WTC7: Is AE911's (and NIST's) Focus on A2001 Justified if it Was Not "Key" in NIST's Global Model?

[Mick West]

However, we agree that A2001 was not pushed off of its seat.

We do? We that's my point. If, in NIST's LS-DYNA model, A2001 is not pushed off its seat, then the focus of AE911T's study on A2001 is misplaced. As was discussed two years ago.

You are claiming to know better than NIST what triggered the cascade of floor collapses by looking at a video simulation. But they have the failure data and you don’t so your assumption is not valid.

The LS-DYNA model shows that A2001 was not walked off its seat. The preliminary report's diagrams shows A2001 did not walk off its seat (Figure 11-36). The final report's says that A2001 DID walk off its seat, but they did not do new simulations showing what the effect would be. NIST never really explained this change. So maybe someone should ask them about that.

 

[Christopher 7]

While it is true that other failures occurred before A2001 on floor 13

In the context of the Hulsey draft report, which is the context, the topic currently, this is all the facts we need.

No, that is not all we need.

Hulsey focused on the A2001 girder collapse because NIST said that is what triggered the collapse.

11:40 “Next point. Why focus on girder A2001 collapse when NIST did not use that in their global collapse analysis.”

That is simply not true. It may not be clear in the simulation video but NIST was very clear about the failure of A2001 being the trigger that led to the total collapse of the building. They have the data so there is no justification to say otherwise.

 

[Mick West]

Hulsey focused on the A2001 girder collapse because NIST said that is what triggered the collapse.

Even taking that at face value, Hulsey is ignoring all the other damage (which seems a lot more significant in the LS-DYNA).

Before A2001 starts to move there's already SIX similar sided girders and associated floor sections falling, the top ones having a free fall of at least three floors ahead of them

Then by the time A2001 (from floor 13) hits floor 12, there's already significant damage been done

And if you continue the simulation, A2001 stops (and flops around unrealistically, because of limitations in the model), the beams and the slab to the East (right) stop, much of the slab to the West (left) stops, massive destruction continues unrelated to A2001

As far as can be seen here, A2001 does not initially fall off its seat, fails by buckling, not walk-off, and contributes hardly at all to the collapse.

Hulsey models none of this.

 

[Oystein]

No, that is not all we need.

Hulsey focused on the A2001 girder collapse because NIST said that is what triggered the collapse.

You should perhaps keep in mind the three key objectives of the Hulsey report - page 1 of hos draft report:

The objective of this study, therefore, was threefold: (1) Examine the structural response of WTC 7 to fire loads that may have occurred on September 11, 2001; (2) Rule out scenarios that could not have caused the observed collapse; and (3) Identify types of failures and their locations that may have caused the total collapse to occur as observed.

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You will immediately notice that these key objectives do not contain the strings "NIST" nor "A2001", and thus Hulsey would have been misguided to focus solely on NIST and A2001.

Objectives (1) and (3) are entirely unrelated to anything NIST may or could ever have done. His work on those two objectives should not be affected in any way, shape or form by whether NIST has done any work, forwarded any explanations, or what those may have been. Any and all work towards those objectives, if done right, could have been identical if NIST did not even exist.

The only place where NIST enters in is objective (2), where Hulsey intends to review previous studies and explanation, specifically those advanced by NIST, Arup and Weidlinger.

As has been pointed out above, Hulsey must necessarily fail to tackle the Arup hypothesis by his decision not to look at structural response to cooling cycles, and must necessarily fail to tackle the Weidlinger hypothesis by ignoring on purpose any and all structural responses to any and all fires at and near floors 9 and 10.

So he's left with the NIST report.

Now YOU, Chris, admitted that "it is true that other failures occurred before A2001 on floor 13" - in the NIST simulations as well as in reality (I presume you were thinking of the former). Those other failures are then the necessary context for assessing what happens when A2001, too, fails.
Hulsey chose to ignore that context.
By this choice, he failed his objective by default.

