Moderated WTC 1 features list, initiation model / WTC 2 features list, collapse model

[Major_Tom]

NIST NCSTAR 1.6 Executive Summary is an excellent condensed version of NISTian thought.

For our purposes, it serves as the perfect "CliffNotes" version of how the NIST attempted to show that impact damage and fires alone can explain the WTC1 collapse initiation.

This is the heart of what many posters here would call "proof" of how the impact and fires could reasonably result in the WTC 1 collapse.


The short summary linked again:
http://wtc.nist.gov/pubs/NCSTAR1-6ExecutiveSummary.pdf




Here is an outline of the summary:


E.1 PURPOSE AND SCOPE

To determine how and why the buildings collapsed following the initial impacts of the aircraft.


E.2 METHODOLOGY AND ANALYSIS RESULTS

E.2.1 Overview and approach: Specifies 11 steps of the NIST approach, listed as A. through K.

E.2.2 Structural response:

Passive fire protection for structural components

Test of truss floor components and subsystem

Structural response of components and detailed subsystems to assumed damage and fire:

Material properties and failure criteria
Floor subsystem analysis
Core column and exterior column and panel analysis


Aircraft impact damage

Observations and timeline of structural events:

WTC 1 key observations
WTC 2 key observations

Structural response of major tower subsystems:

Core subsystem
Full floor subsystem
Exterior wall subsystem

Structural response of the WTC towers:

WTC 1 global analysis results
WTC 2 global analysis results
Structural response of the WTC towers to fire without impact damage

Probable collapse sequence:

Possible collapse hypothesis (May 2003)
Working collapse hypothesis (June 2004)
Leading collapse hypothesis (October 2004)
Probable collapse sequence (May 2005)


E.3 PROBABLE COLLAPSE SEQUENCE OF WTC 1 AND WTC 2


E.4 FACTORS THAT AFFECTED PERFORMANCE


E.5 FINDINGS


E.5.1 Passive fire protection

E.5.2 Fire resistance tests

E.5.3 Structural response of components:

Floor system
Exterior wall system

E.5.4 Fireproofing and partition damage due to aircraft impacts

E.5.5 Observations and timeline:

WTC 1
WTC 2

E.5.6 Structural response of major tower subsystems:

Isolated core subsystem

Full floor subsystem

Isolated exterior wall subsystem

E.5.7 Structural response to aircraft impact damage and fire

E.5.8 Probable collapse sequence:

Role of building core

Role of the building floors

Role of exterior frame-tube

Probable collapse sequence

......................................
.....................................

This is a wonderful, easy-to-read version of the stated purpose of the NIST analysis, the NIST methodology and a condensed list of all major NIST findings. Using this outline, anyone can know in which section to look for a general answer of any basic question concerning the NIST version of WTC1 collapse initiation.

The title of this thread is "WTC1 feature list, initiation model". This executive summary acts as a good synopsis of a NIST version of a "WTC1 feature list" (or "list of observables") and the NIST initiation model.


It is fair to request that this is the minimum required reading to participate in this thread. There is no excuse for not knowing this material.

 

[carlitos]

The inability of the truthy people to be concise and succinct continues.

 

[ozeco41]

...The nature of our disagreement:

You claim that sufficient information exists within the NIST reports to support the claim that aircraft damage and fires led to collapse initiation independent of floor sagging and south wall failure. I claim that any explanation provided by the NIST relies on floor sagging and south wall failure.

Is this correct in your view? Is that the nature of our current disagreement?

No, it is not what I am saying. Recall this comment in my previous post:

......actually the issue I raise is independent of NIST. It is a matter of the structure of the claims and the logic relating the parts of claims....

The overall claim, again in my words, is "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse."

That is the "top level" scenario to which I subscribe along with a large body of professional and academic opinion including NIST.

That top level scenario does not depend on the structure of the NIST reports. In fact if we totally remove the NIST reports it still remains the broad based professional consensus as to why the Twin Towers collapsed. It stands in its own right based on the evidence. And at that top level the only other factor which has been suggested is "CD", "demolition", "MIHOP" - call it what you will for any form of human assistance to the collapse. And as we all know well there is no substantiated case for human assistance so that is a divergence at this point simply to get all the relevant issues on the table.

