OOS Collapse Propagation Model

[Woody-]

Rotation of the upper section of WTC 1 of APPROXIMATELY 1 DEGREE to the south ocurred before all four corners of WTC 1 began to descend vertically.

Geeze this is an easy one. Two corners started moving causing the top of the tower to tilt and once it got to one degree the other two corners started moving.

 

[Major_Tom]

Among the posters in this thread, Basquearche provides one of the best examples of the combination of ignorance of the subject matter and pure appeal to authority figures.

From post #322:

You don’t understand the big picture.

1) First phase of Towers 1,2 global collapse is the damage and gradual failure of the critical floor. This initial failure is what NIST exhaustively studied and provided a gravity alone explanation.

2) Second Phase of Towers 1,2 is the progressive collapse of the remainder of the structure to grade following the initial failure of the critical floor. Bazant mathematically describes this gravity alone global progressive collapse following the initial failure of the critical floor.

These two phases are complementary and universally understood to be such by the qualified peer reviewed civil/structural engineering universe and their published studies. These engineers all agree in a gravity only explanation for both phases.

Edited by Tricky: 

Be sure to properly attribute quotes and make it clear exactly what is being quoted. If you need help using the quote boxes, check the BB Code List in the FAQ.

We have already established that NIST screwed up the angle over which the initial failures occurred.
If the building tilted over 8 degrees while the columns failed from south to north as the NIST claims, can the west wall possibly have done this?

Drop curves of the 104th floor fire and the NW corner show that all 60+ columns in the west wall failed within an interval of 0.5 seconds.

That strong, forceful row of ejections seen emerges before any point on the west face starts to move. Synchronized data shows this conclusively, but you can just use your own eyes to see it is true.

This is obviously not a south to north failure over 8 degrees and you can see it just by looking at the west wall.

There is no evidence within the NIST reports that the NIST looked closely at the collapse initiation sequence of WTC1 at all.

(This is just one application of drop curves for those questioning the value of actually measuring things accurately in the femr data analysis thread.)

 

[carlitos]

Major_Tom,

It seems that, despite your engineering prowess and vast knowledge of technical subjects, you can't quite figure out how to use the 'quote' button. It really is there so we can tell what you're quoting and who wrote it. This seems especially relevant when you link a post from like 700 posts ago. It's almost like you don't want to use standard formatting, to prove that you are a non-standard kinda guy.

Secondly, if you could find a way to learn the "spoiler" or "nsfw" tags, it would be appreciated. That way, your 3.5 meg animated gif wouldn't be slowing down my lame computer right now.

 

[9/11 Chewy Defense]

Among the posters in this thread, Basquearche provides one of the best examples of the combination of ignorance of the subject matter and pure appeal to authority figures.

From post #322:

"You don’t understand the big picture.

1) First phase of Towers 1,2 global collapse is the damage and gradual failure of the critical floor. This initial failure is what NIST exhaustively studied and provided a gravity alone explanation.

2) Second Phase of Towers 1,2 is the progressive collapse of the remainder of the structure to grade following the initial failure of the critical floor. Bazant mathematically describes this gravity alone global progressive collapse following the initial failure of the critical floor.

These two phases are complementary and universally understood to be such by the qualified peer reviewed civil/structural engineering universe and their published studies. These engineers all agree in a gravity only explanation for both phases."
Link to post http://www.internationalskeptics.com/forums/showpost.php?p=5982409&postcount=322

We have already established that NIST screwed up the angle over which the initial failures occurred.
If the building tilted over 8 degrees while the columns failed from south to north as the NIST claims, can the west wall possibly have done this?

[qimg]http://img690.imageshack.us/img690/9109/femrnew.gif[/qimg]

Drop curves of the 104th floor fire and the NW corner show that all 60+ columns in the west wall failed within an interval of 0.5 seconds.

That strong, forceful row of ejections seen emerges before any point on the west face starts to move. Synchronized data shows this conclusively, but you can just use your own eyes to see it is true.

This is obviously not a south to north failure over 8 degrees and you can see it just by looking at the west wall.

