ergo
Illuminator
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Moderated WTC 1 features list, initiation model / WTC 2 features list, collapse model
Discussion on global collapse split to new thread.
Posted By: Gaspode
The consistent theme in the ozeco41, R Mackey and DGM posts is that if the core dropped out of WTC1 initiating collapse, that is just a detail and does not affect the NIST's sound conclusions.
Ozeco post 41: "Whether it was "perimeter led" or "core led" does not change the overall picture that a weakened impact zone dropped the top block and from that point "global collapse was inevitable."
DGM post 43: "How does any of this invalidate the NIST findings? I would expect movement caused by redistribution of load. Would any of this be inconsistent of this?"
R Mackey post 56: "Nailed it. "NIST got a detail wrong" != "Inside Job.""
Grizzly Bear post 60: "The detail nitpicking of the NIST report however is IMO grasping at straws"
This represents the most common reaction to the features list.
Multiple observations indicate core movement beginning about 9.5 seconds before visible initiation, pulling the west wall inwards. Early core sagging into the roof line is visible to anyone who looks carefully in the moments just before collapse, while the SW corner has not yet moved downward.
My first question is: Are the posters aware of the early antenna and west wall movements? Do you acknowledge the features exist as described? (It is hard for me to understand why the obvious contradictions between the NIST's description of south wall failure and the list of observations in the OP are seen as insignificant details.)
Second question: Are the posters even aware that the NIST's conclusions are based on a particular collapse mode (south perimeter failure due to floor sagging) and the conclusions and models presented have no meaning for a core-led collapse initiation sequence?
Ozeco post 41: "Whether it was "perimeter led" or "core led" does not change the overall picture that a weakened impact zone dropped the top block and from that point "global collapse was inevitable."
DGM post 43: "How does any of this invalidate the NIST findings? I would expect movement caused by redistribution of load. Would any of this be inconsistent of this?"
R Mackey post 56: "Nailed it. "NIST got a detail wrong" != "Inside Job.""
Grizzly Bear post 60: "The detail nitpicking of the NIST report however is IMO grasping at straws"
This represents the most common reaction to the features list.
Multiple observations indicate core movement beginning about 9.5 seconds before visible initiation, pulling the west wall inwards. Early core sagging into the roof line is visible to anyone who looks carefully in the moments just before collapse, while the SW corner has not yet moved downward.
My first question is: Are the posters aware of the early antenna and west wall movements? Do you acknowledge the features exist as described? (It is hard for me to understand why the obvious contradictions between the NIST's description of south wall failure and the list of observations in the OP are seen as insignificant details.)
Second question: Are the posters even aware that the NIST's conclusions are based on a particular collapse mode (south perimeter failure due to floor sagging) and the conclusions and models presented have no meaning for a core-led collapse initiation sequence?
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For example consider these two observations:
Upper West Wall Pulls Inward 9.5s before Collapse
Antenna Base Shifts Eastward 9.5s before Collapse
Just before collapse it is important to trace the movement carefully because the earliest failures that lead to movement could be detectable.
The NIST described the upper section as tilting as a "rigid block". It did not and the early deformation from rigidity is clearly connected to what areas in the tower yielded first.
It would be foolish to ignore the earliest detectable movements.
Upper West Wall Pulls Inward 9.5s before Collapse
Antenna Base Shifts Eastward 9.5s before Collapse
Just before collapse it is important to trace the movement carefully because the earliest failures that lead to movement could be detectable.
The NIST described the upper section as tilting as a "rigid block". It did not and the early deformation from rigidity is clearly connected to what areas in the tower yielded first.
It would be foolish to ignore the earliest detectable movements.
You make a big issue of a movement observed 9.5s before collapse, but the fact remains that the inward movement of portions of the wall creating the "bowing" happened many minutes before that. And before that, multiple portions of the structure moved in multiple different ways when the plane hit the building.
I recall someone arguing that the bowing doesn't count as movement based on some definition of significant movement requiring that it be sustained or lead immediately and rapidly to further movement, but with those restrictions the movement 9.5s before collapse doesn't count either.