And these are all the reasons we need to recommend that the study and draft report be binned entirely, and be reset to zero - start anew.

 

[Christopher 7]

Hulsey focused on the A2001 girder collapse because NIST said that is what triggered the collapse.

Even taking that at face value, Hulsey is ignoring all the other damage (which seems a lot more significant in the LS-DYNA).

Before A2001 starts to move there's already SIX similar sided girders and associated floor sections falling, the top ones having a free fall of at least three floors ahead of them

True. (except for the free fall part - but that is not relevant to the crux of this disagreement)

Then by the time A2001 (from floor 13) hits floor 12, there's already significant damage been done

And if you continue the simulation, A2001 stops (and flops around unrealistically, because of limitations in the model), the beams and the slab to the East (right) stop, much of the slab to the West (left) stops, massive destruction continues unrelated to A2001

All true except for the floor area to the north-west of column 79. I found a quote that confirms what I have been saying. Although floor 14 collapsed before A2001 on floor 13 and did more damage, it was the collapse of the A2001 girder on floor 13 that triggered the initiating event, the buckling of column 79.

The simple shear connection between Column 79 and the girder that spanned the distance to the north face (to Column 44) failed on Floor 13. The connection failed due to shearing of erection bolts, caused by lateral thermal expansion of floor beams supporting the northeast floor system and, to a lesser extent, by the thermal expansion of the girder connecting Columns 79 and 44. Further thermal expansion of the floor beams pushed the girder off its seat, which led to the failure of the floor system surrounding Column 79 on Floor 13. The collapse of Floor 13 onto the floors below—some of which were already weakened by fires—triggered a cascade of floor failures in the northeast region. This, in turn, led to loss of lateral support to Column 79 in the east-west direction over nine stories (between Floors 5 and 14). The increase in unsupported length led to the buckling failure of Column 79, which was the collapse initiation event. NCSTAR 1-9 Vol. 2 p. 611 [PDF p. 273/677]

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Note that it says "led to loss of lateral support to Column 79 in the east-west direction." That is consistent with what I have been saying. The collapse of floor 14 took out the girders and floor areas to the south of column 79. But the coup de grâce was the failure of floor 13 that started a cascade of floor failures which took out the girders supporting column 79 on the west side, leaving column 79 unsupported in three directions over nine floors.

This is relevant to the Hulsey report in that I am rebutting Mick's comment about that report:

11:40 “Next point. Why focus on girder A2001 collapse when NIST did not use that in their global collapse analysis.”

Hulsey's report focused on A2001 in floor 13 because NIST said that was the triggering event.

The quote from the NIST final report on WTC 7 above confirms that NIST did use the collapse of A2001 in the global collapse analysis (but the video doesn't show it precisely).

Without the triggering and the ensuing initiating events, there would have been no progressive collapse.

 

[econ41]

Agreed Oystein.
I would also identify another level of problem.

The project has from the earliest statements made by Hulsey been fatally flawed by invalid global claims. The most serious probably the claim - stated in various ways - that the project can would prove or has proved "Fire could not cause the collapse of WTC7". That is a global negative claim which cannot be proved in the context of the Hulsey study.

And the same problem of "global claims" is apparent in the quoted objectives which are:

The objective of this study, therefore, was threefold: (1) Examine the structural response of WTC 7 to fire loads that may have occurred on September 11, 2001; (2) Rule out scenarios that could not have caused the observed collapse; and (3) Identify types of failures and their locations that may have caused the total collapse to occur as observed.

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All three omit the essential qualifier "some".

If atated: "(1) Examine the structural response of WTC 7 to SOME fire loads that may have occurred on September 11, 2001; (2) Rule SOME out scenarios that could not have caused the observed collapse; and (3) Identify SOME types of failures and their locations that may have caused the total collapse to occur as observed." ... then the objectives are valid. But even if Hulsey can satisfy those valid objectives it still does not "prove" the main global claim of "Fire could not cause...."

