OOS Collapse Propagation Model

[femr2]

The answer is that it did not tilt at all before collectively falling downward. Because any such tilt requires the center of gravity to move downward, and what other possible meaning could "collectively falling downward" have besides downward movement of the center of gravity?

The angle is determined by tracing numerous features, such as the NW corner, elements of the antenna, and points on the upper section on the south side. Cross-referencing between several pieces of footage has also been necessary.

Vertical movement of the NW corner *lags* vertical movement of other features (at very low level, it's not a definitive lag, but a much much lower rate of movement. Noise in the data cannot be removed entirely). The angle is determined by determining the point at which vertical movement of the NW corner *begins*, and referencing with other features.

That is, unless someone is claiming that the top section first tilted like a seesaw. One side tilting down, and the other side moving upward, around a fulcrum in the middle, so that the center of gravity did not drop.

You're not far off there. Yes, there appears to be *very* slight upward motion of the NW corner at initiation. I'll put a graph together to highlight.

there was no structural portion of the towers that could be a strong enough or rigid enough lever arm for seesaw tilting, even if the core were capable of serving as a fulcrum.

It's *very* slight upward motion, but the NW corner *lag* is much easier to identify. From the data I have, core failure preceeds south face failure.

How could NIST state south face failure led to subsequent failures if such did not preceed the subsequent failures ?

Did NIST use the exact same time reference for their supposed 8% figure?

NIST state 8 degree rotation before vertical drop of the upper block.
You are saying ZERO degrees before vertical drop.
I am saying ~1 degree before vertical drop.

Who is right ? NIST certainly are not.

Rotation did not stop entirely at that point of course, and it looks like the upper section rapidly deformed and broke apart shortly after initiation.

 

[DavidJames]

DavidJames,

What angle did the upper block rotate through before collective downward motion ensued ?

Where did NIST state the initial failure occurred ?

If you are suitably capable, why not apply your time to development of the equations of motion required to complete to OOS study, rather than pointless whining ?

Have you not submitted your own papers ? I assume they will/have highlighted the gross errors within the NIST report. If not, why not ? I assume it's not news to you that the NIST answer to Q1 above was far from accurate, so I assume you've pointed it out before, and stated the implications of that error, yes ? Please point me to your post/papers where you highlight such. Ta.

I haven't submitted any papers because I'm not rambling on about engineering problems. Please address my point. Are you an uneducated Internet buffoon, posting about something you aren't qualified to discuss or educated coward, someone who is knowledgeable but refuses to publish, which is?

Save us the trouble, if you're not going to answer the question, don't bother responding.

 

[sheeplesnshills]

What did he do to rule out cd that he did not do for Mothra?

It was Kong I tell you!

 

[sheeplesnshills]

Who showed WTC1 collapse initiation was inevitable? (WTC1 was hit on the north side but failed southwards.) You believe the NIST proved that?

NIST showed one possible mechanism, The buildings, impacts and fires have many many variables and to expect them to match exactly is unrealistic.
Until you can show evidence of explosives being used or indisputable evidence that impact and fires alone could not cause the collapses you are wasting your time on irrelevancies.

I look forward to you presenting that evidence.

 

[beachnut]

Do you have any way to prove that ?

(I've seen too many of your rambling and repetative posts to have any respect for your opinion. OCD if you ask me.)

Prove AP was not used? It would leave evidence; there is no evidence of AP. Done, no AP was used to bring down the WTC towers. I am right and you will never refute the evidence. It is so easy to prove your ideas are garbage on 911.

The OOS collapse model paper is garbage as Major Tom is obsessed with attacking Bazant's model due to his zero engineering skills and lack of knowledge of what a model is and means. Putting CD in the conclusion is nonsense. You CD theory guys have failed because there is no evidence. It is extremely ironic gravity is the prime mover in CD. 911 truth has zero skills in engineering and physics to help them prove their idiotic delusions of CD. The OOS model fails due to delusions in the conclusions.

 

[pgimeno]

It was Kong I tell you!