Which is silly either way; it all counts, it's all movement, and as firefighters say, a moving building is a collapsing building. Maybe some core columns did give way and unload 9.5s before the rapid collapse. We know that many of them were already damaged to varying degrees and we know that the thermal effects and the bowing of the wall was putting increased stress on them. The models show that it's overwhelmingly likely that some were sufficiently damaged to no longer support any load when the planes crashed, while others were partially damaged. So does that automatically make it a "core led" collapse? If not, why does one or a few more core columns (perhaps some of the partially damaged ones) giving way and reaching (for about another 9s) a new equilibrium with further redistributed loads make it "core led"?
Part of any such redistribution of load would be to put more stress on the bowing columns. If that happened, what happened next? Further bending and unloading of the wall, causing more core columns to break? The beginning of buckling of the wall, transferring additional stress to the core causing more core columns to break? Or a direct transition to further core column failure, inevitably causing further deformation of the already bowed wall in the process? Without strict definitions of the starting and ending moments of such overlapping and time-extended events as "core failure," "wall failure", "wall bowing," "wall buckling", "movement," and "collapse," -- which femr2 has made clear will not be forthcoming -- these questions and the distinctions they imply are inherently vague, if coherent at all.
Everything was moving. Everything started moving the moment the plane hit, and everything continued moving until it all came to rest on the ground. Some of those movements were large enough and/or fast enough to be visually observed and measured, and some were not. Some of them were fast enough and large enough to be felt and heard as creaks and thumps prior to collapse, and some were not. No part of the building was ever completely rigid, from the start, because nothing is completely rigid especially at that size.
So what's the issue? "Core led?" As best we can tell, the plane destroyed some of the core columns (as well as perimeter columns on two sides) first so wouldn't "airplane led" be more appropriate? If for some reason you only want to talk about large movements subsequent to the collisions and prior to the rapid collapse and causing visible distortion in the "rigid" structure, then the wall bowing is the largest and earliest movement observed. If for some reason you only want to talk about large movements subsequent to the collisions and prior to the rapid collapse and causing visible distortion in the "rigid" structure and that also happened in a short rapid time frame, how is that not just cherry picking? If some core columns (perhaps already heavily damaged) moved or failed after the plane crash and before the rapid collapse phase, exactly as might be expected under conditions in which a load-bearing outer wall was already in the process of moving and failing, so what?
NIST's narrative of "what happened in what order," like any historical narrative on any time scale, is necessarily a simplification and an approximation of a complex process in which many parts of an interconnected system are acting and being acted upon at once. The wall failure was directly observable while the core failure was not, so perhaps the role of the former was exaggerated and you can offer a different (but equally simplified and approximated) narrative.
Or perhaps not; you have not proved "core led" because the movement 9.5s before the rapid collapse clearly does not represent failure of the entire core (since complete collapse did not immediately follow). If which part experiences partial failure first is what matters then as I said the collapse was "airplane led." "Core led" would have to mean complete core failure before complete wall failure, or something like that, which you have not shown, and which might not be consistent with the way the rotation of the upper block progressed. The center dip and inward compression 9.5s before collapse did not continue, nor noticeably resume later. The rotation beginning 9.5s later kept going into complete collapse. That strongly suggests to me that at that point, whatever might have gone before, wall failure proceeded to completion ahead of core failure.
I appreciate knowing the additional details, and as I said a long time ago I applaud femr2's efforts in finding them out. But I don't see these particular details as having much effect on the historical narrative. Knowing that Dawes not Revere brought warning to Lexington in 1775, and that the warning wasn't fully heeded (a few hours later many of the militia apparently believed it had been a false alarm, as the actual British approach to the town became a last-minute surprise) doesn't mean it's plausible that maybe the Lexington minutemen really shot themselves on Lexington Green.
Why should those who, unlike me, do not care about historical details for their own sake, care about the movements you're arguing for, 9.5s before the main collapse? What do they change? What do they mean?
Respectfully,
Myriad
I recall someone arguing that the bowing doesn't count as movement based on some definition of significant movement requiring that it be sustained or lead immediately and rapidly to further movement, but with those restrictions the movement 9.5s before collapse doesn't count either.