Therefore, whether or not NIST intended 'south perimeter led' to be the only possibility is a moot point. The structure of the issues is such that there could be alternative mechanisms to 'south perimeter led'.

So if we return to why we are discussing this, recall that Major_Tom made the following claim:

... were it to be shown that the NIST WTC1 initiation mechanism does not match the visual record, that would definitely shroud it's collapse in total mystery,..

I reckoned that he was claiming more than the logic or evidence supported so I responded with the following assertion:

...Major_Tom's claim, simply put, is that since one bit of detail of the NIST explanation is wrong THEREFORE the whole of the NIST explanation fails....

...and Major_Tom disagreed at some length. Nothing MT says changes the fact that the NIST overall position - aircraft plus fire damage = collapse - stands independent of NIST's 'south perimeter led' explanation. And it does so whether NIST wants it to or not.

And my advice to Major_Tom of "Don't claim more than your case can support" remains valid. Disproving 'south perimeter led' for WTC1 would not " definitely shroud it's collapse in total mystery," We would still know why WTC1 collapsed - it was the result of aircraft impact plus fire damage. Only the detailed mechanism would be affected, and we haven't seen that proved wrong at this stage.

 

[Dog Town]

And my advice to Major_Tom of "Don't claim more than your case can support" remains valid. Disproving 'south perimeter led' for WTC1 would not " definitely shroud it's collapse in total mystery," We would still know why WTC1 collapsed - it was the result of aircraft impact plus fire damage. Only the detailed mechanism would be affected, and we haven't seen that proved wrong at this stage.

Funny you should say this. Many "noise" makers have pointed this out, via question, at the very least. F2, and MT waved away, like drunks in a balcony! What an absolute waste of time!

 

[Major_Tom]

The overall claim, again in my words, is "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse."

A nice, concise summary.

I want to be very specific as to why I am following this line of reasoning.

This is what I am claiming:

1) The only analysis or "proof" behind this claim is in the NIST reports. Without the NIST summary, your claim is only a belief. There is no existing in depth analysis to back your claim outside of the NIST reports.

That is the "top level" scenario to which I subscribe along with a large body of professional and academic opinion including NIST.

WIthout analysis, this is only a shared beleif. It doesn't matter how many people hold this belief. There is no analytical proof outside of the NIST reports.

That top level scenario does not depend on the structure of the NIST reports. In fact if we totally remove the NIST reports it still remains the broad based professional consensus as to why the Twin Towers collapsed. It stands in its own right based on the evidence.

Without the NIST report, what evidence? You don't have any more.

Therefore, whether or not NIST intended 'south perimeter led' to be the only possibility is a moot point. The structure of the issues is such that there could be alternative mechanisms to 'south perimeter led'.

I agree that alternative mechanisms are possible,. ALso, other geometrical possibilities should be considered to explain inward bowing.

The problem is, that the NIST reports are your only analytical proof left. They may not be important to you, but without south perimeter failure through floor sagging, the whole NIST explanation for collapse falls to pieces.

It is not a moot point because you will be left with no more evidence, only a big "consensus" of shared belief.


To be clear, I am also making this claim:

2) Without south wall failure and sagging of OOS south flooring, the NIST explanation for "how and why" WTC1 collapsed has no more meaning. Their work and analysis for WTC1 is completely dependent on a specific failure mode: Considerable floor sagging which pulls in the south wall.

Nothing MT says changes the fact that the NIST overall position - aircraft plus fire damage = collapse - stands independent of NIST's 'south perimeter led' explanation. And it does so whether NIST wants it to or not.

The NIST position is totally dependent upon the scenario described in the NCSTAR 1-6 executive summary. If their only claim of evidence falls to pieces, how can they still claim that "aircraft plus fire damage = collapse"?

It is as if you are saying their overall position remains correct with or without any proof. According to you, even if their proof falls to pieces, their conclusions remain sound.

And my advice to Major_Tom of "Don't claim more than your case can support" remains valid. Disproving 'south perimeter led' for WTC1 would not " definitely shroud it's collapse in total mystery,"

Let me refine my claims to the two listed above. The "mystery" quote is only a consequence of the 2 claims above.

