Failure mode in WTC towers

[GregoryUrich]

Excellent work MT. A truly amazing phenomenon.

 

[DGM]

Excellent work MT. A truly amazing phenomenon.

Gravity never ceases to amaze.

 

[Newtons Bit]

Dave comments:



Yes. Norseman asked a similar question when curioso number 3 was introduced. I referred him to photo libraries that show the same column sections were in the same place while firemen were walking around in an understandably dazed state on 9-11-01. He understood and admitted my claim of the original locations and states of these column sections was indeed correct.

There are many photos of these same column sections, always in the exact same location, in the following 2 albums.

http://www.sharpprintinginc.com/911...p=view&PHPWS_Album_id=12&MMN_position=102:102

http://www.sharpprintinginc.com/911...p=view&PHPWS_Album_id=27&MMN_position=139:139

Many, many photos of the same column sections, some of which were taken on 9-11.

The spacings of the mechanical room floors relative to typical office flooring are distinctive. I reproduce curioso number 3 below for easy reference.




NB, once again thanks for your efforts to create a model. This model needs to be tested by seeing whether it is consistent with observed phenomena.

I personally cannot see how your model can explain the observed phenomena mentioned in curiosos 3 and 5, but I will await your explanation with interest.


If they are inconsistent, which do you abandon, your model or the observed phenomena?

I have not provided a model, I have provided an explanation as to why columns that fail in axial compression will break at their weld-planes prior to any large amounts of bending along their length. I have debunked someone elses model, but I have not provided one of my own.

Now you ask me if I want to abandon the observed phenomena in favor of a model that doesn't exist? Sir you go to far. I have stated, repeatedly, that we only paint the collapse in broad strokes. This is because it is a chaotic event and it is impossible to create a model that is solvable by hand (and not a supercomputer) that can generate such results. What do you expect us to do? Generate a model that says "75% columns failed in axial compression, 12 large sheets of columns of 8x9 columns broke away together, 10% columns failed in bending" or something? We do not have the mathematics to do that. Stop asking for it.

This is a chaotic event. Many different failure modes are present. Do not ask for "the one" event that describes them all, it doesn't exist. It should be obvious that it doesn't.

 

[Norseman]

Curiouso Number 4: Characteristics of Collapse Initiation and Progression Along The East Face of the South Tower.

The only perimeter portions seen being pulled inward on the South Tower were along this face. It can be seen in the following clip:

South Tower Stabilized. NBC High Quality South Tower Collapse. High quality stabilized video of the east face, floors 75 to 85, at the moments of collapse initiation. The camera then zooms out to capture the ejection patterns along the collapse front of the east face.
http://www.youtube.com/watch?v=a7e79Tjt5Gk&feature=related


The inward pulling was a rather fast process. It is immediately followed by a rather forceful OUTWARD pushing. Please recall that curiouso number 3 notes that the mechanical room perimeter column sections just under the collapse initiation point were discovered unbucked, speared into the earth and were some of the furthest displaced perimeter sections found to the east.

Contradiction: If these perimeter sections were seen being pulled inwards during collapse initiation, why were the perimeter sections just below them found to be some of the farthest displaced sections from the footprint?

If they were being pulled inwards, this means that they were being pulled in by flooring that was still firmly attached.

Major Tom, that video you posted debunks your whole idea of the perimeter columns outside the mechanical equipment rooms on floor 75 and 76 being pulled in. I think you should review that video again very, very carefully.

 

[Max Photon]

On WTC2's impaled mechanical floor panels

[snip] Contradiction: If these perimeter sections were seen being pulled inwards during collapse initiation, why were the perimeter sections just below them found to be some of the farthest displaced sections from the footprint? [snip]

Major Tom,

I do not see the contradiction.

When WTC2's east face floors 81 and 82 bowed inward and failed at the columns splices, the east face panels from the upper block went behind the east face panels of the lower block.

There was an avalanche inside the chute, which created the collapse front dust ejections.

Then the east face panels from the lower block fell outward in a large section that included the upper mechanical floor panels. Because these panels were at the top of the section falling away, they were displaced the farthest from the base of the tower.

And because the horizontal row of upper mechanical floor panels were heavier, stronger, and welded at the column splices, it makes sense that a multi-panel section should stay intact even after falling 75 stories.

Max

 

[Heiwa]

Is that a figure of speech, or have you actually approached NIST?

Dave

From: Anders Björkman
To: sunder@nist.gov ; Richard Kayser <richard.kayser@nist.gov >

Sent: Tuesday, January 15, 2008 9:31 PM
Subject: NIST report NISTNCSTAR1-6D.pdf - WTC1/2 global collapses


Hallo Shyam and Rich.