There is no evidence within the NIST reports that the NIST looked closely at the collapse initiation sequence of WTC1 at all.

(This is just one application of drop curves for those questioning the value of actually measuring things accurately in the femr data analysis thread.)

Can we agree that the buildings collapsed no matter what the angles were?

Can we also agree that NIST didn't get anything wrong & that you assume too much when knowing very little?

 

[Kent1]

Can we agree that the buildings collapsed no matter what the angles were?

Can we also agree that NIST didn't get anything wrong & that you assume too much when knowing very little?

Agreed, its clear Major Tom hasn't read the report closely, or this thread.
Either english isn't his first language or his elevator doesn't reach the top floor.

 

[pgimeno]

We have already established that NIST screwed up the angle over which the initial failures occurred.

Wrong. We have already established that NIST's wording was confusing, because they knew that the 8 degree tilt was the angle at which the dust obscured the view, as shown in figure 6-11 of NCSTAR 1-6 p.166.

If the building tilted over 8 degrees while the columns failed from south to north as the NIST claims, can the west wall possibly have done this?

Beginning by the fact that NIST doesn't claim that, as you were shown already, it's a strawman argument.

Drop curves of the 104th floor fire and the NW corner show that all 60+ columns in the west wall failed within an interval of 0.5 seconds.

That's slower than what I would have thought, but then I suppose the top had some inertia preventing more abrupt movement.

There is no evidence within the NIST reports that the NIST looked closely at the collapse initiation sequence of WTC1 at all.

Have you read them at all?

(from NCSTAR 1-6 p. 156)

 

[Major_Tom]

Pgimeno, there is no dust obscuring the failure of the NW corner, the last section to fail. I can locate the event to within a fraction of one second.

A condensed but thorough summary of how the NIST explain the initial sequence of buckling which led to collapse of WTC1 is in NCSTAR 1-6D, Ch 5, section 5.2, p312 to 318 (draft form from p305 to 312), in a section titled "WTC 1 Collapse Sequence" and 1-6draft 9.3.1, p 287-295 in a section titled "Probable collapse sequence of WTC1". Relevant sections are reproduced below.
...................

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.

Do any of you have anything else to add or were you just bluffing?

 

[Major_Tom]

The angles at the moment of the failure of the NW corner can be determined correctly, but to do it someone has to get up off their knees and do their own work.

A few independent researchers I know have already done it. The NIST did not and apparently nobody posting here did either.

In fact, their descriptions of WTC1 collapse initiation above are basically a signed confession that they gave almost no attention to it at all.

 

[Kent1]

He wasn't bluffing. Try reading what you just quoted on your last line of 1-6draft, p 317:.
"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."

Are you a native english speaking/reading person? You clearly didn't read what has been posted by us, NIST, or even yourself.

 

[Major_Tom]

This is the last group of elements to break during the collapse initiation sequence. They are not covered by dust and you can locate the moment it happens. The pictures above are low res. So use a high res version of the same images and it's not too hard.

That is the moment you want to measure angles.

That is the end of the initial failure sequence, not the BS you read in the NIST quotes.

 

[Kent1]

If you want to measure that, go ahead.
But with regards to the 8 degrees that keeps coming up (like post #1082), it's a different story that NIST did not get incorrect.

 

[Major_Tom]

WHy don't you read all the quotes, Kent, not just the one you like.

 

[Kent1]

WHy don't you read all the quotes, Kent, not just the one you like.

I have, now try reading this thread where it was already discussed and resolved. Start at post 1039.

 

[pgimeno]

Pgimeno, there is no dust obscuring the failure of the NW corner, the last section to fail. I can locate the event to within a fraction of one second.

So what? The 8 degree tilt happened well after the initiation, as evidenced by these photos:

I have measured about 8° from the last photograph.

Do any of you have anything else to add or were you just bluffing?

Bluffing? I have shown you how another engineer interpreted NIST in a paper, therefore showing your incompetence when it comes to interpret NIST's words:

For the North Tower, it was assumed in the calculations that the tilt in the south direction varied during the first 5 s from 2.8° to 8° [which is the angle reported by NIST (2005)], and that it was zero in the east direction.​

(from [BLGB], p.901). Any clue of that being before the collapse started? No? Well.

