Assuming you are correct, that A2001 had to fail in order for Building 7 to collapse, you have limited the possible failure to "walk-off" at column 79, and "extreme sagging", both of which you claim "impossible". Your premise is invalid due to limited choices. There is another end to A2001, the perimeter wall connection, which could have failed.
NIST does, in effect, say that with this quote. And they offer no other possibility.
Without the failure of A2001 on the 13th floor, column 79 would still have support in the east-west direction and it would not have buckled. The walk-off of A2001 is the crux of the NIST hypothesis. If it doesn't happen, the rest of the collapse doesn't happen. It doesn't happen in the video because it is impossible for thermal expansion to push the A2001 girder off of its seat. The video shows that it doesn't which disproves the NIST hypothesis. What it does show is a fraudulent depiction of A2001 sagging far more than it would at 400 °C. (or even 600 °C )
For the NIST hypothesis to be correct, A2001 had to be pushed off of its seat at column 79. If that doesn't happen, the NIST hypothesis is invalid.
"The star of the show" refutes the NIST hypothesis. Therefore, the NIST hypothesis is not valid.
I think you miss the point.
No, the point I am making is:
I don't believe that any of this happened so there is no justification for any of it. But justified or not, NIST did focus on A2001 to get their hypothesis to work. In the NIST hypothesis, the walk-off of A2001 is the trigger that started the total collapse. Without that triggering event, their collapse never starts. So it is definitely a 'key' factor in the NIST collapse scenario.
You keep going round and round in circles. Yes, we can safely say that if A2001 did not walk off, then any hypothesis that relies upon that walk-off is false.
Correct. If A2001 did not walk off, then the NIST hypothesis, which relies upon that walk-off, is false. You cannot claim that the NIST hypothesis is anything other than what they said it is.
NIST did not put the simulation in their final report, they released it at the same time they stated in their final report that the collapse was triggered by the walk-off of A2001.
That is not a puzzle. They stated clearly and unequivocally that the walk-off of A2001 was the trigger that started the collapse. And they went into great detail as to how the floor beams pushed the A2001 girder off of its seat.
Either the NIST narrative invalidates the simulation or the simulation invalidates the NIST walk-off hypothesis.
Hogwash! There was no other simulation. You are making stuff up to justify your denial that the NIST hypothesis is based on the A2001 girder walk-off.
AE911Truth has presented conclusive proof of controlled demolition. i.e. none of this happened.
It is what the NIST final report says. The video is not the NIST report. It accompanies the NIST report, The report is the 1000+ page written document.
Yes, the simulation shows the A2001 girder failing because it is sagging far more than it possibly could, That is fraudulent.
And therein lies the rub. Both cannot be true. Therefore, one is false. Take your pick but you can't have it both ways.
Of course. Everyone, including NIST, has it wrong, but you have it right.
No, it's in there. There are renderings taken from the non-walk-off simulation.
How did they figure it out without doing a new simulation?
You ignored my question about the other end of A2001; the perimeter wall connection. "Walk-off" at column 79 isn't the only possible scenario for A2001 to fail.
Specifically, figure 2-2
You are right. My bad.
watch yourself. this is paraphrasing. Mick said no such thing.
This again is paraphrasing. Mick has never denied NISTS "probable cause of collapse" includes the walk off.
This is a false dichotomy. I think the more likely explanation is what we discussed two years ago. They had two different sets of damage results that were both attributed to 4.0 hours of Case B temperatures. One of which is shown in the draft report (no walk-off) and one of which is shown in the final report (walk-off). The images were manually edited to include this data. Of course, they could not manually edit the multiple simulation videos.
my guess is they just didn't want to tweak it and run it again, because didn't it take like 8 months to render the one simulation we see? and does it really matter if the support was lost due to a walk off or just the beam sag?
I think they had a much more comprehensive set of runs from the initial simulation and had already written up the report based largely on that. But then they discovered the walk-off in a more limited investigation, and for some reason decided to use that. Rember their brief was to find why the building collapsed so they could learn from it and make future buildings safer. They discovered the significant effects of thermal expansions, and how it could lead to progressive collapse. So they led with that, even though it meant putting out a somewhat messy mixed report.
I see what you are saying and you are correct. My apologies.
that's what I said
or what I meant anyway.
I was responding to MIck's saying "Why they did this is a puzzle". I did answer 'why' they did this. It is perfectly clear why they 'did this'. It's their scenario.
That is what this thread is all about. Mick is saying that in their final analysis (the video simulation) the NIST hypothesis is one where the girder does not walk-off. He thought it was a puzzle why they "gave a narrative in which A2001 DID walk off" and said that statement was likely based on a different simulation that for some reason they did not have visualizations of.
That's a lot of supposition. But in the end, it's just a sugar coated way of saying that NIST lied about walk-off being the trigger that started the collapse.
How do you figure? I mean what's the actual logic steps that lead to this conclusion?
Which means the NIST triggered-by-walk-off hypothesis would be wrong - but collapse ensues regardless
Right - and collapse ensues
But collapse still ensued, with fire as root cause being the obvious null hypothesis
Hulsey's depictions show things that are physically impossible.
Sometimes? That's the only scenario they talk about. It doesn't show that in the simulation because it's impossible as I just pointed out in a post that you deleted because of speculation. I posted the 3 reasons why walk-off is impossible in post #102 which was not deleted. They are established facts, not speculation.