I have updated my article for children at http://heiwaco.tripod.com/nist.htm and http://heiwaco.tripod.com/nist1.htm and would be much obliged to receive conclusions and comments and corrections. Thanks.

Best regards

Anders Björkman

 

[Heiwa]

So, large masses of moving water cannot damage steel structures? Are you certain of that? Never seen it happen, in your 40 years of professional experience?

Your 33,000 tons of water is an eight meter deep layer over the area of an entire floor. "Dropped" on the floor below, it would deliver an enormous impulse. (Of course, if you poured it out a little at a time, it would do no great damage. But that's irrelevant; you're comparing it to the impact of the upper structure which was all at once.) Changing the direction of all that water so that it spills off the sides would require a lot of force. I think the structures, especially the floors, could not exert sufficient force and instead would fail, so the water would keep moving downward, collapsing the tower. You'd have to show calculations to convince me that the structure could withstand it. Handwaving won't do it.

Respectfully,
Myriad

You imply an impact between water and a structure. I am quite good at that! Waves hitting moving ships in a seway! But actually the wave is not really hitting the ship!! Surprised. The wave generally moves up/down and the ship moves quickly into it. And there is an impact! BOOM! Actually it is air trapped between the wave and the ship surface that compresses to say 10 bar and then 'explodes'. Big splash and the water flies away in all directions! The energy involved is the compressed air and apart from splashing away the water (backwards, sideways) it may cause plastic deformation of the steel plate hull panel inwards where the high air pressure was applied. That's how it works. Same would happen with the WTC1 I assume. Big splash! Only the upper floor may be deformed/damaged and that's it.

You can try it actually. Fill a thin rubber ballon with water and drop it on a solid surface. Children like it.

 

[Furcifer]

Waves hitting moving ships in a seway!

Bolding mine, for a reason.

Same would happen with the WTC1 I assume. Big splash! Only the upper floor may be deformed/damaged and that's it.

You know what they say about assuming...

 

[Heiwa]

No, Heiwa. I posted a full fledged 3d Finite Element Model. It has properly modelled fixed end offsets from column to beam which represent how the beam is attached to the side of the column. You do not need to model the sides of the column with seperate elements to do this. Single lines (elements) can represent a vast amount of information in FE, the fact that you don't understand this tells of your ignorance on the subject. And no, you haven't done this analysis for 40 years. 40 years ago FEM wasn't available to anyone except the airline industry, specifically in turbines and universities who were still trying to figure the concept out.

Explain to me again how a connection like the one below induces zero moment into the column:

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_16329479e2ead3ecb9.jpg[/qimg]

^That detail is similar (not exact) to what was at the WTC. You said it doesn't because it's pinned. Mr. Szamboti says it can't because the columns are fixed. At least one of the two of you must be wrong since you're arguing mutually exclusive concepts. Though in reality, you're both wrong. You just don't understand how buildings are put together, and he doesn't understand basic newtonian physics.

The picture shows a WTC floor truss with its upper part just bolted to a column, which is a pin joint where no bending moment can be transmitted. Had the truss been fitted with a real web plate and a flange connected to the column then the connection becomes fixed and can transmit bending.

When I do FEM analysis I also include beam elements (2 nodes) apart from plate elements (3+ nodes), etc. in the models. The nodes I can fix or allow to rotate, as required. No big deal. But it is still just a model. Reality is always different.

 

[Myriad]

You imply an impact between water and a structure. I am quite good at that! Waves hitting moving ships in a seway! But actually the wave is not really hitting the ship!! Surprised. The wave generally moves up/down and the ship moves quickly into it. And there is an impact! BOOM! Actually it is air trapped between the wave and the ship surface that compresses to say 10 bar and then 'explodes'. Big splash and the water flies away in all directions! The energy involved is the compressed air and apart from splashing away the water (backwards, sideways) it may cause plastic deformation of the steel plate hull panel inwards where the high air pressure was applied. That's how it works. Same would happen with the WTC1 I assume. Big splash! Only the upper floor may be deformed/damaged and that's it.

I don't see any calculations in your post. If you're quite good at this, then show me your calculation of the peak dynamic load that 33,000 tons of water dropped, say, 3 meters onto a wtc tower floor would exert, and then show me your calculation of how much force the floor can resist, so that I can see that the first number is less than or equal to the second.

But before starting that, tell me, when you build the hull of a large ship out of 4" of concrete on a 22-gauge (less than a millimeter thick) steel sheet, is it better for the concrete to be on the inside or the outside?