 

[ozeco41]

Funny you should say this. Many "noise" makers have pointed this out, via question, at the very least. F2, and MT waved away, like drunks in a balcony! What an absolute waste of time!

Yes. I hinted at it in my first post in the thread - Post #3.

This is more or less the common description of events:
1) Airplane strikes tower, does some damage, starts some fires.
2) Fires are not fought allowing more damage to accumulate.
3) The accumulating damage causes load shedding and load redistribution.
4) The load redistribution events build up into a cascading sequence which weakens the impact and damage zone.
5) The damage reaches the point where there is insufficient remaining strength to support the "top block".
6) The impact zone ceases to support the Top Block.
7) The Top Block starts to fall and from that instant "global collapse was inevitable"

So that is my description and, as far as I am aware, it aligns with NIST on the key points which matter.

Any more micro details may be of interest depending on the objective of the person expressing interest.

..I have since wondered if I was too subtle with the "details may be of interest" comment.
...and far too subtle with the "depending on the objective" follow up.

 

[GlennB]

" Major_Tom;6857465 ..... Does anyone have any proof that the south wall failed first, dragging the rest of the building down with it? ..... "


Yes.
Parallax correction over under sideways down graph ....
http://3.bp.blogspot.com/_uJ9AdKzfe...AYQ/s2-E3fyAfTQ/s1600/Pollock-Convergence.jpg

There is an unmatched right parenthesis ('flying smiley') in there that has been bugging me since yesterday. Which just became spooky.

 

[Major_Tom]

aircraft plus fire damage = collapse


Interesting equation. You imagine there is some kind of proof or reasonable analysis which equates the two.

My main point as clear as possible: There is none. Exactly as with the Bazant papers BV, BL and BLGB, any claim of proof disappears upon closer examination.


As I posted before,

My debate strategy is pretty clear. I have been following this general pattern:



a) First, Introduce a correct collapse propagation theory. Clear up many misunderstandings of all parties in the "debate". Misunderstandings by AE911T, by many regular JREF posters, by STJ911, by Bazant.

Knowledge and observation of the ROOSD process allow us to be specific when "debating" unlike any time previously.

Both self-proclaimed "debunkers" and "truthers" have helped spread many tall tales. The current atmosphere is thick with poor interpretation of photographic evidence. "The debate" is 95% hot air and fantasy. Knowledge of the ROOSD process destroys many of those illusions, allowing us to talk about specific features of collapse with a common underlying understanding for the first time.



b) Second, destroy the most common illusions that put a stranglehold on true, honest debate. For regular posters at JREF, this illusion is that some accepted authority has provided convincing answers to the demolition question.

The heart of this belief in such scientific authority is an attachment to the claims of "proof" by Dr Bazant and the NIST. Many posters are convinced that mechanisms of collapse of all three towers have been identified.

This is totally untrue. The collapses of all three towers remain a total mystery, and no scientific authority has come close to solving or explaining the mystery.


This is a fact that many here will fight to deny: The true causes for the collapses of all 3 towers remains unknown. In reality, the NIST was not able to identify the causes of any of the collapses.

No mechanism of collapse has yet been correctly identified


Speaking of illusions, to be fair, many claims by 9/11 truth groups are verifiably incorrect and these illusions must also be destroyed. The researchers that I feel have contributed most to 9/11 resreach have been largely ignored by the mainstream 9/11 truth movement. This is because many false claims have been made by AE911T, for example, and the researchers mentioned can probably call their bluff on those false claims. Unfortunately, the tendency of AE911T, for example, has been to shelter itself from honest debate with other truthers such as myself. Not healthy.



c) Once illusions have lost their power to dominate the scope of the "debate", and people overcome the tendency to cite abstract authority as decisive "proof", Free of the stranglehold of illusions, we will debate collapse features more clearly and specifically, maybe for the first time.


All features worth considering will be presented as comprehensive lists of information. We will find that a knowledge of the ROOSD process will give us a much better ability to see the collapse processes as a whole. We will also notice that many subtle features are seemingly inexplicable even with a knowledge of ROOSD.

From my experience, the more I have studied subtle features of the initiation processes and collapses, the more mysterious the events become.