Which is silly either way; it all counts, it's all movement, and as firefighters say, a moving building is a collapsing building. Maybe some core columns did give way and unload 9.5s before the rapid collapse. We know that many of them were already damaged to varying degrees and we know that the thermal effects and the bowing of the wall was putting increased stress on them. The models show that it's overwhelmingly likely that some were sufficiently damaged to no longer support any load when the planes crashed, while others were partially damaged. So does that automatically make it a "core led" collapse? If not, why does one or a few more core columns (perhaps some of the partially damaged ones) giving way and reaching (for about another 9s) a new equilibrium with further redistributed loads make it "core led"?
Part of any such redistribution of load would be to put more stress on the bowing columns. If that happened, what happened next? Further bending and unloading of the wall, causing more core columns to break? The beginning of buckling of the wall, transferring additional stress to the core causing more core columns to break? Or a direct transition to further core column failure, inevitably causing further deformation of the already bowed wall in the process? Without strict definitions of the starting and ending moments of such overlapping and time-extended events as "core failure," "wall failure", "wall bowing," "wall buckling", "movement," and "collapse," -- which femr2 has made clear will not be forthcoming -- these questions and the distinctions they imply are inherently vague, if coherent at all.
Everything was moving. Everything started moving the moment the plane hit, and everything continued moving until it all came to rest on the ground. Some of those movements were large enough and/or fast enough to be visually observed and measured, and some were not. Some of them were fast enough and large enough to be felt and heard as creaks and thumps prior to collapse, and some were not. No part of the building was ever completely rigid, from the start, because nothing is completely rigid especially at that size.
So what's the issue? "Core led?" As best we can tell, the plane destroyed some of the core columns (as well as perimeter columns on two sides) first so wouldn't "airplane led" be more appropriate? If for some reason you only want to talk about large movements subsequent to the collisions and prior to the rapid collapse and causing visible distortion in the "rigid" structure, then the wall bowing is the largest and earliest movement observed. If for some reason you only want to talk about large movements subsequent to the collisions and prior to the rapid collapse and causing visible distortion in the "rigid" structure and that also happened in a short rapid time frame, how is that not just cherry picking? If some core columns (perhaps already heavily damaged) moved or failed after the plane crash and before the rapid collapse phase, exactly as might be expected under conditions in which a load-bearing outer wall was already in the process of moving and failing, so what?
NIST's narrative of "what happened in what order," like any historical narrative on any time scale, is necessarily a simplification and an approximation of a complex process in which many parts of an interconnected system are acting and being acted upon at once. The wall failure was directly observable while the core failure was not, so perhaps the role of the former was exaggerated and you can offer a different (but equally simplified and approximated) narrative.
Or perhaps not; you have not proved "core led" because the movement 9.5s before the rapid collapse clearly does not represent failure of the entire core (since complete collapse did not immediately follow). If which part experiences partial failure first is what matters then as I said the collapse was "airplane led." "Core led" would have to mean complete core failure before complete wall failure, or something like that, which you have not shown, and which might not be consistent with the way the rotation of the upper block progressed. The center dip and inward compression 9.5s before collapse did not continue, nor noticeably resume later. The rotation beginning 9.5s later kept going into complete collapse. That strongly suggests to me that at that point, whatever might have gone before, wall failure proceeded to completion ahead of core failure.
I appreciate knowing the additional details, and as I said a long time ago I applaud femr2's efforts in finding them out. But I don't see these particular details as having much effect on the historical narrative. Knowing that Dawes not Revere brought warning to Lexington in 1775, and that the warning wasn't fully heeded (a few hours later many of the militia apparently believed it had been a false alarm, as the actual British approach to the town became a last-minute surprise) doesn't mean it's plausible that maybe the Lexington minutemen really shot themselves on Lexington Green.
Why should those who, unlike me, do not care about historical details for their own sake, care about the movements you're arguing for, 9.5s before the main collapse? What do they change? What do they mean?