Silly question, of course. Assuming it didn't fracture and sink the moment it was launched, any such hull would crumble as soon as it hit one wave at ten knots or so. There's not much resemblance between a steel ship's hull and a wtc tower floor, as you already know. (That is, whether you're the expert you claim to be or not, you should know that much.)

Here's what moving water can do to a steel structure:

What steel am I talking about? There's no steel in the picture because the moving water broke it into pieces and washed those pieces downstream up to two miles. I'm sure there was plenty of water splashing and flying away in all directions, but that didn't save the bridge. (Bardsdale Bridge, 1928)

Respectfully,
Myriad

 

[Major_Tom]

NB explains:

I have not provided a model, I have provided an explanation as to why columns that fail in axial compression will break at their weld-planes prior to any large amounts of bending along their length.

Your explanation utilizes inward perimeter pulling. The perimeter, being on the outside of the building, is an observable object.

Yet the only major inward pulling observed was along the east face of WTC 2 along the elevation of collapse initiation.

Therefore, if your explanation has any substance it should be consistent with the entirety of observed phonomena seen in this region captured in photos and on video.

Do you wish to apply your explanation to this region? Wouldn´t this be the next natural logical step if you sincerely wished to know whether your explanation has merit?

If you avoid APPLYING your explanation by testing it against observed phenomena in this critical region, then it doesn´t seem to be relevent to the actual collapses under discussion.

And please note that concerning WTC 1 where much more limited inward pulling was observed and only along the east side of of the south face, your diagram doesn´t seem to be applicable at all.

Where are we to APPLY the above diagram to twin towers?

It would seem the only place you can apply such an explanation is to WTC 2, east face.

Along this face we see a rather rapid inward pulling only along a single horizontal line. Does that match the explanation.

I am not following the multiple floor sagging.

I don´t see the ability for you to explain the 3 floor separation in the first 2 horizontal rows of forceful "dust" ejections.

I don´t see how your explanation accounts for the fact that the core column-to-column welds are separated by 3 floors.

I see no possible way your explanation for the floor-by-floor ejection patterns at the very leading front of the wave of "collapse".


Or please feel free to apply you explanation to any facade you wish on either of the buildings.

But please APPLY it to explain the recorded phenomena of actual buildings under discussion.

NB goes on to confess:

I have stated, repeatedly, that we only paint the collapse in broad strokes.

That is because, as I have mentioned repeatedly, if you try to apply your "painting" to actual details observed in these specific "collapses", you yourself will see that you explanations will fail miserably.

He goes on:

This is because it is a chaotic event and it is impossible to create a model that is solvable by hand (and not a supercomputer)

WTC 2, east face, floors 81 to, say 70. You have floors, perimeter and core. Not brain surgery. Only 3 general objects.

Pencil sketches, anything. Use a freakin' crayon, I really don´t care.

If you can´t commit to some collapse initiation and progression mechanism in this very limited region which matches observed phenomena then your act of hiding behind ambiguity will be seen to be wearing pretty thin.


Max and Norseman, I'll address your concerns in an upcoming post.

 

[Major_Tom]

NB says:

No, Heiwa. I posted a full fledged 3d Finite Element Model.

And to me:

I have not provided a model, I have provided an explanation as to why columns that fail in axial compression will break at their weld-planes prior to any large amounts of bending along their length.

?????????

 

[Major_Tom]

Max notes:

Major Tom,

I do not see the contradiction.

When WTC2's east face floors 81 and 82 bowed inward and failed at the columns splices, the east face panels from the upper block went behind the east face panels of the lower block.

There was an avalanche inside the chute, which created the collapse front dust ejections.

That is because you are a smart dude.

In your case let's not consider what I wrote as a contradiction but just as a description of the phenomena observed.

But doesn´t what you wrote beg the following questions:

Since the upper "block" was leaning over the east facade of the lower section, how did it get all the way inside there?

How does that correspond the the "dust" ejections observed: The first 2 more powerful horizontal rows skipping a few floors?

The bizarre ejection patterns seen along the northeast corner? Note that some of these ejections skipped floors along this corner and LATER, after the leading edge of the "collapse" front has passed, you see ejections along the corner on the very floors skipped.

Max, to my knowledge only Norseman even attempted to explain how the upper "block" perimeter sections "sheared" the floors from the lower "block" perimeter along this facade.

Of course this seems inconsistent with the "piston effect" that will be needed to explain the forceful ejections seen leading the way in the observed "collapse" wave. For that the idea of pancaking will need to be introduced by someone who believes in the OCT.