 

[Oystein]

...
Hulsey's report focused on A2001 in floor 13 because NIST said that was the triggering event.
...

No, it (the report) does not focus on A2001 - only a minor part of it may.
But even if it did, it has been pointed out to you already several times that focussing on a single girder is not valid, cannot possibly be valid, if it ignores, on purpose and by design, any and all other connection and other damages incurred by hours of fire development on much more than just two floors. Which is what Hulsey did: Ignore high temperatures on most floors, ignore fire development (regionally differentially, heating and cooling), ignore practically all other connection damages.

NIST may have focused their discussion in SOME subsections of their hundreds of pages of detailed analysis on girder A2001, but they did so always in the CONTEXT of all other damages - and all the other sections of the NIST reports document all the other failures.

And of course the final, global collapse analysis with LS-DYNA, as Mick has shown to you with great clarity, progresses because there are so many other things going on that you and Hulsey deliberately ignore.

You need to stop ignoring all the other fire damage.

 

[Christopher 7]

Hulsey focused on the A2001 girder collapse because NIST said that is what triggered the collapse.

No, it (the report) does not focus on A2001 - only a minor part of it may.

I was responding to a statement Mick made in his video “Some Problems with the UAF/Hulsey/AE911Truth WTC7 Draft Report”.

11:40 “Next point. Why focus on girder A2001 collapse when NIST did not use that in their global collapse analysis.”

I have shown that Mick's statement is incorrect. NIST did use the collapse of the A2001 girder in their global collapse analysis.

But even if it did, it has been pointed out to you already several times that focussing on a single girder is not valid, cannot possibly be valid, if it ignores, on purpose and by design, any and all other connection and other damages incurred by hours of fire development on much more than just two floors. Which is what Hulsey did: Ignore high temperatures on most floors, ignore fire development (regionally differentially, heating and cooling), ignore practically all other connection damages.

Although other damage caused column 79 to be unsupported in the south direction, all the other damage did not leave column 79 unsupported in three directions over nine floors and did not cause the building to collapse. Without the push-off of A2001 at column 79 on floor 13, there would have been NO initiating event and NO global collapse. That is why that single girder is so important.

The floor framing structure was thermally weakened at Floors 8 to 14, with the most substantial fire-induced damage occurring in the east region of Floors 12, 13 and 14. Even though each floor had been weakened over hours of exposure to separate and independent fires, it was not until there was substantial damage to the long span floors in the northeast region of Floor 13 that the initial failure event, i.e., the buckling of Column 79 was triggered. NCSTAR 1-9, Vol. 2, p. 572 [PDF p. 234/638]

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[Jeffrey Orling]

Tell me again... How can anyone know exactly where the structural failures WAS (singular) not were... plural which was the trigger of the global collapse? The clues I see were the drop of the EPH... some distortion of reflections on the facade glass.... smoke and flames seen from the exterior (mostly viewed from the north)?

Another oddity (to me) which I never see discussed... is what started the "massive fires" and where was that? For example why the region around col 79 in the low teens which is the region NIST discusses?

It appears to me that all of these collapse musings and forensics are largely based more on (not unreasonable) assumptions and theoretical models and less on data. There are several axial lines of support (76. 77. 78. 79, 80 & 81) under the EPH and any of them failing would lead to the structure (EPH) above collapsing down leading to what was observed. However, col 79 looks like it carries the largest single axial load of the columns below the EPH. ref pages 12-17 appendix to the NIST report.

 

[Joe Hill]

Without the push-off of A2001 at column 79 on floor 13, there would have been NO initiating event and NO global collapse.

Why "push-off", as if that's the only option? Could A2001 not have been "pulled" off it's Column 79 connection?

