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

[MarkLindeman]

Enik's FEA work is impressive. I would expect it to be correct within the context of boundary assumptions. It is the boundary assumptions I am not sure about at this stage....

And I still wait for your RIGHT assumptions, boundary conditions, or other factors. Maybe I missed them in a previous post. Can you please list them out?

I'm in no position to speak for ozeco41, but if he is not sure about the boundary conditions at this stage, I doubt he can enumerate the correct ones.

It strikes me as legitimate, respectful, and honorable to say that one is impressed with someone else's work but cannot tell whether it is correct. That's often at least my initial response to a research paper.

 

[ozeco41]

...It strikes me as legitimate, respectful, and honorable to say that one is impressed with someone else's work but cannot tell whether it is correct. That's often at least my initial response to a research paper.

...Correct -- and it was my initial response -- see my next comment.

I'm in no position to speak for ozeco41, but if he is not sure about the boundary conditions at this stage, I doubt he can enumerate the correct ones...

The false assumptions I refer to flow from Tony Szamboti's claim and are two (Or two groups of assumptions which combine into those two). I have defined them clearly on several occasions in this tread. They are:

1) The technical assumption made by Tony that the columns 79 and 44 did not change their relationship to the beam which allegedly walked off. That assumption means that Tony and many others assumed that the distance between the columns was unchanged. That assumption is most probably false BUT could be true if all the changing forces impacting on the columns cancelled out. An unlikely circumstance which I spelled out on glorious detail in an earlier post; AND

2) The logical assumption by Tony that he does not bear burden of proof to support the technical assumption in order to make his claim.

Only the first or technical issue is relevant to Enik and I have clearly said that I do not know if he has adequately addressed it. It is not my burden to complete his claim for him.

Put as simply as I can, given that I have not yet examined Enik's latest effort, has Enik ensured that his analysis accommodates all of the stress redistributions that occurred so that he has overcome the "no movement or changes to Col79/Col44" false assumption.

Final comment it is Enik's claim I am addressing and no way will I accept the multiple attempts to press me to do the work. I have offered a comment. If Enik does not wish to respond to that comment so be it. I will not accept "reverse burden of proof" however disguised.

 

[enik]

...It strikes me as legitimate, respectful, and honorable to say that one is impressed with someone else's work but cannot tell whether it is correct. That's often at least my initial response to a research paper.

Which is precisely why all of this should be posted over at the 911freeforums instead of here. Ozeco41's excuse not to go chasing after Tony into a forum, taking refuge among his friends (although he is criticized quite harshly by femr2) is no different than ozeco41 taking refuge over here.

Ozeco41, if there is something I can analyze with your "...the columns 79 and 44 did not change their relationship to the beam..." argument, I would be more than happy to do so.

 

[Major_Tom]

Ozeco: "Final comment it is Enik's claim I am addressing and no way will I accept the multiple attempts to press me to do the work. I have offered a comment."

I haven't seen you do any work over the last 2 years. Instead, you seem to make declarations and then claim they are "good enough".

The standard used when declaring when something is good enough seems to come from your feelings, which is then declared to be "good enough".


Zero follow-up research.

 

[Tony Szamboti]

...Correct -- and it was my initial response -- see my next comment.

The false assumptions I refer to flow from Tony Szamboti's claim and are two (Or two groups of assumptions which combine into those two). I have defined them clearly on several occasions in this tread. They are:

1) The technical assumption made by Tony that the columns 79 and 44 did not change their relationship to the beam which allegedly walked off. That assumption means that Tony and many others assumed that the distance between the columns was unchanged. That assumption is most probably false BUT could be true if all the changing forces impacting on the columns cancelled out. An unlikely circumstance which I spelled out on glorious detail in an earlier post; AND

2) The logical assumption by Tony that he does not bear burden of proof to support the technical assumption in order to make his claim.

Only the first or technical issue is relevant to Enik and I have clearly said that I do not know if he has adequately addressed it. It is not my burden to complete his claim for him.

Put as simply as I can, given that I have not yet examined Enik's latest effort, has Enik ensured that his analysis accommodates all of the stress redistributions that occurred so that he has overcome the "no movement or changes to Col79/Col44" false assumption.