Norseman, since you put much work into your previous explanation, if you wish to simply "cut and paste" it here for the others to see rather than retyping it, such a reply would work for me.

 

[Norseman]

You imply an impact between water and a structure. I am quite good at that! Waves hitting moving ships in a seway! But actually the wave is not really hitting the ship!! Surprised. The wave generally moves up/down and the ship moves quickly into it. And there is an impact! BOOM! Actually it is air trapped between the wave and the ship surface that compresses to say 10 bar and then 'explodes'. Big splash and the water flies away in all directions! The energy involved is the compressed air and apart from splashing away the water (backwards, sideways) it may cause plastic deformation of the steel plate hull panel inwards where the high air pressure was applied. That's how it works. Same would happen with the WTC1 I assume. Big splash! Only the upper floor may be deformed/damaged and that's it.

Damage done by a rouge wave, original context. More in Wikipedia here.

By the way 10 bar = 101 971,62 kg/ square meter.

 

[Newtons Bit]

NB says:



And to me:



?????????

Is this the sum of truther knowledge? Can you really not understand the difference between a FEM of a simple concept and a collapse model?

Heiwa and Realcddeal can't figure out how a load applied to the face of a column produces a moment. You can't figure out what a model is.

 

[Tony Szamboti]

Is this the sum of truther knowledge? Can you really not understand the difference between a FEM of a simple concept and a collapse model?

Heiwa and Realcddeal can't figure out how a load applied to the face of a column produces a moment. You can't figure out what a model is.

Talk about taking things out of context. I said the moment would be removed from the column due to an opposing force and counteracting moment from the adjacent beams.

 

[WildCat]

This is a chaotic event. Many different failure modes are present. Do not ask for "the one" event that describes them all, it doesn't exist. It should be obvious that it doesn't.

If truthers were able to grasp the obvious there would be no need for this subforum.

 

[Newtons Bit]

Talk about taking things out of context. I said the moment would be removed from the column due to an opposing force and counteracting moment from the adjacent beams.

Okay.

Correction to my post above, Realcddeal doesn't understand what a fixed connection in a frame means and thus doesn't understand this problem.

 

[Heiwa]

I don't see any calculations in your post. If you're quite good at this, then show me your calculation of the peak dynamic load that 33,000 tons of water dropped, say, 3 meters onto a wtc tower floor would exert, and then show me your calculation of how much force the floor can resist, so that I can see that the first number is less than or equal to the second.

It doesn't work like that! The water does not impact the hard surface (or vice versa). Air (not a very rigid body) is trapped between the hard surface and the water and compressed to say 10 bar and then the air 'explodes' - that is the observed impact - and the water splashes in all directions. I have measured the pressures involved! If there is no impact, the water is just pushed to the side.

What happens when a lot of rubble (many material parts and bodies of various stiffness) impacts onto a wtc tower floor from above is another matter. I assume the rubble compacts, but it must also be pushed to the side. Both effects take time and consume energy and cannot be regarded as an instant impact that overloads the floor.

Rather a fast build-up of rubble takes place on the wtc tower floor that might be overloaded. The floor will then break in one location; at the side or in the middle, and become sloping and the rubble will flow along the slope, e.g. out of the building or through a hole in the floor and probably get stucked there = the collapse is arrested.

All these ideas that a rigid mass suddenly impacts an initiation zone in the wtcs and creates a crush zone is just fantasy. Rubble do not behave like that.

 

[funk de fino]

It doesn't work like that! The water does not impact the hard surface (or vice versa). Air (not a very rigid body) is trapped between the hard surface and the water and compressed to say 10 bar and then the air 'explodes' - that is the observed impact - and the water splashes in all directions. I have measured the pressures involved! If there is no impact, the water is just pushed to the side.

What happens when a lot of rubble (many material parts and bodies of various stiffness) impacts onto a wtc tower floor from above is another matter. I assume the rubble compacts, but it must also be pushed to the side. Both effects take time and consume energy and cannot be regarded as an instant impact that overloads the floor.

Rather a fast build-up of rubble takes place on the wtc tower floor that might be overloaded. The floor will then break in one location; at the side or in the middle, and become sloping and the rubble will flow along the slope, e.g. out of the building or through a hole in the floor and probably get stucked there = the collapse is arrested.

All these ideas that a rigid mass suddenly impacts an initiation zone in the wtcs and creates a crush zone is just fantasy. Rubble do not behave like that.

Why does it get wet then?

Tipping floors and flowing rubble? You are getting more ridiculous by the minute and, as I said earlier, spoiling these threads