There are many curious features that most people have not noticed about the actual events, mainly because they are looking for big bombs, or tons and tons of TNT, or space beams, or nukes......or pyroclastic clouds, or rivers and streams of molten metal....

If you know about the possibility of a ROOSD process, then you have a great advantage in knowing where to look for curious features of the collapses of WTC1 and 2. It's a great help. There are certain areas that cause natural discontinuities for the ROOSD process, like mechanical room floors, for example, that the observant researcher will want to study in detail.


In this thread I am working on part "b", destroying common illusions.

For regular posters at JREF, this illusion is that some accepted authority has provided convincing answers to the demolition question.

The heart of this belief in such scientific authority is an attachment to the claims of "proof" by Dr Bazant and the NIST.

In the case of the NIST, nobody seems to know where the "evidence" is, but they are quite convinced it is somewhere hidden within the reports.

This is your illusion. No such evidence exists.

Only a bunch of ....consensus.

 

[ozeco41]

The overall claim, again in my words, is "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse."

A nice, concise summary.

I have used it several times in recent posts.

...This is what I am claiming:...

Two overall comments before I address some of the points you raise:

1. First don't lose either context or perspective. We are involved in an Internet discussion. Recall that I have several times queried suggestions that your work is not valid unless submitted for peer reviewed publication. Obviously wrong on those many occasions when it is being used as an evasion by someone who is not prepared to attempt to rebut your claims. But also wrong in general, it is an Internet discussion, not an avenue of academic publishing. AND
2. Second you are confusing evidence with argument with authority with...whatever. See the following comment.

...1) The only analysis or "proof" behind this claim is in the NIST reports. Without the NIST summary, your claim is only a belief. There is no existing in depth analysis to back your claim outside of the NIST reports....

Nonsense. The evidence needed to support the conclusion "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse." is available on multiple you-tube videos if nothing else and what else is needed to support that overall summary?

The analysis which counts for this discussion is the analysis which you or I or other members do. NIST can provide a source for evidence or an indication as to where to look for primary evidence sources. NIST also provides analysis rationale but if you or I are putting forward an argument here it should be our argument - whether it closely follows NIST or diverges strongly. The very thing you are attempting here is a rebuttal of NIST work. You cannot consistently claim that the only analysis is that by NIST. And your claim "There is no existing in depth analysis to back your claim outside of the NIST reports" is simply untrue. Gravy, R Mackey here among others and my work on RDNet are examples of "in depth analysis" plus multiple academic papers which have been published. All provide access to evidence and examples of reasoning. But the reasoning which counts is what you and I and others put forward here. Sure there is a role for support from authorities but it is a secondary role.

From here your post degenerates to repetition of wrong claims:

...Without analysis, this is only a shared belief. It doesn't matter how many people hold this belief. There is no analytical proof outside of the NIST reports...

No analytical proof outside of NIST....wrong. In fact ludicrous. Remember context - this is an Internet discussion and the proof is the proof relevant to an Internet discussion. viz arguments and counter arguments supported by evidence.

...Without the NIST report, what evidence? You don't have any more....

NIST is the only source of evidence...

...I agree that alternative mechanisms are possible,. Also, other geometrical possibilities should be considered to explain inward bowing...

...no comment needed.

...The problem is, that the NIST reports are your only analytical proof left....

Wrong as already explained.

...They may not be important to you,..

Importance to me is not the criteria - in fact this is almost an ad-hom. What is important is the place that those arguments occupy in the structure of logic. And the 'south perimeter led' detailed explanation is only one possible explanation within the overall scope of "aircraft crash plus fire == collapse" situation.

...but without south perimeter failure through floor sagging, the whole NIST explanation for collapse falls to pieces...

Whether NIST falls apart on that detail is one of the points that I dispute. The other point I disagree with is your repeated confusion of objectives. your logic falters or fails when you swap objective from "explain WTC1 collapse initiation" to "prove NIST wrong".

...It is not a moot point because you will be left with no more evidence,..

Not so. the status of 'south perimeter led' detail has no effect whatsoever on availability of evidence. The evidence exists. It will not suddenly disappear if you show either 'south perimeter led' is false AND/OR 'core led' is right.

...only a big "consensus" of shared belief...

Well that is a strawman misinterpretation naturally - no other comment needed.

