collapse impact energy absorption.
Of course, this is so far removed from sanity...
But, Tony, if that's what cocks your pistol, you get right on that project. Let me know how it turns out.
Meanwhile, your attempt to construct some theorem that "a destroying structure must undergo more than 1g of deceleration in order to destroy something that could statically support it" is proven false by the simple bowling ball / glass table counter-example.
Tom
