RFC: Bazant and Zhou Simple Analysis refuted

[Heiwa]

Cut by me to the last bit. H, don't weasel. You are obliged to say "what" you think it was. If you don't, even the wee tots at whom you claim your research is aimed will be entitled to holler "weasel" at you.

I have to disappoint you. I only claim NIST/Bazant are wrong in their analysises. Wrong cause! Buckling, potential energy, impacts!?!? Cannot produce the effect. That is easy to show using scientific methods. Too little energy. Gurich will show it in his rewritten paper.

So something else produced the effect. Using much more energy. But OT.

 

[DGM]

No, the same applies to all columns. #501 is just an example. I write for children. To keep it simple.

You write for children because they're the only ones that you can fool.

 

[SDC]

Another Stundie nomination, from one of the true greats.

Dave

I disagree. I don't think he can be ranked with the greats, yet. With Malcolm Kirkman, for example? Nah. He (Heiwa) has real potential, but he hasn't realized it yet.

Of course, he's got time. He doesn't appear to be someone who will either give up, or go out of control and commit suicide by mod.

I think he will rank more like... hmm, you're in the UK, I believe... Well, let me explain. US Baseball has its Hall of fame which elects retired players every year. And there are always controversies around this question: who is more worthy: the short-career spectacular? (Say, Don Mattingly). Or the long-career unspectacular who built up an impressive record by longevity and being consistently pretty good. (Say, Don Sutton, or Jack Morse.)

As things stand now, I predict that Heiwa will be of the latter variety; a Don Sutton among his kind. Always there, working hard, but never truly great.

Your views may differ. In this, I make no claims to certainty. Just my opinion.

 

[Norseman]

No, the same applies to all columns. #501 is just an example. I write for children. To keep it simple.

In other words, you claim that any column alone could have carried the upper block without failing, if all the other columns on a floor were removed. It is you who claimed that:

Core column #501 cannot buckle under any circumstances. It is too strong. Same applies for a majority of other core columns.

 

[e^n]

No, the same applies to all columns. #501 is just an example. I write for children. To keep it simple.

It may be true that every core column in the WTC was too slender to undergo euler buckling (Thanks Newtons Bit for helping my understanding) but they are certainly vunerable to inelastic buckling.

How much force must be applied to fail this column assuming the load distribution is not entirely uniform?

 

[Furcifer]

[snip]
So something else produced the effect. Using much more energy. [snip]

Yikes.

 

[StoneRook]

Not really! Nist states: "The release of potential energy due to downward movement of the building mass above the buckled columns (the cause) exceeded the strain energy that could be absorbed by the structure. Global collapse ensued (the effect) ."

No buckled columns below the building mass above have been identified or seen to 'buckle' at any time.

Downward movement of mass above cannot be correlated to 'buckled' columns below, e.g. the roof moves when all visible columns between floors 93-98 are not buckled.

Core column #501 cannot buckle under any circumstances. It is too strong. Same applies for a majority of other core columns.

The potential energy of mass above is not calculated by NIST.

The cause is not proven!

The strain energy of the structure is not calculated by NIST!

It is not shown that the potential energy exceeded the strain energy.

Regardless - it is not even shown that the potential energy of mass above was applied to the structure and that its strain energy is relevant.

Thus the effect (that we see) cannot be related to the proposed cause by NIST.

Conclusion - the effect, lack of strain energy and global collapse, could very well have been caused by something else. Don't ask me what.

Heiwa,

I've asked before, can you show your calculations for this?

Can you show how 501 cannot collapse under any circumstance?



You say NIST cannot prove it - can you prove what you say?

Again, please show your work here.

 

[Norseman]

Evidently a column damaged before the collapse (by the nose of a plane) is of no interest. Nor is a 180° bent core column above the initiation zone of interest - the structure above is assumed to be intact all the time during the collapse until it probably is 'buckled' in contact with ground. Same with the crumpled up perimeter column - that should be a square box - that was part of the mass above.

In a proper forensic analysis you sort out all the parts, mainly columns, in the rubble and line them up on some football fields for further study. Not too difficult. By looking at the fracture surfaces of the columns, you can establish how they were ripped apart. Also the shape of each column after 'buckling' can be established. You do not even have to move the goal posts.

You moved the goal posts big time, because you asked:

One problem is that none of the 280+ columns of the WTC1 initiation zone has been identified and analysed - damaged by plane or later 'buckled' (undefined) by heat in combination with very low compressive stresses (the mass above) and finally disappearing (how!) to allow the mass above to drop.

