"Concertina" collapse

[Heiwa]

Dr G, aka Apollo20, co-author of the BLGB paper about a 'One-way crush down' theory of WTC 1 on 9/11 adopted by NIST as true has some new thoughts how to start a one-way crush down. Listen to the music:

I am still formulating my ideas on this but I am wondering if the verinage technique used to bring down the Balzac Building could actually also be a possible mechanism for the early collapse motion of WTC 1 - especially for the core. I would suggest calling this a "concertina" collapse because the columns behave like the bellows of a concertina; but I would add that this type of failure must involve "column connector" shearing failures. In plastic buckling the load vs. deflection curve is concave, while the load-deflection curve for shearing is convex. I beleive the convex shaped curve fits the drop vs. time data for WTC 1 quite well.

BTW - verinage technique is French for controlled demolition.

Any thoughts about above are welcome.

Does he mean con-certina?

Anyway, that the upper part of WTC 1 above the fire zone behaved as a concertina being pressed together before anything else, incl. one-way crush down, happened below is quite correct. Are we hearing some new music from Bazant & Co?

[jaydeehess]

Actually verinage refers to the "vertical or horizontal displacement of a load, deck, etc. with jacks.
Dictionary of Civil Engineering By Jean-Paul Kurtz
http://books.google.ca/books?id=tWvOUz1QiAAC&pg=PA734&lpg=PA734&dq=french+to+english+dictionary+verinage&source=bl&ots=Pe0CnMr1YJ&sig=T-Z7_FM3OMnQ9CrdbZoc9cYvXD0&hl=en&ei=goPWSZnMLKPEMozAhIQP&sa=X&oi=book_result&ct=result&resnum=1#PPA734,M1

The word concertina is correct as well. Its a cousin to the acordian. Apollo20 is using an analogy.
http://en.wikipedia.org/wiki/Concertina

[Furcifer]

Anyway, that the upper part of WTC 1 above the fire zone behaved as a concertina being pressed together before anything else, incl. one-way crush down, happened below is quite correct.

No it didn't.

A bellows has a very uniform shape and is specifically designed to flex repeatedly. Buildings aren't (to that extent) I'm not sure why Apollo is making the analogy....

A second read and I see he notes "early collapse motion" and "especially for the core". You've probably overlooked these key words as well. He's talking about the collapse zone, not "the upper part of WTC 1 above the fire zone".

Your English fails you again Heiwa.

[ozeco41]

Dr G, aka Apollo20, co-author ....has some new thoughts ...:

I am still formulating my ideas on this but I am wondering if the verinage technique used to bring down the Balzac Building could actually also be a possible mechanism for the early collapse motion of WTC 1 - especially for the core. I would suggest calling this a "concertina" collapse because the columns behave like the bellows of a concertina; but I would add that this type of failure must involve "column connector" shearing failures. In plastic buckling the load vs. deflection curve is concave, while the load-deflection curve for shearing is convex. I beleive the convex shaped curve fits the drop vs. time data for WTC 1 quite well.

....Any thoughts about above are welcome.

just the common mix of complicate sounding words; internally inconsistent statements and general fog about "WTF is he trying to say".

Whenever people try to explain by "crush up"; "crush down"; "crush any other directions" OR, ususally in a different context, "crushing" it is near certain they are either confused themselves or trying to confuse others.

The terms "crush up" and "crush down" arose from certain early overly complicated engineering attempts to explain the tower collapses.

Whatever the utility of the terms they are near useless as most often used in conjunction with explanations that treat the top block and lower tower stub as if they acted as homogeneous entities - peudo "solids" as it were. That was not how the "collapse that actually happened" took place so it is an hypothetical OTHER situation.

However, back to basics, the two key realities are that somehow the top block started to fall and once started a global collapse occurred.

Common to both those realities is that the interactions between top block and "stub" involved multiple instances of single element contacts admittedly very close in time and many undeniably overlapping in their timeframes of interaction.

Simply put once the top block was moving downwards and wedged inside the outer tube that falling mass would strike a single floor. 10 or 20 floors of TOTAL STRUCTURE initially still an integral whole, later demolished itself into componentry, but still the same falling weight, would obviously ovewhelm any single floor. Possibly a 20--50 times overload at an engineering guess. But there is no need to calculate details - it would be and was "overwhelming". any lay person can see that and so we don't need engineering pseudo science to confuse the non technical readers.

Now reverting to the obtuse, convoluted and confused statement from "Dr G" as quoted above.

He starts off by stating he is talking about the initial movement of the Top Block. "...the early collapse motion of WTC 1..." Both the tower initial movements were at least in part precipitated by column bowing and overloading as "axial load carrying struts" once they bent out of line.

whatever utility there may be in the term "concertina" there is simply no way that any individual column would collapse as a multi fold concertina. A bold asserion of engineereing reality that I will not even bother to support. Simple basics.

So, if "concertina" means anything could Dr G be referring to the whole structure in macro?

There is no evidence of that.

So does he have some "mid level" idea of where it fits in???

No point commenting further until he makes his concept clearer.

And there is no need for it to explain the "collapse that actually happened" - even if he resorts to applying it to the core. Doing so would add the further unknown that we cannot see what happened to the core. But it aint too hard to work out what would have happened behind those obscuring dust clouds.

So, simply put, forget Dr GF's explanation till he makes it clearer.

And when/if he does it sure looks like he is down a path to nowhere.