...To be clear, I am also making this claim:

2) Without south wall failure and sagging of OOS south flooring, the NIST explanation for "how and why" WTC1 collapsed has no more meaning. Their work and analysis for WTC1 is completely dependent on a specific failure mode: Considerable floor sagging which pulls in the south wall.

The NIST position is totally dependent upon the scenario described in the NCSTAR 1-6 executive summary. If their only claim of evidence falls to pieces, how can they still claim that "aircraft plus fire damage = collapse"?

It is as if you are saying their overall position remains correct with or without any proof. According to you, even if their proof falls to pieces, their conclusions remain sound....

Major_Tom you appear to have difficulty processing matters which involve different levels of system. There is a distinct hierarchy of issues here. Explaining systems hierarchy is way beyond a reasonable diversion for this thread so I will not attempt to do so.

The last quoted four paragraphs simply repeat the errors I have described earlier.

 

[Major_Tom]

Ozeco post 929: "Nonsense. The evidence needed to support the conclusion "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse." is available on multiple you-tube videos if nothing else and what else is needed to support that overall summary? "

Evidence? in the equation "aircraft plus fire damage = collapse" you are jumping over the collapse initiation scenario.

You have no collapse initiation mechanism besides the one offered by the NIST.

Nobody proved that equation. The equal sign is just belief. Let us go over the evidence you speak of.

Please list some evidence.

 

[Reactor drone]

aircraft plus fire damage = collapse


For regular posters at JREF, this illusion is that some accepted authority has provided convincing answers to the demolition question.

The heart of this belief in such scientific authority is an attachment to the claims of "proof" by Dr Bazant and the NIST.

In the case of the NIST, nobody seems to know where the "evidence" is, but they are quite convinced it is somewhere hidden within the reports.

Which demolition question is that? As far as I'm aware no one has ever presented any evidence supporting demolitions taking place in NY on september the 11th ,2001.

Bazant and NIST, through analysis, modelling and simulation show plausible mechanisms for collapse given the known events of that day i.e- aircraft impacts and fires. There is no need to analyse hypothetical demolitions for which no evidence exists.

The evidence isn't hidden within the NIST reports, the NIST reports are the write ups of the evidence. Analysis of physical samples, fire models, structural models and analysis of the visual record all indicate collapse due to damage from impact and fire. Since you have given links to it I'll assume you are familiar with the Ansys model in NCSTAR 1-6D and the associated column loading diagrams over time for both towers, if you need more detail about what was failing and when it was failing I'd suggest you look there.

 

[ozeco41]

Ozeco post 929: "Nonsense. The evidence needed to support the conclusion "aircraft impact damage and accumulating damage from unfought fires led to a cascade failure which initiated collapse followed by a global collapse." is available on multiple you-tube videos if nothing else and what else is needed to support that overall summary? "..

Please read my previous comment "Major_Tom you appear to have difficulty processing matters which involve different levels of system." It is the clue to the problem you face with understanding what I keep repeating.

...Evidence? in the equation "aircraft plus fire damage = collapse" you are jumping over the collapse initiation scenario...

We don't need it at the overall level. We know that the collapse initiated. The collapse followed the initiation. You want to suggest a different detail. But when and if you do it will not change the overall situation. The collapse started. That is all that we need to know at the overall level.

...You have no collapse initiation mechanism besides the one offered by the NIST...

This will become monotonous - we don't need to know what the initiation mechanism was if our interest is the overall situation where "aircraft impact plus fire damage led to collapse".

...Let us go over the evidence you speak of.

Please list some evidence.

No need if you comprehend what I am saying.

 

[Major_Tom]

I just needed to make thing clear. If you do not need any evidence or initiation mechanism, that is fine. Your position is unique, since many others seem to feel that the NIST report gives some kind of evidence which you do not seem to require.


That is your final statement, that there is no need to show any initiation mechanism or proof that fires and damage were in the range which could trigger collapse initiation?

I ask you for some evidence, and you say there is no need. We see the buildings get hit by airplanes, we see fires and we see the buildings fall.

That is enough, and there is no need for further evidence? As you say, "The collapse started. That is all that we need to know at the overall level."

But then you use the word "evidence" yourself. You simply mean that we can see the buildings fall using youtube video. That is what you mean when you use the word "evidence"?

