Question for Apollo20

[einsteen]

No buckling here. Nosiree.

http://www.internationalskeptics.com/forums/imagehosting/879045fd54c927534.jpg

Thanks for this Gravy, did you see the time stamps ?

 

[einsteen]

@Golden Bear
The crush-down crush-up model is an approach. David Benson gave a good example and that can be
summarized in the following image

http://i10.tinypic.com/878bupk.gif

There is of course always a crush-up during the crush-down but it can be neglected compared with the crush-down,
the (non-coupled) differential equations are already complex enough. The layer of floors does the job
and that layer will grow, the top block will follow this layer of floors. And as explained by DaBigGuy the difference in velocity
(or better acceleration) leads to a different force, I agree with him. This however does not mean the collapse
features are completely explained.

@Major Tom
interesting photo archive

 

[gumboot]

Gravy obviously those images are faked

I'm sure I remember someone trying to explain away that buckling as an optical illusion caused by light refracting as it passed through hotter air caused by the fires.

-Gumboot

 

[Dave Rogers]

And if Major Tom wants another collapse mechanism he should try reading Cherepanov's papers dealing with fracture waves.....

I wouldn't recommend it. Cherepanov starts with the assumption that the towers fell in freefall times, and it all goes downhill from there. He concludes that the entire structure of the towers was destroyed instantaneously at the commencement of the collapse, so the intact structure we've all seen below the collapse front is obviously just a mass delusion. His work is just as scientifically flawed as the work of the truth movement, he's just blaming a worldwide conspiracy of structural engineers for designing unsafe buildings rather than the US Government.

Dave

 

[Crazy Chainsaw]

Crazy Chainsaw, what do you think of the weld in the picture below?

[qimg]http://www.sharpprintinginc.com/911_math/superficial_weld.jpg[/qimg]

It is a broken weld fractured along a slip plane caused by micro fractures expanding in the said slip plane do to distortions from layering in the weld left behind in the welding process.
http://www.springerlink.com/content/n078976316p36015/
I have seen hundreds of such weld fractures that is how a weld is supposed to break if compressed and then subjected to side forces.


Modern Ultrasound weld treatment is designed to eliminate that problem.

All steel contains dislocations, eliminating them with ultra sound bombardment strengthens the welds.

PS. the side that the tape measure is placed across, broke first, the lower part formed a hinge joint, as evident in the fractures.

 

[Max Photon]

Request for column weld photos

Major Tom,

Could you kindly post a few more photos of WTC column welds.

Thanks.

 

[Max Photon]

Bending moments would cause column splice to fail before columns seriously deformed

I'm referring to the perimeter and core columns. Even if not subjected to lateral forces large enough to shear the column splices, the mechanism of buckling would introduce large bending moments at the column splices which would cause them to break long before the column underwent any serious deformation.

[bold mine]


I agree.

 

[Major_Tom]

NB writes:

I'm referring to the perimeter and core columns. Even if not subjected to lateral forces large enough to shear the column splices, the mechanism of buckling would introduce large bending moments at the column splices which would cause them to break long before the column underwent any serious deformation.

The problem with applying the same logic to the perimeter is that the bolt collections were cleaverly staggered.

Note in the "etching" in the Bazant-Zhao paper:

Diagram c shows a conception of perimeter column "buckling" along a "crease". We know that these creases do not actually exist.

You cannot simulate "creases" with a bolt and spandrel plate failure mechanism.

Notice how bolt connestions are staggered for strength

Einstein wrote:

There is of course always a crush-up during the crush-down but it can be neglected compared with the crush-down,
the (non-coupled) differential equations are already complex enough.

We are beginning to understand that weld failure (or, as I would say, "assisted" weld failure) is the clear cause of the division of the 1400ft+ core columns into much smaller sections.

If you apply that to the Bazant model, you will quickly realize that there is nothing inherently stronger in the top 15 stories of a core column than in the bottom 85 stories.

As the core columns "collide head on" (a requirement in the Bazant energy equations) the notion that , for each individual column, the welds within the top 15 stories are much stronger than the welds within the bottom 80 floors will be seen as ridiculous.


Some of you seem confused about the "special powers" of an object in an accelerating reference frame.

At the moment of impact, the destructive effects will be independent of whether one of the objects was accelerating or not.

The argument that the columns in the upper part were "magically stiffer" that in the much stronger lower part simply because it was in an accalerating frame of reference is empty.

Max, I'll see what I can do.

 

[SDC]

The argument that the columns in the upper part were "magically stiffer" that in the much stronger lower part simply because it was in an accalerating frame of reference is empty.

Crikey! Then you are the guy who keeps sending those spams!!