Final comment it is Enik's claim I am addressing and no way will I accept the multiple attempts to press me to do the work. I have offered a comment. If Enik does not wish to respond to that comment so be it. I will not accept "reverse burden of proof" however disguised.

Ozeco, you have yet to provide one iota of a basis for your claim that the relationship between columns 44 and 79 could have been changed and have no business saying my assumption here has been shown to be improper or incorrect.

NIST didn't bring up anything in this regard, and they did a finite element model and fire simulation of the entire building. If something had happened, like what you are wildly postulating, that would have helped their case for collapse due to fire, they would have.

 

[beachnut]

Ozeco, you have yet to provide one iota of a basis for your claim that the relationship between columns 44 and 79 could have been changed and have no business saying my assumption here has been shown to be improper or incorrect.

NIST didn't bring up anything in this regard, and they did a finite element model of the entire building. If something had happened, like what you are wildly postulating, that would have helped their case for collapse due to fire, they would have.

Published yet? What will you do when you realize your CD claims are bogus?

 

[Tony Szamboti]

Published yet? What will you do when you realize your CD claims are bogus?

It is a shame you haven't been able to prove that to me. I actually wish you could.

 

[beachnut]

It is a shame you haven't been able to prove that to me. I actually wish you could.

The CD theory is a fantasy. You can't prove your fantasy:I have proved it to you, you are not paying attention. But fell free to publish your proof of CD now. Was Flt 93 CD too? 77?

Collapse due to fire for WTC 7.

When is the published date for that letter thing?

 

[femr2]

Which is precisely why all of this should be posted over at the 911freeforums instead of here. Ozeco41's excuse not to go chasing after Tony into a forum, taking refuge among his friends (although he is criticized quite harshly by femr2) is no different than ozeco41 taking refuge over here.

What criticism are you referring to ?

 

[Oystein]

Ozeco, you have yet to provide one iota of a basis for your claim that the relationship between columns 44 and 79 could have been changed ...

May I help oz out here? Ok:

The building suffered from severe, wide-spread fires on many floors for several hours and had been shown (by achimspok, femr2; anecdotally by FDNY engineers) to have been moving in its entirety long before the "fast" final 18 seconds of its collapse. Therefore, it is reasonable to consider the significant probability that the structural geometry in the final minutes differed significabtly from the "as-build" geometry.​

There.
That was easy

 

[Tony Szamboti]

May I help oz out here? Ok:

The building suffered from severe, wide-spread fires on many floors for several hours and had been shown (by achimspok, femr2; anecdotally by FDNY engineers) to have been moving in its entirety long before the "fast" final 18 seconds of its collapse. Therefore, it is reasonable to consider the significant probability that the structural geometry in the final minutes differed significabtly from the "as-build" geometry.​

There.
That was easy

No it isn't that easy. Ozeco, and anyone who agrees with him, needs to provide the actual mechanisms for what he is claiming. Just saying the whole building was swaying or was on fire and that this produced forces and mechanics supporting what you are saying is farcical. You can give rough estimates but you need to be specific about how certain forces would have developed and the mechanics that would have been involved to cause column to column relationship changes.

 

[Oystein]

No it isn't that easy. Ozeco, and anyone who agrees with him, needs to provide the actual mechanisms for what he is claiming. Just saying the whole building was swaying or was on fire and that this produced forces and mechanics supporting what you are saying is farcical. You can give rough estimates but you need to be specific about how certain forces would have developed and the mechanics that would have been involved to cause column to column relationship changes.

Well, I can't do this in such detail.
But that doesn't mean that it isn't an absolute certain fact that the geometry of the building's structure was compromised and not in its as-built state.

I can't say for certain for example that the distance between columns 44 and 79 was significantly different from specification by the time the girder experienced thermal expansion or contraction, but likewise you can't assume that it wasn't because, again, the mere fact that there were fires, as well as the outside observations, establish as 100% certain fact that SOME distances between members weren't anymore what they were supposed to be.

 

[LSSBB]

Well, I can't do this in such detail.
But that doesn't mean that it isn't an absolute certain fact that the geometry of the building's structure was compromised and not in its as-built state.