I am just clarifying your position.

>>>>>>>>>>>>>>>>>>>

One other thing. The NIST states the purpose and scope of their reports as:

E.1 PURPOSE AND SCOPE

To determine how and why the buildings collapsed following the initial impacts of the aircraft.

Do you believe the NIST was successful in explaining the "how and why"? I know that from your point of view it is unimportant since youtube video provides sufficient evidence that the buildings did indeed fall. But just for the record, is the "how and why" of the WTC1 collapse explained correctly in the NIST reports?

If not, then it seems you would agree that the initiation mechanism of WTC1 remains a mystery despite the NIST claims of floor sagging leading to perimeter pull-in.. An unimportant mystery to you, yet unknown all the same?

I do not want to pester you. I only want to clarify your position.

It seems you would answer: "The "how and why" are unimportant details. The collapse started. That is all that we need to know at the overall level."

And lastly, this logic would apply to all 3 buildings. For WTC7 you would also seem to conclude that the "how and why" of initiation are unimportant details. The collapse started. That is all that we need to know at the overall level.

These are your exact words from post 932: "We don't need it at the overall level. We know that the collapse initiated. The collapse followed the initiation. You want to suggest a different detail. But when and if you do it will not change the overall situation. The collapse started. That is all that we need to know at the overall level."

Of course this means: "We do not need a collapse initiation scenario at the overall level. We know that the collapse initiated. The collapse started. That is all that we need to know at the overall level."

No need to re-type if this statement expresses your thoughts.

 

[Major_Tom]

I think we are almost ready to move on to discussing all the specific features of collapse initiation and progression (finally).


The list in the OP can be divided in the most general sense into 3 phases:

Pre-initiation
Collapse initiation
Collapse progression

The list is divided as...


Pre-initiation

Ejection from 75th Fl, E Side During AA11 Impact
Damage to Basement and Lobby
Fire, Smoke Ejections as WTC2 is Struck
Strong Fire Ejections As WTC2 Collapses
Inward Bowing of the S Perimeter
Ejections Witnessed at 10:18



Collapse initiation

Roofline Smoke Pulses just before Collapse
Fire Flair-up along E Face 3s before Collapse
Drift and Drop Movements Traced and Plotted: Summary
Upper West Wall Pulls Inward 9.5s before Collapse
Antenna Base Shifts Eastward 9.5s before Collapse
Antenna Sags 2 ft into Roofline before Falling
Roof Deforms Concavely before Falling
Earliest Ejections are from fl 95, W Face, S Side
Over-pressurization of fl 98 before Falling Begins
Tilt: Upper Portions tilt less than 1 Degree in 0.5s before Falling
West Face: All 60+ Columns W Fail Within 0.5s and 1 Degree
Adjacent Perimeter N and W Walls Fail Within 0.5s Interval
W Wall: Upper Breaks Outward as Large, Unbuckled Pieces
W Wall: Large Piece w/ Straight Break Along Bottom
NW Corner: Upper Slides Over N face and Behind W face
NW Corner: Lower Remains Standing Below Fl 98
NE Corner: Assembly has Straight Break along Bottom
N Wall: Upper Breaks Outward as Large, Unbuckled Pieces
E Wall: Breaks Outward as Large, Unbuckled Pieces
Jolts Detected in Earliest Antenna, NW Corner Drops
Acceleration: Early Downward Rates
88th Fl S Face Light Grey Ejection
77th Fl Over-pressurization Timing Inexplicable



Collapse progression

N and W Rooflines Lose Shape and Pull Inwards
Lower W Wall Pushed Outward Intact
Free-fall Comparison: Tracking Earliest Falling Object
Ejections Advancing Down NW and SW corners
Ejections Below Collapse Fronts
Mechanical Floor Ejections
Diagonal Ejections Traversing E Face, Fls 50-55
Lower Perimeter Peels Outward after Flooring Destroyed
Antenna Section Falls Southward
Entire E-W Width of the Core Survives Initial Collapse
Surviving Core Remnant Drops Collectively
Rubble Layout and Column Conditions Recorded



I'll move the progression features over to the "OOS progression model" thread.

The initiation and pre-initiation features will remain in this thread and will be used to construct an initiation model.

