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WTC7 and the girder walk-off between column 79 and 44

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But the evidence shows us that the impact did remove the fire proofing. You can see it falling to the ground in the videos. The white dust below the red arrows is mostly fire proofing.

[qimg]http://i995.photobucket.com/albums/af74/waypastvne/zUntitled-1_small.jpg[/qimg]

You can watch it drift off down wind and land it the streets.

Can you offer an alternative explanation for the dust covering the streets (after the impact but before the collapse) that we see in these photos ?

http://wtcdata.nist.gov/gallery2/v/...y+Street+8-51+9111011+from+zenaa_com.jpg.html

http://wtcdata.nist.gov/gallery2/v/...h+Street+8-50+9111007+from+zenaa_com.jpg.html

http://wtcdata.nist.gov/gallery2/v/...h+Street+8-50+9111008+from+zenaa_com.jpg.html

Of course, the aircraft impact would have dislodged fireproofing, just not at the 98th floor on the other side of the building and well above the debris field which was headed downward at 10.6 degrees starting between the 95th and 96th floors.

The details matter.
 
Of course, the aircraft impact would have dislodged fireproofing, just not at the 98th floor on the other side of the building and well above the debris field which was headed downward at 10.6 degrees starting between the 95th and 96th floors.

The details matter.

The impact dislodged marble tiles in the lobby. Why wouldn't the vibration of the impact dislodge other stuff all over the building? It's not like steel transfers vibrations extremely well... Oh wait.
 
The impossibility is that the debris was moving far too slowly and was at a much lower level than the 98th floor trusses, so it could not have removed the fireproofing there.
Ah, so your "impossibility" is a mere disagreement about a nitpicking detail. I should have figured that.


The NIST analysis just implies collapse after the south wall was allegedly pulled inward by the trusses. Do you care to explain how the failure of the south wall would effect a complete collapse, because NIST did not explain it?
NIST Did not? Then what is NCSTAR 1-6 Chapter 8, if not a detailed explanation of these reasons?
 
Of course, the aircraft impact would have dislodged fireproofing, just not at the 98th floor on the other side of the building and well above the debris field which was headed downward at 10.6 degrees starting between the 95th and 96th floors.

The details matter.

For a person who thinks nothing of ignoring the largest fireballs most of us will ever see, that's a pretty hypocritical statement.
 
NIST claims, in the case of the towers, that the fires were an issue only when coupled with the removal of fireproofing. They even said if the fireproofing wasn't removed the buildings would still be standing.

Well the fireproofing could not have been removed where they said it was, due to the debris field velocity and position, so here we have another impossibility.

Utter nonsense.

In the investigation of the Sight & Sound Theater collapse (by fire), investigators found that the hammering of construction crews repairing floors caused spray on fire proofing to dislodge from joists below the floor.

FEMA report USFA-TR-097 said:
The two theater employees told the State Police Fire Investigator that when they first discovered the fire they noticed that the sprayed-on fire proofing had been knocked off the underside of the stage floor bar joists and support steel. The fire proofing was hanging on the wire mesh used to hold the coating to the overhead. The investigation revealed that the construction company’s removal of the stage floor covering down to the corrugated decking involved striking the floor hard enough to knock off the sprayed-on protection, exposing the structural steel and bar joists in the storage area.

Second fact: brittle substances that are form fit (i.e., sprayed on, painted on, molded to, etc.) onto ductile members invariably crack (& frequently dislodge) when the support member is flexed to any significant degree.

This effect is exactly why brittle marble & concrete structures on the first floor dislodged when the airplanes struck. The steel flexed, and the marble could not. And the 99% probability for the reports of "bombs in the basement, IMO. (BTW, the probability of actual "bombs in the basement" = 0%. Not approximately 0%. Exactly 0%.)

The towers, within about 10 stories of the impact, suffered an incredible dynamic loading and associated flexing of the support structure. The impulse at the collision floors was enormous, trying to push those floors in the direction of impact.

The resisting forces generated by inertia of the building above & below the impact floors was likewise enormous.

The stresses & flexure of the members between the impact floors & the adjacent (above & below) floors would likewise have been massive.

Far greater, I STRONGLY suspect, than a bunch of construction workers banging with hammers.

Your assertion that it is not possible for an impact of floor X to have dislodged insulation of floors X+1, X+2, etc. is just another baseless and in this case, laughable, assertion.

tk

PS. Your assertion that you know exactly where the collapse started is also unsupported. What you may know is "on what floor the collapse first manifest itself on the outside of the building."
 
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Despite my personal fear of having to work on something he designed, Tony is probably a good engineer. His troubleshooting skills, OTH, definitely could use improvement.