I can't say for certain for example that the distance between columns 44 and 79 was significantly different from specification by the time the girder experienced thermal expansion or contraction, but likewise you can't assume that it wasn't because, again, the mere fact that there were fires, as well as the outside observations, establish as 100% certain fact that SOME distances between members weren't anymore what they were supposed to be.

+1.

There are several probability distributions involved here. That is much of the reason why a linear geometric approach cannot disprove a fire induced collapse.

 

[enik]

The building suffered from severe, wide-spread fires on many floors for several hours and had been shown (by achimspok, femr2; anecdotally by FDNY engineers) to have been moving in its entirety long before the "fast" final 18 seconds of its collapse. Therefore, it is reasonable to consider the significant probability that the structural geometry in the final minutes differed significabtly from the "as-build" geometry.

How does this change the assumptions and how will it affect the outcome in the FEA?

What criticism are you referring to ?

It had to do with the missing jolt some time ago.

 

[ozeco41]

Ozeco, you have yet to provide one iota of a basis for your claim that the relationship between columns 44 and 79 could have been changed and have no business saying my assumption here has been shown to be improper or incorrect.

NIST didn't bring up anything in this regard, and they did a finite element model and fire simulation of the entire building. If something had happened, like what you are wildly postulating, that would have helped their case for collapse due to fire, they would have.

May I help oz out here? Ok:

The building suffered from severe, wide-spread fires on many floors for several hours and had been shown (by achimspok, femr2; anecdotally by FDNY engineers) to have been moving in its entirety long before the "fast" final 18 seconds of its collapse. Therefore, it is reasonable to consider the significant probability that the structural geometry in the final minutes differed significabtly from the "as-build" geometry.​

There.
That was easy

Tony is being obtuse - whether deliberately or not does not matter.

I will try for what should be the last time to express this simply:

There are two issues which are relevant:
1) The technical issue which in my criticism of Tony's claim is his assumption that the spacing between Col79 and Col44 was unchanged. Either in distance OR on applied forces which would change the distance is constraints changed. Tony assumes "unchanged" and his claim rests on that assumption. (BTW as an aside many members responding have also accepted the assumption whether or not they realised that they were doing so.)

2) Burden of proof. Tony assumes "unchanged" in a building that has been subject to wide ranging fire effects. It is his burden to demonstrate that his assumption is warranted. It is not my burden to prove that his assumption is false.

He has not supported his assumption so the status of his claim is "unproven" - put scientific words around that if you wish - I cannot be bothered.

Now Tony attempts the standard truther trick of getting me to accept reversed burden of proof. I am challenged to prove the opposite claim to Tony's.

Many things wrong with that.

The engineering reality is that it is highly unlikely that anyone could prove OR disprove the assumption with certainty. And I detailed the reasons in my earlier posts which, true to style, Tony chooses to ignore. BUT the probability is heavily weighted TOWARDS "must have changed". In a steel framed building through which fires had raged the idea that the spaces and constraints around one member would be unchanged is near zero. There is the remote possibility that all the changes could cancel out to produce a net zero effect. Repeating for emphasis of those who still miss the three key points:
1) I doubt it can ever be known what the true situation was; AND THEREFORE
2) Tony's claim rests on an unsupportable assumption. He may be right but he cannot demonstrate it. Nor can anyone demonstrate that the technical claim is wrong. The probability is strongly that he is wrong on the assumption. AND
3) THEREFORE his claim is not made/proven/demonstrated. And that is what I have said repeatedly.

The logical/procedural error is the one which dominates. Tony cannot support his claim.

AND it is not my job to build a counter claim to help Tony create his desired false dilemma - "ozeco cannot prove the alternate THEREFORE Tony Szamboti is right."

Enik initially followed the same technical limit, then expanded his technical boundary but is still tending to follow the procedural error.

analogies don't compute well on JREF BUT

Me: "Hey, I don't want to buy this car, it has no engine."

Car Salespersons T and E "You are wrong - build an engine to prove this car doesn't have one."

 

[Oystein]

[1] How does this change the assumptions [2] and how will it affect the outcome in the FEA?
...

[1] When looking at the local situation at and immediately around column 79, it has been asserted that Tony assumes the distance between columns 79 and 44 was unchanged by events before and/or away from this local situation, and Tony has not denied this assumptions and maintained it is valid, and any differing assumption must be proven, while his can stand unproven. At least that's my reading of recent exchanges. The presence of long-time, wide-spread fires, and the observation of a moving building, both suggest that we can't rule out one assumption or its opposite (and if we allow for a changed distance, it can go in several directions).