Respectfully,
Myriad
Hokulele
Deleterious Slab of Damnation
With the hat truss in place, I would think it would be difficult to determine whether it was the transfer of the load from the failing perimeter that caused the core to fail first (if in fact it did fail first), or if it was something wrong with the core columns themselves.
I'm not a follower of these threads, but I found your post
It seems to boil down to cherry picking anomalies and then setting up a false dichotomy.
As an engineer it was the false dichotomy that set off alarm bells for me. Unlike grade school, life is never limited to two choices.
Thanks for taking the time to once again put to words what must be a very boring post for you. Even after all of these years, the peanut gallery does appreciate it.
The NIST initiatlon scenario in their own words:
1-6draft p 290, figure 9-8 on probable collapse initiation sequence for WTC1:
Quote:
Collapse Initiation
• The inward bowing of the south wall induced column instability, which progressed rapidly horizontally across the entire south face.
• The south wall unloaded and tried to redistribute the loads via the hat truss to the thermally weakened core and via the spandrels to the adjacent east and west walls.
• The entire section of the building above the impact zone began tilting as a rigid block (all four faces; not only the bowed and buckled south face) to the south (at least about 8º) as column instability progressed rapidly from the south wall along the adjacent east and west walls.
• The change in potential energy due to downward movement of building mass above the buckled columns exceeded the strain energy that could be absorbed by the structure. Global collapse then ensued.
There are multiple features which show the initiation was from the core, the first pull-down movement was through the core, not the south perimeter wall.
Can you name any physical features of movement during collapse initiation which supports the NIST scenario?
It is as if they are describing a different building than the one we see studied in the list of features.
1-6draft p 290, figure 9-8 on probable collapse initiation sequence for WTC1:
Quote:
Collapse Initiation
• The inward bowing of the south wall induced column instability, which progressed rapidly horizontally across the entire south face.
• The south wall unloaded and tried to redistribute the loads via the hat truss to the thermally weakened core and via the spandrels to the adjacent east and west walls.
• The entire section of the building above the impact zone began tilting as a rigid block (all four faces; not only the bowed and buckled south face) to the south (at least about 8º) as column instability progressed rapidly from the south wall along the adjacent east and west walls.
• The change in potential energy due to downward movement of building mass above the buckled columns exceeded the strain energy that could be absorbed by the structure. Global collapse then ensued.
There are multiple features which show the initiation was from the core, the first pull-down movement was through the core, not the south perimeter wall.
Can you name any physical features of movement during collapse initiation which supports the NIST scenario?
It is as if they are describing a different building than the one we see studied in the list of features.
bill smith
Philosopher
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'' Maybe some core columns did give way and unload 9.5s before the rapid collapse. ''
Would you care to speculate further on that ?
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Reactor drone
Graduate Poster
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Major Tom, do you think the antenna movement you detected could be due to movement in the hat truss (which the antenna was attached to) as it redistributed the load from the south wall?
Again, it would be helpful to your case if you wrote up your results in a single paper along the lines of NCSTAR 1-5a with a timeline and relevant features pointed out with your movement traces and any engineering models or calculations you feel are relevant to demonstrate your points.
Again, it would be helpful to your case if you wrote up your results in a single paper along the lines of NCSTAR 1-5a with a timeline and relevant features pointed out with your movement traces and any engineering models or calculations you feel are relevant to demonstrate your points.
ozeco41
Philosopher
Correct as it relates to my position and in the context which I made explicit and which your quote loses. So let's resolve some ambiguities...
Major_Tom I am aware of your preferred discussion style or tactics. Here we see you lead off with ambiguous use of the phrase "...NIST's sound conclusions..." Ambiguous in that you use the phrase to suit your post and ignore the context in which I supported the NIST findings with the statement "I don't see how any of this invalidates the main thrust of the NIST findings." Note specifically the term "main thrust". I was clearly referring to the overall findings, the broad features or parameters beneath which there are levels of detail.
My statements in this thread led off with a "broad picture" of the several major stages of collapse. The relevant bits here being:
Note the comment "...aligns with NIST on the key points which matter." And those which matter depend on your objective in pursuing analysis. The only two valid objectives I am aware of relevant to this discussion being personal technical interest in the detailed mechanisms OR a desire to support a demolition hypothesis.