 

[Christopher 7]

Rebuttal to comments in “Some Problems with the UAF/Hulsey/AE911Truth WTC7 Draft Report”

11:40 “Next point. Why focus on girder A2001 collapse when NIST did not use that in their global collapse analysis.”

Here are more quotes that confirm NIST did use the collapse of girder A2001 on floor 13 as the trigger of the global collapse. (see post 188 for my first NIST quote confirming that NIST did use the collapse of girder A2001 on floor 13 as the trigger of the global collapse.)

girders between Columns 44 and 79 and Column 26 and 81 failed due to girder walk off of the bearing seat NCSTAR 1-9, Vol. 2, p. 537 [PDF p. 199/603]

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The collapse of Floor 13 onto the floors below, some of which were already weakened by fires, triggered a cascade of floor failures in the northeast region of the building.

The floor failures progressed down to Floor 5, where debris accumulated, and spread across the east floor area, due to the effects of impact loads from falling debris on thermally weakened floor areas.

Critical Column 79 became laterally unsupported between Floors 5 and 14 in the east-west and south directions as a result of the progression of floor system failures. NCSTAR 1-9, Vol. 2 p. 604 [PDF p. 266/670]

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Initial Local Failure for Collapse Initiation. Fire-induced thermal expansion of the floor system surrounding Column 79 led to collapse of Floor 13 that triggered a cascade of floor failures. This, in turn, led to loss of lateral support to Column 79 over nine stories, resulting in the buckling failure of Column 79. NCSTAR 1-9, Vol. 2 p. 609 [PDF p. 271/675]

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We agree that the video model appears to show that the A2001 girder on the 13th floor fails due to sagging but the text of the final report says that it was due to A2001 on the 13th floor being pushed off of its seat.

 

[Mick West]

Here are more quotes that confirm NIST did use the collapse of girder A2001 on floor 13 as the trigger of the global collapse.

Critical Column 79 became laterally unsupported between Floors 5 and 14 in the east-west and south directions as a result of the progression of floor system failures. NCSTAR 1-9, Vol. 2 p. 604 [PDF p. 266/670]

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A2001 is to the NORTH of Column 79. So how would a collapse to the north trigger floor failures to the east-west and south, but not in the north.

 

[Christopher 7]

A2001 is to the NORTH of Column 79. So how would a collapse to the north trigger floor failures to the east-west and south, but not in the north.

I already explained this.

Since the collapse of floor 14 caused the collapse of the floors to the south of column 79, and the floors to the east of column 79 did not collapse on floors 12-8 until column 79 buckled, then all that’s left is the floors and girders to the West of A2001 of floor 13 that could have collapsed due to the failure of A2001 on floor 13. This, according to NIST, is the last straw that left column 79 unsupported in three directions over nine floors – and it buckled.

And I followed up with this:

I found a quote that confirms what I have been saying. Although floor 14 collapsed before A2001 on floor 13 and did more damage, it was the collapse of the A2001 girder on floor 13 that triggered the initiating event, the buckling of column 79.

The simple shear connection between Column 79 and the girder that spanned the distance to the north face (to Column 44) failed on Floor 13. The connection failed due to shearing of erection bolts, caused by lateral thermal expansion of floor beams supporting the northeast floor system and, to a lesser extent, by the thermal expansion of the girder connecting Columns 79 and 44. Further thermal expansion of the floor beams pushed the girder off its seat, which led to the failure of the floor system surrounding Column 79 on Floor 13. The collapse of Floor 13 onto the floors below—some of which were already weakened by fires—triggered a cascade of floor failures in the northeast region. This, in turn, led to loss of lateral support to Column 79 in the east-west direction over nine stories (between Floors 5 and 14). The increase in unsupported length led to the buckling failure of Column 79, which was the collapse initiation event. NCSTAR 1-9 Vol. 2 p. 611 [PDF p. 273/677]

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Note that it says "led to loss of lateral support to Column 79 in the east-west direction." That is consistent with what I have been saying. The collapse of floor 14 took out the girders and floor areas to the south of column 79. But the coup de grâce was the failure of floor 13 that started a cascade of floor failures which took out the girders supporting column 79 on the west side, leaving column 79 unsupported in three directions over nine floors.