 

[alienentity]

The NIST describes how they conclude a collapse initiation sequence by using computer simulation models.



To me, from the executive summary it seems obvious that this "proof" depends on a particular failure mode, namely sagging floors resulting in IB to the point of south wall failure.

First, they have quantified the process in engineering terms, using very well established methods, it seems to me.
Second, the causes and consequences of the IB are well described and I think from that it is reasonably evident why the towers collapsed.

Nothing you've written or proposed is an adequate alternative to their work, IMO. I'm not saying your ideas are all without merit, but you are skipping most of the groundwork which would be necessary to match the NIST's.

Personally I think this is way beyond what you're capable of doing, but that's just my opinion.

 

[alienentity]

I think we are almost ready to move on to discussing all the specific features of collapse initiation and progression (finally).


The list in the OP can be divided in the most general sense into 3 phases:

Pre-initiation
Collapse initiation
Collapse progression

The list is divided as...



Collapse initiation

Roofline Smoke Pulses just before Collapse
Fire Flair-up along E Face 3s before Collapse
Drift and Drop Movements Traced and Plotted: Summary
Upper West Wall Pulls Inward 9.5s before Collapse
Antenna Base Shifts Eastward 9.5s before Collapse
Antenna Sags 2 ft into Roofline before Falling
Roof Deforms Concavely before Falling
Earliest Ejections are from fl 95, W Face, S Side
Over-pressurization of fl 98 before Falling Begins
Tilt: Upper Portions tilt less than 1 Degree in 0.5s before Falling
West Face: All 60+ Columns W Fail Within 0.5s and 1 Degree
Adjacent Perimeter N and W Walls Fail Within 0.5s Interval
W Wall: Upper Breaks Outward as Large, Unbuckled Pieces
W Wall: Large Piece w/ Straight Break Along Bottom
NW Corner: Upper Slides Over N face and Behind W face
NW Corner: Lower Remains Standing Below Fl 98
NE Corner: Assembly has Straight Break along Bottom
N Wall: Upper Breaks Outward as Large, Unbuckled Pieces
E Wall: Breaks Outward as Large, Unbuckled Pieces
Jolts Detected in Earliest Antenna, NW Corner Drops
Acceleration: Early Downward Rates
88th Fl S Face Light Grey Ejection
77th Fl Over-pressurization Timing Inexplicable

I take it this list is your own set of ideas.

It does concern me somewhat that a quick sampling of some of your points shows me that you are relying only on a certain visual interpretation of the events; and that your interpretation seems to be seriously mistaken even in the small sample I took.

For example, the gif under the 'Antenna Sags 2 ft into Roofline before Falling' heading shows a movement which is clearly far more than 2 ft, but worse, what you propose is not really possible (from what I understand of the hat truss structure) and the visual effect you're pointing to seems to be an unfortunate optical illusion due to the angle from which the video is taken.

A quick illustration of the problem can be given by viewing video such as this one, which shows the direction of the tilt and how the optical illusion came about.


I really don't think you have anything here. I did go to the website '9-11 Historic Archive' and I must say that, while it appears to be well organized, the tone of it is very unprofessional; starting with the fact that the 'author' is anonymous and including such gratuitous statements as 'There is overwhelming physical evidence that the official version of events is a fairy tale'

Oh well, I guess I shouldn't have expected much. I shudder to think that achimspok's work is listed as a 'best research video', having dealt with him on this forum.

 

[ozeco41]

I just needed to make thing clear. If you do not need any evidence or initiation mechanism, that is fine. Your position is unique, since many others seem to feel that the NIST report gives some kind of evidence which you do not seem to require....

Near enough for now - we have pursued the matter as far as I think is reasonable without derailing the thread.

...Of course this means: "We do not need a collapse initiation scenario at the overall level. We know that the collapse initiated. The collapse started. That is all that we need to know at the overall level."

No need to re-type if this statement expresses your thoughts.

Yes

I think we are almost ready to move on to discussing all the specific features of collapse initiation and progression (finally).

A good idea.

 

[BasqueArch]

NIST NCSTAR 1.6 Executive Summary is an excellent condensed version of NISTian thought.