No, you Kong believers are a discredit for the Movement for Mothra Truth! Noone serious enough would buy that Kong theory, which is just a distraction from the real, unavoidable truth: Mothra did 9/11. I know you have videos that you think support your theory, but when you examine them carefully, it's obvious that what you're looking is the effect of Mothra's action.

 

[Major_Tom]

Myriad writes: "The answer is that it did not tilt at all before collectively falling downward. Because any such tilt requires the center of gravity to move downward, and what other possible meaning could "collectively falling downward" have besides downward movement of the center of gravity?"

I'll be using a 5 stage approach just as Bazant does in BZ. My stages are similar to Bazant but reworded slightly:

stage 1) Airplane damage, fuel and fires

stage 2) Visible deformations leading into initial buckling sequence, especially inward bowing (IB) of the south face.

stage 3) Initial buckling sequence (initial lateral propagation of column failure and trajectory over the first 12 ft.

stage 4) Initial collision and resulting trajectory and behavior through subsequent collisions

stage 5) Runaway collapse propagation (ROOSD)

What we are talking about is stage 3 (initial buckling sequence). This stage begins with the first visible movement of the building during initiation and ends when the last column is buckled.

For WTC1 we can see when the last columns are buckled since they were from the NW corner,. which is clearly visible in a few clips and is not covered by smoke or dust. We can see when the NW corner gave almost to the frame (in 60 frame per second video).

It has nothing to do with movement of the center of gravity. I use the term "collective downward movement" to be movement which occurs after the NW corner has failed. All columns must fail before the whole top can be considered to move downward.

Myriad writes: "So, assuming we're all agreed that seesaw tilting was neither realistically expected nor observed, any observable tilting and the collective falling downward (downward movement of the center of gravity of the upper section) must have started at the same moment."

No seesaw. The closest thing to a rigid model would be a movement of pure rotational motion around an axis going through the 98th floor, north wall, until the "hinge" fails.

In an overly simplified rigid model of collapse initiation, center of gravity can move downwards while the "upper block" is in pure rotational motion. When the "hinge breaks" there is no longer a pivot point so "collective downward motion" can commence.

For a simplified rigid model, in order of occurance:

1) no movement
2) pure rotational movement around the 98th floor north wall until the "pivot" breaks
3) collective downward movement

Initial column failure sequence happens during the second part. Center of mass will be falling at this time so movement of the center of mass is different from the movement after the "hinge" breaks.

A non-rigid model is much more realistic and complex, but clearly the initial buckling sequence terminates when the NW corner fails, so the same principles apply.


Myriad writes in conclusion: "So what Major Tom is arguing about is the amount of tilting that existed at a certain poorly defined time marker, that being the start of a "collective falling downward" which is somehow not indicated by the start of falling of the center of gravity but by something else that happened later. Tom, how is the start of what you consider "collective falling downward" defined and measured for your 1% figure? Did NIST use the exact same time reference for their supposed 8% figure? If not, then you're comparing the states at two different times so it's no surprise that they are different.

The obvious reference point is when the NW corner fails, which is very visible and knowable to within a few frames.

The NIST figure of 8 degree tilt before collective downward movement is so bad there is no way to justify the mistake. Myriad, why don't you show how the NIST calculates the 8 degree tilt by using the NIST reports? Why ask me?

There is no way to justify such a large mistake whough from my experiences in this thread some of you will try to explain it.

But most of you will just ignore the mistake and call me names instead.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>


So, let's put these 2 ideas together:

1) All 47 core columns are already "cut" along the exact same elevation about 3 ft up fro the 98th floor slab. The unwelded connections are held together by 2 bolted plates only.

2) All core and perimeter columns "failed" after the top section had tilted only 1 degree (less but I am being generous) even though the NIST states that during the initial buckling sequence, they failed over an 8 degree tilt.


If we agree on these 2 statements it seems a good place to start an independent study of WTC1 collapse initiation. Agreed?

 

[pgimeno]

2) All core and perimeter columns "failed" after the top section had tilted only 1 degree (less but I am being generous) even though the NIST states that during the initial buckling sequence, they failed over an 8 degree tilt.