I read Chapter 12 again and found this:

The global simulation was first initialized under gravity loading over 4.5 s of simulation time. Then damage and temperature initialization states were applied over 4 additional seconds. Collapse propagation in the global model required approximately 16 additional seconds after initialization, for a total of about 25 s of simulated time NCSTAR 1-9, Vol. 2, p. 544 [PDF p. 206/610]

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12.3.2 Model Initialization and Loading Sequence
Last, the fire-induced damage obtained from the 16 story ANSYS analysis, including damage to floor beams, girders, and connections, was applied instantaneously. The heated, damaged structure was then free to react. NCSTAR 1-9, Vol. 2, p. 563 [PDF p. 225/629]

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We have been thinking that the LS-DYNA analysis and the global simulation were the same but they are not. The LS-DYNA model had the damage applied instantaneously but the simulation had the damage applied over a period of 4 seconds.

I admitted that I was wrong about Hulsey getting the ANSYS and LS-DYNA models mixed up. Now I would like you to admit that you were wrong about NIST not using A2001 being pushed off of its seat on floor 13 in their global collapse analysis.

 

[Jeffrey Orling]

Here are more quotes that confirm NIST did use the collapse of girder A2001 on floor 13 as the trigger of the global collapse. (see post 188 for my first NIST quote confirming that NIST did use the collapse of girder A2001 on floor 13 as the trigger of the global collapse.)

girders between Columns 44 and 79 and Column 26 and 81 failed due to girder walk off of the bearing seat NCSTAR 1-9, Vol. 2, p. 537 [PDF p. 199/603]

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The collapse of Floor 13 onto the floors below, some of which were already weakened by fires, triggered a cascade of floor failures in the northeast region of the building.

The floor failures progressed down to Floor 5, where debris accumulated, and spread across the east floor area, due to the effects of impact loads from falling debris on thermally weakened floor areas.

Critical Column 79 became laterally unsupported between Floors 5 and 14 in the east-west and south directions as a result of the progression of floor system failures. NCSTAR 1-9, Vol. 2 p. 604 [PDF p. 266/670]

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Initial Local Failure for Collapse Initiation. Fire-induced thermal expansion of the floor system surrounding Column 79 led to collapse of Floor 13 that triggered a cascade of floor failures. This, in turn, led to loss of lateral support to Column 79 over nine stories, resulting in the buckling failure of Column 79. NCSTAR 1-9, Vol. 2 p. 609 [PDF p. 271/675]

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We agree that the video model appears to show that the A2001 girder on the 13th floor fails due to sagging but the text of the final report says that it was due to A2001 on the 13th floor being pushed off of its seat.

Sagging per se is not a failure. Every loaded beam sags - deflects. Too much deflection is not acceptable but may not be a mechanical failure. The matter needs to be framed as what would be the mechanical implication of excessive sagging. How does excessive deflection impact the end/bearing of the beam. Does it lead to the beam to column connection failure? Or does it lose so much capacity that it buckles?

 

[Mick West]

I read Chapter 12 again and found this:

The global simulation was first initialized under gravity loading over 4.5 s of simulation time. Then damage and temperature initialization states were applied over 4 additional seconds. Collapse propagation in the global model required approximately 16 additional seconds after initialization, for a total of about 25 s of simulated time NCSTAR 1-9, Vol. 2, p. 544 [PDF p. 206/610]

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​

12.3.2 Model Initialization and Loading Sequence
Last, the fire-induced damage obtained from the 16 story ANSYS analysis, including damage to floor beams, girders, and connections, was applied instantaneously. The heated, damaged structure was then free to react. NCSTAR 1-9, Vol. 2, p. 563 [PDF p. 225/629]

​

We have been thinking that the LS-DYNA analysis and the global simulation were the same but they are not. The LS-DYNA model had the damage applied instantaneously but the simulation had the damage applied over a period of 4 seconds.