For our purposes, it serves as the perfect "CliffNotes" version of how the NIST attempted to show that impact damage and fires alone can explain the WTC1 collapse initiation.

This is the heart of what many posters here would call "proof" of how the impact and fires could reasonably result in the WTC 1 collapse.


The short summary linked again:
http://wtc.nist.gov/pubs/NCSTAR1-6ExecutiveSummary.pdf




Here is an outline of the summary:


E.1 PURPOSE AND SCOPE

To determine how and why the buildings collapsed following the initial impacts of the aircraft.


E.2 METHODOLOGY AND ANALYSIS RESULTS

E.2.1 Overview and approach: Specifies 11 steps of the NIST approach, listed as A. through K.

E.2.2 Structural response:

Passive fire protection for structural components

Test of truss floor components and subsystem

Structural response of components and detailed subsystems to assumed damage and fire:

Material properties and failure criteria
Floor subsystem analysis
Core column and exterior column and panel analysis


Aircraft impact damage

Observations and timeline of structural events:

WTC 1 key observations
WTC 2 key observations

Structural response of major tower subsystems:

Core subsystem
Full floor subsystem
Exterior wall subsystem

Structural response of the WTC towers:

WTC 1 global analysis results
WTC 2 global analysis results
Structural response of the WTC towers to fire without impact damage

Probable collapse sequence:

Possible collapse hypothesis (May 2003)
Working collapse hypothesis (June 2004)
Leading collapse hypothesis (October 2004)
Probable collapse sequence (May 2005)


E.3 PROBABLE COLLAPSE SEQUENCE OF WTC 1 AND WTC 2


E.4 FACTORS THAT AFFECTED PERFORMANCE


E.5 FINDINGS


E.5.1 Passive fire protection

E.5.2 Fire resistance tests

E.5.3 Structural response of components:

Floor system
Exterior wall system

E.5.4 Fireproofing and partition damage due to aircraft impacts

E.5.5 Observations and timeline:

WTC 1
WTC 2

E.5.6 Structural response of major tower subsystems:

Isolated core subsystem

Full floor subsystem

Isolated exterior wall subsystem

E.5.7 Structural response to aircraft impact damage and fire

E.5.8 Probable collapse sequence:

Role of building core

Role of the building floors

Role of exterior frame-tube

Probable collapse sequence

......................................
.....................................

This is a wonderful, easy-to-read version of the stated purpose of the NIST analysis, the NIST methodology and a condensed list of all major NIST findings. Using this outline, anyone can know in which section to look for a general answer of any basic question concerning the NIST version of WTC1 collapse initiation.

The title of this thread is "WTC1 feature list, initiation model". This executive summary acts as a good synopsis of a NIST version of a "WTC1 feature list" (or "list of observables") and the NIST initiation model.


It is fair to request that this is the minimum required reading to participate in this thread. There is no excuse for not knowing this material.

​

 

[raff55]

Just trying to encapsulate,

Major Tom
If what you are postulating on this thread is correct. What in your opnion does this lead you to consider ?

 

[Major_Tom]

Tilt angles revisited.

There is a new tool that we can use to determine accurate tilt angles over which all the columns originally failed.

The linked video synchronized the Sauret clip with the Ballou clip from the northeast:
http://www.youtube.com/user/femr2?&MMN_position=312:312#p/u/3/_lnHn9yN6Is

A person only has to find the moment when the window washer unit on the NW corner begins to move downward. A conservative guess puts that moment at the 0:32 mark in the linked video. This is the moment the NW corner starts to visibly move downward:

As anyone can see, ther is almost no tilt angle at this moment.


TFK posted the image below as his proof that the building tilted at least 4 degrees over initial failure sequence:

This is an over-exaggeration of the angle over which the building tilted as the columns failed from south to north. Most every posted measurment in this thread makes the same mistake of exaggerating the tilt angle of the initiation sequence.

The NIST also over-exaggerates the original tilt angle over which the columns failed. It is easy to see how this mistake leads to the belief that the south wall must have initiated collapse.

A magnified tilt estimate will lead to the mistaken impression that the building must have failed along the south wall. If you look at the real angles of tilting at the moment the NW corner starts to move downwards as a falling unit, as shown the first image above, it is not clear whether the south wall or the core actually failed first.