(Emphasis added). That's not my reading of NIST. From NCSTAR 1-6D p. 314 (378 of the PDF):

The section of the building above the impact zone tilted to the south (observed at about 8°, Table 5-2) as column instability progressed rapidly from the south wall to the adjacent east and west walls (see Fig. 5-8), resulting in increased gravity load on the core columns.
​

(Emphasis added again). From my reading, they DON'T say that the perimeter columns failed over an 8° tilt.

 

[Seymour Butz]

1) The unwelded connections are held together by 2 bolted plates only.

If we agree on these 2 statements it seems a good place to start an independent study of WTC1 collapse initiation. Agreed?

Since this is wrong, the answer is....... no.

http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR 1-2.pdf

p. 101 or 215/462

States that, "Core perimeter beams were joined with splice plates in the *SAME* manner as the wide flange columns described above." (where they describe the core columns and their connections) and then says, "..... and was appropriate for modeling strong welded connections."

Figure 5-8 shows the details of a box column to wide flange column transition. Welded. Not bolted.

Figure 5-7 shows detail of wf to wf connections. Welded. Not bolted.

 

[dafydd]

Yes, do let's stay on topic. Would Major_Tom and / or femr2 please enlighten us as to their hypothesis that better explains the events of 9/11/01?

I have posed that question to many a truther here and never recieved an answer.

 

[Major_Tom]

Pgimeno writes: "(Emphasis added). That's not my reading of NIST. From NCSTAR 1-6D p. 314 (378 of the PDF):

The section of the building above the impact zone tilted to the south (observed at about 8°, Table 5-2) as column instability progressed rapidly from the south wall to the adjacent east and west walls (see Fig. 5-8), resulting in increased gravity load on the core columns.

(Emphasis added again). From my reading, they DON'T say that the perimeter columns failed over an 8° tilt."

How do you interpret that? That the core columns successively failed over that amount of tilt? The perimeter columns would require even more tilt?

Here is a cleaned-up video taken from the west. This is a good clip to estimate the angle of tilting over which the initial failure sequence takes place. Please hold an object at about 8 or 10 degrees over the screen and you can see without taking a single measurement that the NIST claims of an 8 degree tilt over which the columns originally failed is way, way off. There is very little tilt during the initial column failure sequence.

http://www.youtube.com/user/femr2?&MMN_position=312:312#p/u/2/3Syq4HebZvw


Please recall the following comments by the NIST concerning an 8 degree tilt for WTC1:

1-6D, p 312:

Table 5–1. Summary of main events that led to the collapse of WTC 1.
Event Number........ Event
1 .......................Aircraft impact
2 .......................Unloading of core
3 .......................Sagging of floors and floor/wall disconnections
4........................Bowing of the south wall
5 .......................Buckling of south wall and collapse initiation

1-6D, pg 314:

Bowing of South Wall

The exterior columns on the south wall bowed inward as they were subjected to high temperatures, pull-in forces from the floors beginning at 80 min, and additional gravity loads redistributed from the core. Figure 5–6 shows the observed and the estimated inward bowing of the south wall at 97 min after impact (10:23 a.m.). Since no bowing was observed on the south wall at 69 min (9:55 a.m.), as shown in Table 5–2, it is estimated that the south wall began to bow inward at around 80 min when the floors on the south side began to substantially sag. The inward bowing of the south wall increased with time due to
continuing floor sagging and increased temperatures on the south wall as shown in Figs. 4–42 and 5–7. At 97 min (10:23 a.m.), the maximum bowing observed was about 55 in. (see Fig. 5–6).

Buckling of South Wall and Collapse Initiation

With continuously increased bowing, as more columns buckled, the entire width of the south wall buckled inward. Instability started at the center of the south wall and rapidly progressed horizontally toward the sides. As a result of the buckling of the south wall, the south wall significantly unloaded (Fig. 5–3),
redistributing its load to the softened core through the hat truss and to the south side of the east and west walls through the spandrels. The onset of this load redistribution can be found in the total column loads in the WTC 1 global model at 100 min in the bottom line of Table 5–3. At 100 min, the north, east, and
west walls at Floor 98 carried about 7 percent, 35 percent, and 30 percent more gravity loads than the state after impact, and the south wall and the core carried about 7 percent and 20 percent less loads, respectively. The section of the building above the impact zone tilted to the south (observed at about 8°,
Table 5–2) as column instability progressed rapidly from the south wall along the adjacent east and west walls (see Fig. 5–8), resulting in increased gravity load on the core columns. The release of 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 ensued.