So you are pursuing details which, at this stage, fall within those stages 5, 6 and 7. I find your work interesting and am waiting for you to reveal more of it.
I have no interest in discussing it until and if it falls outside my own broad findings as to those stages 5, 6 and 7 AND my own finding that there was no demolition. Both of those criteria align with my understanding of the NIST position. Until then I have no interest in discussion. I covered that in my last sentence "Any more micro details may be of interest depending on the objective of the person expressing interest." You are interested in the details for some reason.
So there is no need for me to answer your two questions but I will so that my position is unambiguous:
Responding to 1 and 2 You are developing your statement. I will await your findings and your claims as to relevance. Specifically if they affect the two criteria I identified above i.e. change the collapse sequence OR introduce CD.
..and 3 Two points. (1) The possible picture of contradictions you are building is "insignificant details" in the context of my interst and I suspect the interest ofmany others posting here. AND (2) ...if the contradictions are to become significant it is your responsibility (burden of proof) to put forward and support a reasoned claim.
"ho hum!" ... or, more seriously, a question of little interest to me until you put it in a context and a claim which attracts my attention. The criteria as previously stated.
Now your post seems to imply that you disagree with my statement:
Setting aside innuendos, intended or not, do you disagree with that statement of mine?
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Sure, some of the core columns were known with near certainty to be damaged and known with absolute certainty to be under increasing stress and strain as a result of the fires and the already failing south wall. So it is no surprise that additional core columns might shift or break during this period, further redistributing the loads.
We also know that this movement 9.5s before collapse did not initiate the full collapse, and the rotational movement when full collapse did initiate was different from, not a continuation of, the inward movement possibly observed 9.5s earlier, suggesting that ultimately, south wall failure proceeded ahead of core failure.
Oh, wait, I already said all that, in the part of my previous post that you didn't quote in bold. But they're important points anyhow, worth repeating.
Respectfully,
Myriad
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JackDaniels
Scholar
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I tried that on my mac, but Preview simply won't display it. I am using an old system (10.4.11); maybe that's the problem.
Myriad post 73: "We also know that this movement 9.5s before collapse did not initiate the full collapse, and the rotational movement when full collapse did initiate was different from, not a continuation of, the inward movement possibly observed 9.5s earlier, suggesting that ultimately, south wall failure proceeded ahead of core failure."
You just made that up. Where do you dream up this information?
You just made that up. Where do you dream up this information?
bill smith
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How many seconds before collapse were the fireballs observed ?
Ozeco, if you are not interested in the details of WTC1 collapse initiation, perhaps this thread is not for you.
Ozeco post 72: "I have no interest in discussing it until and if it falls outside my own broad findings as to those stages 5, 6 and 7 AND my own finding that there was no demolition."
Then don't. That's fine. I cannot think in that little box you built around the study of collapse initiation. I'll stick to the title of the thread and the OP. Participation is not mandatory.
I actually look at collape initiation instead of reasoning why I don't. According to your logic you don't have to look at anything that actually happened. The actual events are treated as unimportant details.
Ozeco: "The possible picture of contradictions you are building is "insignificant details" in the context of my interst and I suspect the interest ofmany others posting here."
I don't care. I am describing collapse initiation and other features as they really happened. The NIST report describes a fairy tale event that contradicts the visual record. Many people need fairy tales. I prefer to study the events themselves.
Nobody seems to have a problem with the NIST feeding you a fantasy collapse initiation scenario and building their report around it, yet a list of actual recorded features is frowned upon as "insignificant". To me that is pure hypocrisy.
My guess is that many of the posters do not understand how the NIST reports rely on a perimeter collapse scenario, or that they haven't understood the information presented in the OP.
Either way, I will describe what is known about the initiation process and the events leading up to it in this thread.
Ozeco post 41: "Whether it was "perimeter led" or "core led" does not change the overall picture that a weakened impact zone dropped the top block and from that point "global collapse was inevitable."
