The 9/11 Forum

In the last post by achimspok a good gif:



Good glimpse of a pull-in along the north face. Pull-in happens along the 81 fl spandrel.

Please verify. (the 2 fat MER spandrels are fls 75, 77. Top fat MER spandrel is 77.)

Everyone agree there is strong pull-in along the north face along the 81st fl spandrel?

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What about the famous east face pull-in? Along which spandrels do we see the first strong pull-in?



I believe it is also along the 81st spandrel, but we need to verify.

We can see the green panel fold inward. It has a rather extreme angle relative to the other visible panels, then we see it fold into the building quickly as if it has already rotated 90 degrees inward.



Of all the visible columns, the green one folds in to the extreme, then we see that black object fold over it.

In fact, every green panel does the same thing, taking on extreme angles with mathematical precision, then disappearing when the inward tilt angle is as extreme as 90 degrees.



All six green panels have the 81st fl spandrel as the highest spandrel. So the behavior of these green panels is consistent with the 81st spandrel being the lowest one that pulls-inward to an extreme degree.

The extreme angle that these panels take tells us just how far the 81st spandrel has pulled in. the movement of these panels must be directly connected to the pull-in experiences along the 81st fl spandrel.



The surviving lower sheet is clearly marked. It extends up to the 80th fl spandrel.

Imagine that the lowest spandrel to experience a sharp inward pull is the 81st. As it pulls in sharply, the lower piece breaks off and the green panels fold into the building.

It makes sense that the green panels do this because the lowest spandrel is connected to the lower sheet and the top spandrel is 81, the lowest to pull into the building.

I'd like to introduce temporary working definition the famous east wall inward bowing


IB is governed by the sharp pull-in of spandrels 81, 82 (83....)

Not just along the west face but along the north face, too.


For some reason which only St Peter may know, the east and north spandrels suddenly began to be pulled inward at a rapid rate.

This 81, 82 (83...) spandrel pull-in is what we experience as "IB".


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That is my working definition, as 81 and up spandrel pull-in.


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Having done that, I can't help but point out that core column splice/weld connections were along the 80th floor.

Looking at the quick pull-in of the 81st fl spandrel, especially since it happens quickly on the north and east walls simultaneously, it is like the corner core column 1008 fails at the weld and everything above the weld falls quickly.


We are seeing a sharp contrast between 80th spandrel behavior and 81st spandrel behavior. 80 stays relatively fixed, 81 yanks inward quickly.


Obviously, if you drop the corner column at the 80th fl weld, you would get the exact same contrast.

The earliest movement is quite incredible in that the 81 st fl spandrel pulls in so much relative to global tilt that the upper corner pulls inward and neatly tucks into the lower perimeter basket.

Once again we see a sharp contrast between th 80th spandrel, somewhat stationary, and the 81st spandrel that experiences pull in displacement so sharply that the the first movements of the 81st corner edge of the floor slab seems quite horizontal.

In the final photo notice the huge contrast between the fixed 80th spandrel and and 81st spandrel that was pulled deep within the building

Perhaps we are so accustomed to seeing the video that few notice how strange it is that the earliest movement of the upper corner is horizontal, not vertical.

When sagging floor slabs are considered, rapid simulatneous north and east sag seems absurd. Yet if only on one side, why does the corner react so quickly as to create horizontal movement before significant vertical downward movement.

The edge movement is the result of 81 spandrel pull-in on the east and north sides simultaneously. If this is done it is not hard to see why the corner must pull in also.


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Imagine you can magically make all the colored panels disappear.

Now you have 2 identical sheets, upper and lower, with a large empty gap between them.



Without those pesky colored panels, it seems pretty easy to slide the upper behind the lower, You just need to pull in and pivot the upper sheet.

Both can be achieved by dropping the east side of the core. With just empty space instead of colored panels, can the general action shown in the series of 8 photos be duplicated?

It doesn't seem hard.

The red break line in the graphics above is incorrect. The correct one is in purple below.