 

[Reactor drone]

http://www.sharpprintinginc.com/911/images/pagemaster/nw_corner1.5_web.jpg
http://www.sharpprintinginc.com/911/images/pagemaster/nw_piece_web.jpg
http://www.sharpprintinginc.com/911/images/pagemaster/nw_piece_web_zoom.jpg

This is the last group of elements to break during the collapse initiation sequence. They are not covered by dust and you can locate the moment it happens. The pictures above are low res. So use a high res version of the same images and it's not too hard.

That is the moment you want to measure angles.

That is the end of the initial failure sequence, not the BS you read in the NIST quotes.

Since I had a little time on my hands today I decided to have a look at the western view of the WTC1 collapse that NIST used. I aligned the screen captures in photoshop and marked reference points at the NW top of the building, base of the antenna and top of the antenna. the first significant drop occurred in the fourth frame.

At that point I measured the angle at 7.8° which corresponds quite well with NISTs 8° figure.

Since Major Tom has given a photo showing his final release point I thought I'd see if I could find a corresponding view from the west.

In Major Tom's release point there is a significant eruption of flame from the northern windows of the building which corresponds to a point after the 7.8° initial drop. If Major Tom believes the antenna angle in his shot is less than 1° I think he needs to redo his calculations.

 

[Major_Tom]

That is obviously not the release point. You cannot see that by yourself?

The release point is identified by drop curves, not by using your eyes. Please watch what femr is doing in the thread on his data analysis.

You trace building features and analyze the drop data to discover release points correctly.

Eyeballing it is rather primitive as you have just shown.

The NIST has also show that guessing and eyeballing data is very, very primitive, as seen in their scant and incorrect description of the initiation sequence.

 

[Major_Tom]

Let's review how to identify release points from drop curves:

If we want to know how WTC1 moves during collapse initiation we need to measure it. It is not possible to measure it without tracing points on the building and studying drop data.

We will be looking at many drop curves so we need to know what features to look for. This is one method I use. Maybe it will help you, too?

ONE APPROACH TO READING DROP CURVES


First, locate the release event. In some frame the velocity will begin to take off, meaning the slope of the velocity plot changes quickly. This is because there is an abrupt change in acceleration. This frame can be called the "release event" or "release moment".

Second, separate the curve into 3 regions: A pre-release region, a post-release region and the region of the release event.

Pre-release motion could be drift, creep. deformation, tilting, vibration or any slower movement which lacks a downward acceleration at a significant percent of g. A careful researcher should trace points in the pre-release region as far back as necessary to discover the earliest motion possible.

Post-release motion has an average downward acceleration of 0.5g to 1.0g. It may have moments of velocity reductions or may not. If so, the momentary downward acceleration between reductions may differ from the average acceleration and should be considered separately. Locations and magnitudes of the velocity reductions may provide valuable information about what is really happening inside the building over the first 12 feet of falling.

The release event Using the velocity graph, curvature at the release point may help determine how quickly the initial failure occurred.

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

Two examples

The Sauret drop curve of NW corner is shown in blue. It's corresponding velocity curve is shown in purple. We see there is an abrupt change in the slope of the velocity curve that can be traced back to frame 222. This is the release event for the NW corner.

The acceleration (slope of the velocity curve) quickly changes through frame 222. The traced point is now falling at 0.5g to 1.0g. There is one measured velocity reduction around frame 250. In frame 250 the positional data shows the NW corner has fallen about 3 ft.

In the pre-release region we can carefully study changes in the positional data as far ahead of frame 222 as we wish, looking for the earliest detectable deformations.

The Sauret drop curve of the black-white transition point on the antenna is in yellow. It's corresponding velocity curve is in light green. We see movement from frame 140, yet the velocity curve does not take off with a 0.5g to 1.0g acceleration until frame 215. The release event is around frame 215.

In the pre-release region we see considerable movement before frame 215. Over 2 feet of downward displacement is measure in the antenna between frames 130 and 215.