Try to remember this song Tony: "The ankle bone is connected to the... leg bone" (etc).
 
Despite my personal fear of having to work on something he designed, Xyz is probably a good engineer.....
(Direct reference to member removed)
Whether directed at any specific engineer or the class of 'most engineers' the measurement 'a good engineer' is probably too loosely defined.

My personal career experience has involved managing many engineers - at a guess in the order of 100 under my line management. Could be more.

I found that those engineers fell into different categories of competence of which three broad groupings will serve for the point I would make here.

1) The bottom level is those 'technician engineers' who can input the data into the text book or practice manual formula, spread-sheet, computer program etc and follow the lock step laid down procedures to arrive at the right answers.
2) The middle level is those who can derive new approaches, a different way of dealing with the same problem OR an innovative way of dealing with a new problem;
3) the top level is that minority group who can reason through a complex multi factor situation such as the challenge of forensic engineering represented by the WTC1, 2 &7 collapses.

Most engineers fall into groups 1 and 2 PLUS the reality of their occupation is that most of the work they need to do falls into group one level. i.e. routine application of standard methods.

And, in the sort of work scenario most of them occupy, it is rare for shortcomings of those people who are limited to the reasoning skills level of 'Group 1' to be exposed without the protection of work colleagues noticing and helping them through their errors.

And, as a manager, I really appreciated the handful of level three types that passed through my oversight on their way to bigger things.

Two disclaimers are relevant:
A) The 'level of competence' is not a single factor - there are multiple aspects - I have only presented it as one factor for simplicity of explanation; AND
B) Naturally the same sort of issue applies in other professions - but this forum and these topics tend to expose the weaknesses of engineering reasoning skills. And related areas of reasoning by applied physicists.

So the question of 'is Xyz a "good Engineer"?' has, IMO, to be put in a context. The context being 'good for what?' I'm sure that most of the engineers we see posting outrageously 'out of their depth' on these WTC collapse level 3 topics would be perfectly 'good engineers' when engaged on routine predefined tasks. i.e. level one work. Possibly at 'level 2' work. But clearly lost on these WTC 9/11 collapse level three plus complexities.

And, final comment, just like the truism that we cannot see our own blind-spots, the level 1 engineers are almost certainly not able to comprehend either level 3 problems OR WTF I've just written. :con2: ;)

Now go back over posts and ask 'Does the material posted by member "Pqr" demonstrate understanding at level 3 or 2 or 1?'

And smile at how I avoided MA problems by referring to the posted material - not the person who posts it. :rolleyes:
 
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Utter nonsense.

In the investigation of the Sight & Sound Theater collapse (by fire), investigators found that the hammering of construction crews repairing floors caused spray on fire proofing to dislodge from joists below the floor.



Second fact: brittle substances that are form fit (i.e., sprayed on, painted on, molded to, etc.) onto ductile members invariably crack (& frequently dislodge) when the support member is flexed to any significant degree.

This effect is exactly why brittle marble & concrete structures on the first floor dislodged when the airplanes struck. The steel flexed, and the marble could not. And the 99% probability for the reports of "bombs in the basement, IMO. (BTW, the probability of actual "bombs in the basement" = 0%. Not approximately 0%. Exactly 0%.)

The towers, within about 10 stories of the impact, suffered an incredible dynamic loading and associated flexing of the support structure. The impulse at the collision floors was enormous, trying to push those floors in the direction of impact.

The resisting forces generated by inertia of the building above & below the impact floors was likewise enormous.

The stresses & flexure of the members between the impact floors & the adjacent (above & below) floors would likewise have been massive.

Far greater, I STRONGLY suspect, than a bunch of construction workers banging with hammers.

Your assertion that it is not possible for an impact of floor X to have dislodged insulation of floors X+1, X+2, etc. is just another baseless and in this case, laughable, assertion.

tk

PS. Your assertion that you know exactly where the collapse started is also unsupported. What you may know is "on what floor the collapse first manifest itself on the outside of the building."

You are trying to say all of the fireproofing within 10 floors of the impact would have possibly been shaken loose due to the acceleration generated by the aircraft impact. That means you understand that there was no chance for the debris field moving downward from the impact at the 95th and 96th floors to have any chance of reaching the 98th floor on the other side of the building (and we do know the collapse initiated at the 98th floor in the North Tower).

The problem for your theory is that NIST didn't go that way as they did no test to show what you are saying. They only did debris blast testing on steel coated SFRM. They might have mentioned acceleration and vibration, but they did no testing to show it was possible. When you want to prove something in engineering you do a test.

SFRM has very low mass and the force on its bond would have only been F = ma where "m" was its mass and "a" the acceleration of the building due to the impact. It is quite unlikely that the SFRM would have dislodged all the way on the other side of the building and that is why NIST did not test a specimen on a shaker to prove it.
 