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This is entirely incorrect. The global simulation IS the LS-DYNA model being referred to here. You are taking a small part of 12.3.2 out of context. The full section is:

12.3.2 Model Initialization and Loading Sequence
The global model was initialized as follows to minimize any dynamic effects associated with loading
sequence.

• First, gravity was applied slowly to the 47 floor structure over 4.5 s of elapsed simulation
time to damp residual vibrations and eliminate dynamic response. The loads were applied
smoothly with a sinusoidal load curve.

• Then, the debris impact damage from the collapse of WTC 1 was applied to the structure
instantaneously by removing damaged elements from the model that were no longer capable
of bearing their loads. The structure was then allowed to damp residual vibrations for 2 s.

• Next, the structural temperatures were applied smoothly with a sinusoidal curve and allowed
to damp residual vibrations for 2 s.

• Last, the fire-induced damage obtained from the 16 story ANSYS analysis, including damage
to floor beams, girders, and connections, was applied instantaneously. The heated, damaged
structure was then free to react.

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This is the exact same 4.5 + 4 initialization and damage application as from your earlier quote (which is from section 12.2.2). The 4 seconds comes from the 2 seconds of settling after debris damage application plus the 2 seconds of temperature application and continued settling. This differs from the 4.5 seconds, which is a gradual application of gravity.

No settling period is needed after the sudden application of the ANSYS damage, because "settling" is just running the simulation, which in this case is the building collapsing. This all is illustrated in the figure 12-32

After section 12.3.4 there's a more detailed description, of how this all works. Section 12.4.4 then describes in detail how this led to the buckling of C79, without mentioning the walk-off (which, as was discussed years ago, is in a different part of the report, and possibly refers to model runs that were not shown)

Global model = Global Simulation = LS-DYNA simulation - in which A2001 appears to buckle, and not fail at the C79 connection

 

[Christopher 7]

A2001 is to the NORTH of Column 79. So how would a collapse to the north trigger floor failures to the east-west and south, but not in the north.

You did not dispute this part:

Since the collapse of floor 14 caused the collapse of the floors to the south of column 79, and the floors to the east of column 79 did not collapse on floors 12-8 until column 79 buckled, then all that’s left is the floors and girders to the West of A2001 on floor 13 that could have collapsed due to the failure of A2001 on floor 13. This, according to NIST, is the last straw that left column 79 unsupported in three directions over nine floors – and it buckled

I found a quote that confirms what I have been saying. Although floor 14 collapsed before A2001 on floor 13 and did more damage, it was the collapse of the A2001 girder on floor 13 that triggered the initiating event, the buckling of column 79.

The simple shear connection between Column 79 and the girder that spanned the distance to the north face (to Column 44) failed on Floor 13. The connection failed due to shearing of erection bolts, caused by lateral thermal expansion of floor beams supporting the northeast floor system and, to a lesser extent, by the thermal expansion of the girder connecting Columns 79 and 44. Further thermal expansion of the floor beams pushed the girder off its seat, which led to the failure of the floor system surrounding Column 79 on Floor 13. The collapse of Floor 13 onto the floors below—some of which were already weakened by fires—triggered a cascade of floor failures in the northeast region. This, in turn, led to loss of lateral support to Column 79 in the east-west direction over nine stories (between Floors 5 and 14). The increase in unsupported length led to the buckling failure of Column 79, which was the collapse initiation event. NCSTAR 1-9 Vol. 2 p. 611 [PDF p. 273/677]

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Note that it says "led to loss of lateral support to Column 79 in the east-west direction." That is consistent with what I have been saying. The collapse of floor 14 took out the girders and floor areas to the south of column 79. But the coup de grâce was the failure of floor 13 that started a cascade of floor failures which took out the girders supporting column 79 on the west side, leaving column 79 unsupported in three directions over nine floors.