[2] How can I know? But Tony isn't talking about a FEA, or is he?
I would think that, in an ideal world, one would have to run a million FEAs, each time with slightly differing assumptions within a set of possible assumptions. I would guess that some such simulations would leave the girder attached to column 79 and no collapse, some would see the girder detach but still no collapse, some would show the girder stay attached and collapse originate elsewhere, and some would see the girder detach but collapse originate elsewhere.

 

[ozeco41]

How does this change the assumptions and how will it affect the outcome in the FEA?....

[1] When looking at the local situation at and immediately around column 79, it has been asserted that Tony assumes the distance between columns 79 and 44 was unchanged by events before and/or away from this local situation, and Tony has not denied this assumptions and maintained it is valid, and any differing assumption must be proven, while his can stand unproven. At least that's my reading of recent exchanges. The presence of long-time, wide-spread fires, and the observation of a moving building, both suggest that we can't rule out one assumption or its opposite (and if we allow for a changed distance, it can go in several directions)....

Just a minor point - but another aspect which most members have missed/ignored. Notice I was careful to state "...the spacing between Col79 and Col44 was unchanged. Either in distance OR in applied forces which would change the distance if constraints changed." The heat affects on the frame could (and most probably did) introduce stresses which would tend to change the gap HOWEVER the attached girder would hold the Col79-Col44 spacing unchanged until the connections broke. That introduces further complications which AFAICS everyone has been overlooking. The situation ain't as simple as most people have represented it.

...[2] How can I know? But Tony isn't talking about a FEA, or is he?...

It matters not. Tony has made a claim. That claim relates to certain loading and spatial characteristics of a steel frame. FEA is a method of quantifying those matters. BUT it is only as good as the context and assumptions it is applied to. My comments directed at "context and assumptions". Most of the discussion has not used FEA - just simple linear expansion and sag calcs. I have not criticised either the simple calcs OR the FEA per se.

Remember "GIGO" introduced to be a cautionary comment on reliance on computers. FEA requires the same caution. If the assumptions/setting/context are wrongly defined FEA will produce either GO (garbage out) OR more dangerous, correct results for the wrong reasons. And that is the cautionary comment I made in reference to Enik's second attempt at FEA for the Col79-44 walk of issue. AND that is all I still am saying "it may be producing the right results for the wrong reasons - I have not studied it deeply enough to say...yet" Which, despite all the adverse commentary directed my way, is still a professionally sound interim position.

 

[ozeco41]

...That is much of the reason why a linear geometric approach cannot disprove a fire induced collapse.

I am stricken with abject jealousy.

It took you just 16 words to say what has taken me hundreds.

The key is "cannot disprove".

 

[ozeco41]

No it isn't that easy. Ozeco, and anyone who agrees with him, needs to provide the actual mechanisms for what he is claiming....

I am not making the claim under discussion. You are. All I have done is point out your logical error. Stop playing truther "reverse burden of proof" games. You may fool many members here. You do not and will not mislead me.

 

[Tony Szamboti]

I am not making the claim under discussion. You are. All I have done is point out your logical error. Stop playing truther "reverse burden of proof" games. You may fool many members here. You do not and will not mislead me.

I have already shown on this thread that column 79 could not have been pushed to the east any significant amount by its girders, since they would buckle before being able to do so. Column 44 was on the exterior and being cooled with a large moment frame keeping it in place.

The only possible movement between these two columns would have been from the girder between them expanding enough to generate a little more distance between them. In that case the girder would be locked between the flanges on column 44 and the build-up plates on column 79 and thus could not walk-off no matter how much the beams from the east pushed. In addition, this small amount of deflection of the columns by the girder would be in the elastic range and eliminated once the girder cooled.

Your supposition that there would be effects here that would affect the final outcome concerning the girder between the columns is not realistic and unsupported. You are just throwing stuff at the wall and demanding that it be given credence although you haven't shown it deserves it. That isn't the way things work. However, I will say emphatically that there are no effects which will cause a change in outcome. Now if you have a reply be prepared to support it logically.