1-6draft, p 288, Table 9-5 titled "Observations for WTC1", fifth entry:
and
1-6D, p 312, Table 5-2, last entry

Tower began to collapse – first exterior sign of collapse was at
Floor 98. Rotation of at least 8 degrees to the south occurred before
the building section began to fall vertically under gravity.

1-6draft p 290, figure 9-8 on probable collapse initiation sequence for WTC1:

3. 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.

1-6draft, p 294:

Buckling of South Wall and Collapse Initiation

The inward bowing of the south wall increased as the post-buckling strength of bowed columns continued to reduce. The bowed columns increased the loads on the unbuckled columns on the south wall by shear transfer through the spandrels. Consequently instability progressed horizontally, and when it engulfed the entire south wall, it progressed along the east and west walls. Moreover, the unloading of the south wall resulted in further redistribution of gravity loads on the south wall to the east and west walls and to the thermally weakened core via the hat truss. At 100 min, the north, the east, and the west walls at Floor 98 carried about 7 percent, 35 percent, and 30 percent more gravity loads than the state after impact, and the south wall and the core carried about 7 percent and 20 percent less loads, respectively. The section of the building above the impact zone began tilting to the south at least about 8° as column instability progressed rapidly from the south wall along the adjacent east and west walls, as shown in Fig. 9–13. The change in potential energy due to downward movement of building mass above the buckled columns exceeded the strain energy that could have been absorbed by the structure. Global collapse ensued.

1-6draft, p 317:

Finding 26: The WTC 1 building section above the impact and fire area tilted to the south as the structural collapse initiated. The tilt was toward the side of the building that had the long span floors. Video records taken from east and west viewpoints showed that the upper building section tilted to the south. Video records taken from a north viewpoint showed no discernable east or west component in the tilt. A tilt to the south of at least 8 degrees occurred before dust clouds obscured the view and the building section began to fall downwards.

Isn't is obvious that the angle is much, much smaller than 8 degrees before taking your first measurement?

 

[Sam.I.Am]

1-6draft

I can't understand why people do this when the final report is available.

 

[Major_Tom]

Identical in the final report or I wouldn't post it. I can copy and paste from the draft version but I cannot from the final report.

That is the only difference.

 

[pgimeno]

Pgimeno writes: "(Emphasis added). That's not my reading of NIST. From NCSTAR 1-6D p. 314 (378 of the PDF):

The section of the building above the impact zone tilted to the south (observed at about 8°, Table 5-2) as column instability progressed rapidly from the south wall to the adjacent east and west walls (see Fig. 5-8), resulting in increased gravity load on the core columns.
​

(Emphasis added again). From my reading, they DON'T say that the perimeter columns failed over an 8° tilt."

How do you interpret that? That the core columns successively failed over that amount of tilt? The perimeter columns would require even more tilt?

(Re-added the

tags that I put and you removed, to make it clear what the cite is, as well as the emphasis that you also removed - please don't modify my formatting when quoting me.)

I interpret the expression "column instability" as columns failing. If that's the case, and I believe it's a strong case, you have no basis to claim that NIST is saying that the perimeter columns failed only after the 8° tilt.

Here is a cleaned-up video taken from the west. This is a good clip to estimate the angle of tilting over which the initial failure sequence takes place. Please hold an object at about 8 or 10 degrees over the screen and you can see without taking a single measurement that the NIST claims of an 8 degree tilt over which the columns originally failed is way, way off.

You're again making a strawman argument by putting in the NIST's mouth that the perimeter columns didn't fail before the 8° threshold.