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Ah, so your "impossibility" is a mere disagreement about a nitpicking detail. I should have figured that.



NIST Did not? Then what is NCSTAR 1-6 Chapter 8, if not a detailed explanation of these reasons?

NCSTAR 1-6 just tries to say the core was thermally weakened. It does not provide a substantiated analysis for that statement. Additionally, it does not provide any substantiation for overload and failure of the east and west perimeter wall columns, which had a factor of safety against gravity loads of 5.00 to 1. The NIST load redistribution on the perimeter is at worst about 30% more than what was normally on the columns which was about 20% of their capacity. So here we have 1.3 x 20% = 26% of their capacity. In that case the columns would have still had a factor of safety of just under 4.00 to 1. So NCSTAR 1-6 Chapter 8 does not explain the collapse propagation across the entire building emanating from the south wall, and interestingly Dr. Bazant picks up after the upper section is already falling.

So we have this big hole in the official story where nobody explains how a south wall failure could cause a propagation across the building. That is why I asked you to try and explain it. If you really think it was a natural occurrence you should be able to do that.
 
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... Just checking in to see if you decided to make educated guesses on the collapses based on ALL the variables yet. Guess not. I'll check back later, but I won't hold my breath.

But I do have one question, is the walk off scenario in your world something that happened gradually, or not?
 
Anyone forgetting that the core was also fire-proofed with gypum wall board, which doesn't require all that much force to completely shatter to pieces and isn't affixed to the structure as an adhesive?
 
Anyone forgetting that the core was also fire-proofed with gypum wall board, which doesn't require all that much force to completely shatter to pieces and isn't affixed to the structure as an adhesive?

No, in the case of gypsum board on the columns you would have to hit it to knock it off.

Can you tell us how the debris field heading downward at 10.6 degrees from the impact at the 95th and 96th floors could have done this?
 
No, in the case of gypsum board on the columns you would have to hit it to knock it off.

Can you tell us how the debris field heading downward at 10.6 degrees from the impact at the 95th and 96th floors could have done this?

Vibration, overpressure from the fireball, the sudden massive sway, IT KNOCKED THE TILES DOWN! How can you ignore that???
 
No, in the case of gypsum board on the columns you would have to hit it to knock it off.

Can you tell us how the debris field heading downward at 10.6 degrees from the impact at the 95th and 96th floors could have done this?

Goddamit Tony!

The whole buildings shook violently, and there was a HUGE FIREBALL FIFTEEN FRIGGIN STORIES HIGH INSIDE AND OUT!


GET A NEW HOBBY!
 
Goddamit Tony!

The whole buildings shook violently, and there was a HUGE FIREBALL FIFTEEN FRIGGIN STORIES HIGH INSIDE AND OUT!


GET A NEW HOBBY!

Seriously. It knocked the lobby all to hell. Why on Earth would you expect anything to survive undisturbed within a few floors either way of the impact regardless of angle?
 
No, in the case of gypsum board on the columns you would have to hit it to knock it off.

Can you tell us how the debris field heading downward at 10.6 degrees from the impact at the 95th and 96th floors could have done this?
The building was hit by a large aircraft... The aircraft did serious damage on it's way in... The building moved when it was hit.... a lot. It flexed... a lot. The structure was elastic enough to handle that. Brittle materials like dry wall, and marble don't handle it so well. They're not made for that... Debris impact is one thing... but it was never by itself :\
 
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Seriously. It knocked the lobby all to hell. Why on Earth would you expect anything to survive undisturbed within a few floors either way of the impact regardless of angle?

Take a look at the photo of how columns are fireproofed with gypsum on page 340 of this U.S. Gypsum document http://www.usg.com/documents/construction-handbook/chapter10.pdf.

They are supported by a frame around the column. The aircraft impact acceleration was high at the exterior wall but it was attenuated by the failing columns and floors as well as the aircraft breaking up. It could not generate enough acceleration at the core to cause the gypsum framing to come off the core columns.
 
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The building was hit by a large aircraft... The aircraft did serious damage on it's way in... The building moved when it was hit.... a lot. It flexed... a lot. The structure was elastic enough to handle that. Brittle materials like dry wall, and marble don't handle it so well. They're not made for that... Debris impact is one thing... but it was never by itself :\

If you try putting some numbers to it instead of just saying the building was hit by a large aircraft you might understand what I am saying.
 
If you try putting some numbers to it instead of just saying the building was hit by a large aircraft you might understand what I am saying.

You want numbers, we got numbers, 25, 20034, 64, 42.

There you go.

(These numbers have as much relevance to the collapse of WTC7 as your post does.)
 
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