In the post-release region we detect one velocity reduction. How far has the traced point dropped when the reduction occurs? It happens around frame 228, when the positional data shows a 3 ft drop.

 

[Major_Tom]

We'll get to the angles soon, but first let's look at tracking data of 3 corners of the building.

Measuring the release points of 3 points along the WTC1 perimeter: the SW corner, NW corner and NE corner:


The Sauret video has the NE and NW corners tracked and plotted. 59.97 frames per second. Courtesy of Achimspok:

The velocities of the corners are included in the graph. As I mentioned earlier, probably the best way to locate a release point is to look at the positional and velocity data together. The release point is when there is a drastic change in the velocity slope. We can see that the release point for the NE corner is about frame 208 and for the NW corner it is about frame 222.

There is only about 14 frames between the NE and NW corner release points. That is less than 0.3 seconds.

(source video:

achimspok Sauret version: starts some seconds prior to the shaking camera.

File specs:
97.730.578 bytes
Audio: Dolby AC3 48000Hz 6ch 224Kbps [AC-3]
Video: MPEG2 Video 720x480 (16:9) 29.97fps 9608Kbps [Video]
duration: 02:04,124

Video fields unfolded into frames to get 7440 frames at 59.94fps. Only a segment is used. Frame 2005 of the unfolded version is the first frame "000".

Here is a link to the original file:
http://www.megaupload.com/?d=E6WOP2QS)
>>>>>>>>>>>>>>>>>>>>>>>>

Next, the SW corner 104th floor fire and the NW corners are tracked and plotted using the NBC NW viewpoint, courtesy of femr:

Measurement of the large antenna, SW corner fire and NW corner washer drops from the NW NBC viewpoint

(notes: Black - Antenna
Red - Washer
Purple - SW Fire

59.94 fps - Resolution Doubled. 1 pixel on the graph is 0.5 pixels on the original video.)

NW NBC viewpoint original file:
http://www.megaupload.com/?d=VABQMPWG
.................................

Using this drop data fro the first time in 911 research we can see that the SW corner of the west perimeter wall was released within 0.5 seconds of the NW corner.


So roughly from the data we can determine that when the 3 corners are compared........

The SW corner was released first
The NE corner was released about 0.2 seconds later
The NW corner was released about 0.3 seconds after that.


If 3 of the 4 corners of the building are released within a 0.5 second interval, it is absolutely absurd to talk about a "hinge".

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

There is no tilting mechanism I could imagine that can allow 3 of the 4 corners to be released within a 0.5 second interval. Achimspok would disagree with my 0.5 second interval and place the time interval over which 3 of the 4 corners of the building were released at a tiny 0.25 seconds as the data shows.

 

[ozeco41]

Can anyone explain to me in a couple of brief sentences what all this recent overload of technical claims and counter claims is about?

The topic is "OOS Collapse Propagation Model" which refers to the stage commonly called the "global collapse". I happen to agree in broad outline with the "OOS" concept - I published my version late 2007 early 2008 on another forum. (And, for the record, there may be aspects of Major_Tom's version where I do not agree.)

But we are now debating the "initial collapse" NOT the topic of this thread which is about "global collapse" and the specific model labelled "OOS".

Why?

The big question about the initial collapse is surely "demolition assistance or not?" and nobody with half a brain in 2010 would be supporting demolition.

So what is this discussion about? Some detailed explanation of the initial collapse? Some attempt to prove NIST wrong on minor details? There is no reasonable doubt NIST got the big issue right - no demolition. So are we trying to show that they got the right answer for the wrong reasons? If so I comprehend the purpose.

I see lots of "debate" but no-one saying where they are heading OR why they are heading that way.

 

[Reactor drone]

That is obviously not the release point. You cannot see that by yourself?

Then why did you say that it was?

This is the last group of elements to break during the collapse initiation sequence. They are not covered by dust and you can locate the moment it happens. The pictures above are low res. So use a high res version of the same images and it's not too hard.

That is the moment you want to measure angles.
That is the end of the initial failure sequence, not the BS you read in the NIST quotes.