If you allege, as NIST, that the cause of the whole collapse is 'buckled' columns in the initiation zone, the least you need is one sample of such structural part.

And when I called your bluff, you then tried to explain it away by moving the goal posts.

And let me correct you on the perimeter column part, it was a part of the block blow. The crumbled up perimeter column looks very much like it was overloaded by the upper block during the collapse initiation. In fact the panel this column was a part of, A 209:97-100, covered floor 97 - 100. The collapse initiated on floor 98. The panel obviously broke in two parts, when the progressive collapse that initiated on the south side progressed to the position of this panel close to the north east corner of WTC 1 on the east side.

 

[Heiwa]

It may be true that every core column in the WTC was too slender to undergo euler buckling (Thanks Newtons Bit for helping my understanding) but they are certainly vunerable to inelastic buckling.

How much force must be applied to fail this column assuming the load distribution is not entirely uniform?

Buckling is always inelastic be it bending, twisting or crumpling up beyond yield stress. When it bucklebends the bending stresses are >yield, when it buckletwists the torsion stresses are >yield and when it bucklecrumples up it is the compressive stresses that are >yield. When a stress is >yield plastic deformation will start of different types and ruptures will occur if the stress >ultimate stress of the material. Otherwise it just deforms permanently. To stress a column you need a force. To deform it you need energy.

NIST fails to explain what type of buckling the 280+ columns in the initiation zone failed from. Due to low slenderness ratio of the core columns it should have been bucklecrumpling up ... but no such failed/deformed columns have been found.

Too little energy available for it, actually. Draw your own conclusions from that!

 

[uk_dave]

I thought it was the perimeter columns which failed......

...oh nevermind, it's not worth the effort

 

[Heiwa]

Heiwa,

I've asked before, can you show your calculations for this?

Can you show how 501 cannot collapse under any circumstance?



You say NIST cannot prove it - can you prove what you say?

Again, please show your work here.

You have to visit my website for it. As I am not allowed to link to it you can google with Anders Björkman + NIST. OK, the paper is written for children but maybe you will manage? 501 is a very solid column with slenderness ratio 10. To bucklebend it by compression is not possible as it will yield before it starts to bend. So only bucklecrumpleup is possible and for that you need a concentrated force of >2250 tons + a good support, which are not available anywhere. Anyway, NIST has given up the buckling idea and suggests now in its FAQ December 2007 that 6-11 floors in and above the initiation zone suddenly dropped down and caused the collapse. This is why you cannot see any perimeter columns bucklingcollapsing at all (Please note that a little bending is not equal to beckling). Evidently there is no evidence that any floors dropped down either. It is just an invention by NIST experts to support the myth that WTC1 collapsed by itself without any evil expeditious external energy input.

 

[uk_dave]

...... WTC1 collapsed by itself without any evil expeditious external energy input.

Ha!! My vote definitely goes to NIST.

Too funny.

 

[Apollo20]

Heiwa:

I am a little confused..... we all agree that WTC 1 & 2 collapsed, right, .... well that means that "floors dropped down", right, ... But you claim that "there is no evidence that any floors dropped down". So what are you saying?

And as for buckling, .... let's say there was very little buckling, and the main mode of core column failure was fracture at the weld planes. That was possible "without any evil expeditious external energy input" wouldn't you say?

 

[einsteen]

I've an other question Apollo20,

page 10 from http://www.nistreview.org/WTC-REPORT-GREENING.pdf

Prof Wierzbicki said that it takes 1.139*10^6 J to cut an exterior column,
then multiplying times 236+47*6.7 gives the often mentioned E1 value 0.63 GJ, Bazant independently derived 0.5 GJ from first principles.

In the paper we can read: Thus Wierzbicki considers floor support failure under lateral impact loading while Bažant’s considers the failure of the floor supports under axial impact loading. The fact that the energy calculated in each of these cases is about the same suggests that the energy dissipated in a floor collapse is relatively insensitive to the mode of failure of the support structures. This is a common observation in studies of collisions of large objects involving complex structures such as aircraft, automobiles, trains, and ships.

What I still don't understand is that the toppling of the block is crucial for a collapse that continues, I'm not really into columns and axial loads etc but does the above conclusion not really contradict that the toppling is relevant ?

And I don't know what Heiwa means with that single column, but it was no block standing on a single column but a large amount of columns, assume 80% is still intact then the 0.5GJ could be multiplied by 0.8, a huge amount of energy is needed.