Please recall the following comments by the NIST concerning an 8 degree tilt for WTC1:

The more I read it, the more evident it is to me that NIST are NOT saying that the failure occurred after the 8° tilt. The summary you posted made it pretty clear.

If you read these two points as not sequential but overlapping in time, you will see where your mistake is in understanding that part:

• 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.

To me it's pretty clear that the 8° measurement is just supporting the idea that there was a tilt.​

 

[Seymour Butz]

Since this is wrong, the answer is....... no.

http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR 1-2.pdf

p. 101 or 215/462

States that, "Core perimeter beams were joined with splice plates in the *SAME* manner as the wide flange columns described above." (where they describe the core columns and their connections) and then says, "..... and was appropriate for modeling strong welded connections."

Figure 5-8 shows the details of a box column to wide flange column transition. Welded. Not bolted.

Figure 5-7 shows detail of wf to wf connections. Welded. Not bolted.

Bump.

Do you have other info?

 

[Major_Tom]

Pgimeno, sorry about the alteration in the quote. Accident. Why do you think they keep mentioning the number "8 degrees"? What is so important about that number that they keep repeating it?


Seymour. I have other info. It is very hard to find it in the NIST reports. I was never able to find out about staggered or aligned core column connections and the nature of the connections in the main reports. I always assumed they were welded just like you.

I found out that the core columns connections are all aligned at the same elevations by looking at many photos of the original construction process. At about the same time data came out about the core column cross sections and was put on this site:

http://wtcmodel.wikidot.com/nist-core-column-data

It confirmed that core column connections were aligned and that they exist on floor 89, 92, 95, 98, 101, 104 in the collapse initiation area.
>>>>>>>>>>>>>>>

What are the nature of the 98th floor core column connections? In old inspection reports they talk about inspecting core column connections in these areas. I found the information there.

There is also a photo of a core column from floors 98 to 101, WTC1 in the NIST reports. The end of that column has 2 bolted plates.

 

[Dog Town]

Why do you think they keep mentioning the number "8 degrees"? What is so important about that number that they keep repeating it?

NIST uses it where necessary! You are the one that keeps repeating it, over, and over! What you think is so important about it, is what seems so out of whack. Not the other way around.
Typical!

 

[sheeplesnshills]

Of course we at ae911truth believe that the failures conclusively prove that a
structural engineer must have pushed the plungers making sure that the buildings fell in the correct order and fell the correct way. So that they just looked like a fire failure.

OMG you really can't be this stupid.....if it looks exactly like a fire (and impact) induced failure and there is zero evidence that it was anything else only an insane fool would think it was something else.............The Haiti Earthquake looked exactly like a normal earthquake and their is zero evidence that it was anything else so you would assume the NWO (or whomever ...........) did it.

The Titanic looked it hit an iceberg and there is no proof it didn't so the OWO (old world order) sank it?????

Bazant could be 100% wrong and it makes no difference unless you can show that there is no possible impact and fire initiation event that would have caused the collapse as seen OR that there is solid evidence of explosives being used. You are making the extraordinary claims, you have to provide the evidence to back them up.

Come back to us when you can show either of these.

 

[pgimeno]

Pgimeno, sorry about the alteration in the quote. Accident. Why do you think they keep mentioning the number "8 degrees"? What is so important about that number that they keep repeating it?

The fact that they repeat it doesn't make it important.

What's so important about, say, Bank Fuji as a tenant? Do you consider that an important detail in the collapse? Yet it is mentioned in NCSTAR 1 p.39, several times in NCSTAR 1 p.79, in NCSTAR 1 p.121, in NCSTAR 1-1C p.116, several times in NCSTAR 1-1H p.57, several times in NCSTAR 1-5 p.44... Do you think that all these mentions make the fact that the Fuji bank was a tenant, more important to NIST than the 8 degree tilt?

There are quite some repetitions along the reports. These repetitions don't speak of the importance of a single datum.

 

[femr2]

The fact that they repeat it doesn't make it important.

Rotation of at least 8 degrees to the south occurred before
the building section began to fall vertically under gravity.

Wrong.

Vertical drop began after ~1 degree rotation.