Totally disagree. Where have you read any proof that the core was expected to fall out of WTC1?
NIST says a weakened south wall gave. The weakness in the design according to them were the long span trusses. Perimeter-led. You are saying impact damage, jet fuel and fires took out the core now? Any proof at all?
I also show the 98th floor had a strong overpressure before any measurable point on the perimeter or antenna was measured to fall downwards. For you another detail not worth seeing.
77th floor overpressure during collapse initiation 20 floors above. Another detail not worth seeing.
The NIST models and initiation scenario are built around the long trusses sagging and pulling in the perimeter. None of it applies to core-led collapse.
"Blocks" do not exist for WTC1. There is measurable deformation and failure as a deforming object. The deformation and earliest movement tells you what part of the building gave first.
It's called a "core", not a "block". Big difference.
Ozeco post 72: "I have no interest in discussing it until and if it falls outside my own broad findings as to those stages 5, 6 and 7 AND my own finding that there was no demolition."
Then don't. That's fine. I cannot think in that little box you built around the study of collapse initiation. I'll stick to the title of the thread and the OP. Participation is not mandatory.
I actually look at collape initiation instead of reasoning why I don't. According to your logic you don't have to look at anything that actually happened. The actual events are treated as unimportant details.
Ozeco: "The possible picture of contradictions you are building is "insignificant details" in the context of my interst and I suspect the interest ofmany others posting here."
I don't care. I am describing collapse initiation and other features as they really happened. The NIST report describes a fairy tale event that contradicts the visual record. Many people need fairy tales. I prefer to study the events themselves.
Nobody seems to have a problem with the NIST feeding you a fantasy collapse initiation scenario and building their report around it, yet a list of actual recorded features is frowned upon as "insignificant". To me that is pure hypocrisy.
My guess is that many of the posters do not understand how the NIST reports rely on a perimeter collapse scenario, or that they haven't understood the information presented in the OP.
Either way, I will describe what is known about the initiation process and the events leading up to it in this thread.
Ozeco post 41: "Whether it was "perimeter led" or "core led" does not change the overall picture that a weakened impact zone dropped the top block and from that point "global collapse was inevitable."
Totally disagree. Where have you read any proof that the core was expected to fall out of WTC1?
NIST says a weakened south wall gave. The weakness in the design according to them were the long span trusses. Perimeter-led. You are saying impact damage, jet fuel and fires took out the core now? Any proof at all?
I also show the 98th floor had a strong overpressure before any measurable point on the perimeter or antenna was measured to fall downwards. For you another detail not worth seeing.
77th floor overpressure during collapse initiation 20 floors above. Another detail not worth seeing.
The NIST models and initiation scenario are built around the long trusses sagging and pulling in the perimeter. None of it applies to core-led collapse.
"Blocks" do not exist for WTC1. There is measurable deformation and failure as a deforming object. The deformation and earliest movement tells you what part of the building gave first.
It's called a "core", not a "block". Big difference.
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ergo
Illuminator
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Earliest Detectable and Drop Movements Traced and Plotted
still not working. Perhaps someone could quote me, so Major Tom will see this.
still not working. Perhaps someone could quote me, so Major Tom will see this.
My assertion contained three statements. I'll gladly provide my rationale for stating each of them, and you can point out any flaws in my reasoning.
We know this because the building did not collapse 9.5 seconds earlier.
The movement of the upper block when collapse occurred had two predominant components: rotation around an axis near the north wall, and falling. The initial southward tilt is confirmed in many observations including your own. The initial rotation was also robust enough to impart sufficient angular momentum on the upper block to continue its rotation well after the release of all columns. If any further north-south inward pulling occurred, it was concurrent with, and small in magnitude in comparison to, the rotation. (East-west inward pulling is equally consistent with earlier core failure or earlier failure of the center of the south wall.)
That is a logical conclusion from the previous two observations (hence the word "suggesting"). The rotation that is observed necessarily involves greater displacement at the south wall than at the core. Greater displacement strongly suggests (though it does not prove) a more advanced state of failure.
Respectfully,
Myriad