The destroy is not directly possible form potential energy, first kinetic energy should be garthered. But in a slow movement there is not much kinetic or rotational energy. In 1d you can proof that it is absorbed, 3d is absolutely incredibly difficult but I still think it is amazing that your energy calculation (based on radial impact) is the same as a real crushing of the story and therefore the approach 3d -> 1d could be valid.

ps. and I don't know exactly where the fireproofing was dislodges, which core columns but that should give another factor. But the static load is still really a fraction of the maximum load

 

[Heiwa]

Heiwa:

I am a little confused..... we all agree that WTC 1 & 2 collapsed, right, .... well that means that "floors dropped down", right, ... But you claim that "there is no evidence that any floors dropped down". So what are you saying?

And as for buckling, .... let's say there was very little buckling, and the main mode of core column failure was fracture at the weld planes. That was possible "without any evil expeditious external energy input" wouldn't you say?

No - the floors dropped down first (cause) and the towers collapsed afterwards (effect). Why/how/when the floors dropped down (cause) is not known. Nist fantasy?

No - there is no such thing as very little buckling (unless you bump into someone's car at a supermarket parking with hysterical results). NIST has given up the official mass above 'buckled columns' idea and release of potential energy (cause) because the effect is ... no collapse.

Why would an assembly butt weld fracture in a lowly compressed column? What would cause that? Any details of this weld incl. location? It seems many welded connections failed ... but this was apparently long after collapse initiation; bolted floors suddenly falling down according NIST latest FAQ December 2007.

 

[Apollo20]

Einsteen/Heiwa:

I agree that collapse initiation is the key issue to be resolved in understanding the collapse. My energy transfer calculations were really only aimed at describing the energetics of the collapse itself using a simple model involving E1, "the energy needed to collapse one floor." I discussed the issue of how to calculate E1 in my paper because back when I wrote that paper I was struggling with ways to determine E1 and was happy to find any "guestimates" in the published literature. It was only later that I started to consider the tilting of the upper block as an important additional factor.

In the collapse initiation of WTC 2 we can clearly see the inward bowing of the east perimeter wall. I think this happened mainly because of the loss of horizontal bracing, as the trusses in the impact/fire-affected zone failed, than from the heating of the perimeter wall. Anyway, the bowing ultimately led to the east perimeter wall failure and allowed the upper block to tilt by tan^-1 (3.7/64) = 3.3 degrees - which is a lot! I think it was this downward movement that caused core columns to fail at their weakest point -the weld planes.

 

[StoneRook]

Heiwa - went to your site and must say....

"wow"

You compare the collapse to a child jumping on a bed?

You suggest building a model of the WTC out of plwood and some metal, and use a "water tank" to simulate the upper WTC block?

Then put a "pan of diesel oil on fire to simulate the jet fuel?

Ouch - even as a layman to structural engineering, I can see all kinds of wrong with your test....

I don't remember seeing a vast tank of water in the WTC that covered the entire floor(s).

I don't remember seeing it covered in plywood!

You don't model the trusses, the hat truss, the inner core and outer wall being pulled in by the sagging floor, you simply build four poles to hold up a water tank, surround it with plywood, fill that space with debris and a pan of diesel oil, and catch it on fire....

Can you really state is an accurate test?

You have read the NIST report, right?

 

[rwguinn]

Heiwa - went to your site and must say....

"wow"

<<snip>>
Can you really state is an accurate test?

You have read the NIST report, right?

sure he can--he states it all the time.
that doesn't make it true--see ad Nauseam

and item 2:
Nope. reading is for people who don't have enough imagination to make stuff up on the spot.

 

[pomeroo]

No, the same applies to all columns. #501 is just an example. I write for children. To keep it simple.

You write for children in order to communicate with an audience of your intellectual peers.

 

[Tony Szamboti]

Heiwa:

I am a little confused..... we all agree that WTC 1 & 2 collapsed, right, .... well that means that "floors dropped down", right, ... But you claim that "there is no evidence that any floors dropped down". So what are you saying?

And as for buckling, .... let's say there was very little buckling, and the main mode of core column failure was fracture at the weld planes. That was possible "without any evil expeditious external energy input" wouldn't you say?

Dr. Greening, you say above that you believe it was downward movement which caused the core columns to fail at their weakest point, which was the welds. I believe they were really only more susceptible in shear and bending. I am wondering if you could flesh out the mechanism that you believe might be able to account for the weld planes to fail at the initiation.