A better perspective:



The inward bowing during collapse initiation was witnessed as a sharp pull-in along the 81, 82 spandrels marked in green.

Also, the area around the blue line was pulled in at the same time (it is drawn on the south face but it was observed on the north face.)

The lower perimeter breaks along the purple bolted connections after the green spandrels are quickly pulled into the building.

The orange line is a row of bolted and welded column-to-columns connections running along the top of the MER panels.

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It would be easy to see what is happening if we remove the north and south walls. We could then imagine how to duplicate inward bowing, the tilting and the breaking and push-out of the lower east wall below the purple break.

Without north and south walls this doesn't seem hard. Everything would move correctly if the east side of the core begins to drop above the 80th slab.

We know that there are welded core column connections for all 47 core columns between the 80th and 81st floor slabs.


If the east CC connections above the 80th fl slab break and the east core starts to fall, it is easy to see how everything happens just as it should.

The 81st and 82nd spandrels would be quickly pulled into the building and the rest is smooth sailing.

Without north or south walls it isn't difficult to understand how to pull in the green spandrels.


The wall breaks along the purple steps and tilt begins.

Tilt could just continue until natural failure or the final release can be done intentionally at any tilt angle desired by kicking the yellow 75th fl beam slab out the back of the building with MER perimeter (red) still attached in the NW aand SW corners.




In this case from the area in the red circle the 500 row core columns can be destroyed and kick the yellow slabs in both corners out the west side of the building still attached to the 75-78 MER perimeter (red).

By using the beam flooring to transfer a destructive pulse to the MER perimeter from the red circle, all pivot points for the tilting upper section would be detroyed in a moment from a location deep within the building.

MER west perimeter and remaining 500 row core columns can be attacked at the same moment, destroying the "hinges" and allowing the whole upper portion to fall.


It is interesting because the MER west perimeter can be attacked from over 60 ft within the interior of the building.

In this case, a tilt would develop and then we'd see the 2 west corner MER sheets suddenly pop out of the building with surprising force and fall right next to one another with large sections of beam flooring still attached.


Hmmm...

The collapse initiation process of WTC2 can now be expressed as a series of 5 observed events:


1) Rapid inward pulling of the 81, 82 spandrels, results in inward bowing
2) Appearance of 78th fl ejections at the moment the upper and lower perimeter sheets separate completely.
3) Tilting
4) Appearance of row of 75th fl ejections along east face
5) Ejection of NW and SW quarter of MER panels and 75th fl beam flooring westward as top falls

then

6) The beginning of a smooth continuous ejection flow down the building


First there is a rapid inward bowing but the building cannot tilt until the east wall breaks into two separate pieces. The final snapping into 2 separate pieces happens when the 78th fl ejections become visible.

The 78th fl ejections become visible when tilting begins.

Quite a tilt forms as the top seems to deform and fall into a stiffer lower portion.

The 75th fl east row ejections appear and a few moments later the stiffened MER level west side corners are ejected from the building forcefully. Top descends.

A simple 5 stage process and all 5 events are visible.

1) Rapid inward pulling of the 81, 82 spandrels, results in inward bowing
2) Appearance of 78th fl ejections at the moment the upper and lower perimeter sheets separate completely.
3) Tilting
4) Appearance of row of 75th fl ejections along east face
5) Ejection of NW and SW quarter of MER panels and 75th fl beam flooring westward as top falls

then

6) The beginning of a smooth continuous ejection flow down the building

Rephrasing...

5 stage initiation sequence:

1) 81, 82nd fl spandrels pull in sharply............................inward bowing
2) 78th fl ejections..................................................east wall separates into upper and lower parts

this allows tilting to begin

3) Tilting

whole upper part drops with this action

4) 75th fl east face row of ejections
5) 75th fl west wall north and south quarter of MER panels ejected from building with flooring. NW and SW MER corners are destroyed.


The first 2 stages allow tilting to begin. Stages 4 and 5 finish the tilt and begin the fall.

The first 2 stages initiate tilt. The final 2 stages terminate tilt.