But they sometimes don't talk about it. For example in the Final Report (1A) right at the start, in the Executive Summary, they say:
Don't you think if they had found a more precise initiating event they would have included it in the executive summary? Instead the walk-off hypothesis is mentioned only once in section 2.4:
Eventually, the fires reached the northeast region of the building. The probable collapse sequence that
caused the global collapse of WTC 7 involved the initiation of the buckling of a critical interior column in
that vicinity. This column had become unsupported over nine stories after initial local fire-induced
damage led to a cascade of local floor failures. The buckling of this column led to a vertical progression
of floor failures up to the roof, and led to the buckling of adjacent interior columns to the south of the
critical column. An east-to-west horizontal progression of interior column buckling followed, due to loss
of lateral support to adjacent columns, forces exerted by falling debris, and load redistribution from other
buckled columns. The exterior columns then buckled as the failed building core moved downward,
redistributing its loads to the exterior columns. Global collapse occurred as the entire building above the
buckled region moved downward as a single unit. This was a fire-induced progressive collapse, also
known as disproportionate collapse, which is defined as the spread of local damage, from an initiating
event, from element to element, eventually resulting in the collapse of an entire structure, or a
disproportionately large part of it.
Factors contributing to the building failure were: thermal expansion occurring at temperatures hundreds
of degrees below those typically considered in design practice for establishing structural fire resistance
ratings; significant magnification of thermal expansion effects due to the long-span floors, which are
common in office buildings in widespread use; connections that were designed to resist gravity loads, but
not thermally induced lateral loads; and a structural system that was not designed to prevent fire-induced
progressive collapse.
The focus is on column 79 buckling. That's the initial local failure. They include a probable collapse sequence, but they don't claim this is the only way it could have happened, nor do they give any degree of confidence beyond the rather vague "likely" and "probable".
2.4 THE PROBABLE COLLAPSE SEQUENCE
The following is the NIST account of how the fires in WTC 7 most likely led to the building's collapse.
...
The initiating local failure that began the probable WTC 7 collapse sequence was the buckling of
Column 79. This buckling arose from a process that occurred at temperatures at or below approximately
400 °C (750 °F), which are well below the temperatures considered in current practice for determining
fire resistance ratings associated with significant loss of steel strength. When steel (or any other metal) is
heated, it expands. If thermal expansion in steel beams is resisted by columns or other steel members,
forces develop in the structural members that can result in buckling of beams or failures of connections.
Fire-induced thermal expansion of the floor system surrounding Column 79 led to the collapse of
Floor 13, which triggered a cascade of floor failures. In this case, the floor beams on the east side of the
building expanded enough that they pushed the girder spanning between Columns 79 and 44 to the west
on the 13th floor. (See Figure 1–5 for column numbering and the locations of girders and beams.) This
movement was enough for the girder to walk off of its support at Column 79.
The unsupported girder and other local fire-induced damage caused Floor 13 to collapse, beginning a
cascade of floor failures down to the 5th floor (which, as noted in Section 1.2.3, was much thicker and
stronger). Many of these floors had already been at least partially weakened by the fires in the vicinity of
Column 79. This left Column 79 with insufficient lateral support, and as a consequence, the column
buckled eastward, becoming the initial local failure for collapse initiation.
Again in chapter 4: Principal Findings:
3.2 THE LEADING HYPOTHESIS
Based on observations and analyses of photographic and video records, critical study of steel framing, and
simplified and detailed analyses to investigate possible failure modes that could lead to an initiating event,
NIST developed the following collapse hypothesis:
• The conditions that led to the collapse of WTC 7 arose from fires, perhaps combined with
structural damage that followed the impact of debris from the collapse of WTC 1. The fires
were fed by ordinary office combustibles.
• The fires on Floors 7 through 13 heated the building structure. Being lighter than the
columns and with thinner SFRM, the floor beams, floor slabs, and connections heated more
quickly and to higher temperatures than the columns. The elevated temperatures in the floor
elements led to their thermal expansion, sagging, and weakening, which resulted in failure of
floor connections and/or buckling of floor beams.
• Sufficient breakdown of connections and/or beams resulted in loss of lateral support and
buckling of at least one of the critical columns supporting a large-span floor bay on the
eastern side of the building on or below Floor 13. This was the initiating event of the
collapse.
• The initial local failure progressed upward to the east penthouse. As the large floor bays
became unable to redistribute the loads, the interior structure below the east penthouse
collapsed into WTC 7.
• Triggered by damage due to the falling debris and loss of lateral support to adjacent interior
columns, the failure progressed westward in the region of Floors 7 through 14, where the
floors had been weakened by fires. This ultimately resulted in the collapse of the entire
structure.
Could the NIST report be better? Yes. Is there going to be another investigation because of this? No.
4.2 SUMMARY
Objective 1:
Determine why and how WTC 7 collapsed.
...
The probable collapse sequence that caused the global collapse of WTC 7 was initiated by the
buckling of Column 79, which was unsupported over nine stories, after local fire-induced
damage led to a cascade of floor failures.
I have given the logical steps that prove NIST is lying about the walk-off of A2001.
Also:
At 400 °C, the floor beams would have expanded 3.3 inches, nowhere near enough to push the A2001 girder off of its seat.“At temperatures less than approximately 400 °C, restrained thermal expansion of beams
and girders caused axial compressive forces to develop in the beams and girders, which
led to the following connection failures:
− bolt shear failure in fin, knife, and seated connections,
− girder walk off of seated connections after all the bolts had sheared at Columns 79
and 81" NCSTAR 1-9, Vol. 2, p. 536 [PDF p. 198/602]
Also:
3. The web stiffeners, that NIST fraudulently omitted, would have prevented the bottom flange from folding, even if the floor beams could push the A2001 girder past its web.
Also:
even if?
ETA: If the girder to the east of column 79 was expanding, the slab would be expanding with it. And together they would push everything to the east. So there would be no net increase of the displacement of the A2001 girder.