In other words, NIST did use the failure of A2001 on the 13th floor in their final analysis and it was the trigger that led to the initiating event - the buckling of column 79.

 

[Christopher 7]

In the video simulation, the A2001 girder on floor 13 is doing something it could not do in reality. It's sagging several feet, but that is impossible. A spreadsheet for the floor beams in the NE corner of the 13th floor shows elongation vs sag. Since loads are proportional, the sag of the girder would be roughly the same as the floor beams for any given temperature. The sag (noted on the right as deflection) at 600°C is 5-1/2 inches.

Figure 10-39 shows that the A2001 girder on floor 13 never got above about 450°C.

 

[Oystein]

In the video simulation, the A2001 girder on floor 13 is doing something it could not do in reality.

By "in reality" you actually mean "in some other model", right?

It's sagging several feet, but that is impossible. A spreadsheet for the floor beams in the NE corner of the 13th floor shows elongation vs sag. Since loads are proportional, the sag of the girder would be roughly the same as the floor beams for any given temperature. The sag (noted on the right as deflection) at 600°C is 5-1/2 inches.

View attachment 39240
...

Where is that spreadsheet from?

 

[Christopher 7]

The global simulation was first initialized under gravity loading over 4.5 s of simulation time. Then damage and temperature initialization states were applied over 4 additional seconds. Collapse propagation in the global model required approximately 16 additional seconds after initialization, for a total of about 25 s of simulated time NCSTAR 1-9, Vol. 2, p. 544 [PDF p. 206/610]

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This is the exact same 4.5 + 4 initialization and damage application as from your earlier quote (which is from section 12.2.2). The 4 seconds comes from the 2 seconds of settling after debris damage application plus the 2 seconds of temperature application and continued settling. This differs from the 4.5 seconds, which is a gradual application of gravity.

It could be interpreted as the same 4 seconds except for the sequential collapses in the simulation. Had the damage from the ANSYS model been applied instantaneously, everything would have collapsed at the same time. But that is not what happens in the simulation. The collapses happen over a period of several seconds as would be the case if the damage from the ANSYS model were applied over a period of 4 seconds.

There is a subtle difference in the two initialization quotes. The LS-DYNA model initialization specifies damage from WTC 1 but the global simulation does not. This leaves open the possibility that the damage applied in those 4 seconds included the damage from the ANSYS model, which appears to be the case.

12.3.2 Model Initialization and Loading Sequence
...
Then, the debris impact damage from the collapse of WTC 1 was applied to the structure
instantaneously

The global simulation was first initialized under gravity loading over 4.5 s of simulation time. Then damage and temperature initialization states were applied over 4 additional seconds.

You did not dispute my comment in post #96. Are you willing to admit that NIST did use the collapse of A2001 on the 13th floor in their final analysis?

 

[Christopher 7]

By "in reality" you actually mean "in some other model", right?

No. I mean "in the NIST report" as noted in Figure 10-39.
There is no other model in the NIST report.
In NIST's ANSYS analysis, the beams and girders failed at temperatures at or below 400 °C.

“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)” NCSTAR 1A, p. 21 [PDF p. 63]

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The spreadsheet was made by Tony Szamboti and David Chandler.

 

[Mick West]

Are you willing to admit that NIST did use the collapse of A2001 on the 13th floor in their final analysis?

Well, that depends on what you mean by "final analysis" - my point in this thread is that they did not use the A2001 walk-off in the global LS-DYNA model runs that they show in their report. You can clearly see the connection does not fail via walk-off, it fails via some failure the girder itself.

The reality of the girder failures via buckling is a different issue. The question at hand is if "Is AE911's (and NIST's) Focus on A2001 Justified if it Was Not "Key" in NIST's Global Model?"