Guys,
This will be my last response to Heiwa's nonsense. I've decided to make it simple, but comprehensive.
Please forgive the amount of "stating the obvious" at the beginning. The folks that have had trouble understanding Heiwa's nonsense are those who have difficulty with fundamental physics.
Heiwa's objections seem to be based on two assertions:
1. That, once components of the upper Part C have been wrenched from their connections and turned into rubble, they lose their ability to destroy components in the lower Part A.
2. The upper portion of the tower (Part C) should have been destroyed during the crush down in approximately equal measure to the number of floors below that were destroyed. So that if the upper block consisted of approximately 12 stories (F99 - F110), then it should have been "eroded" by the time it crushed the lower block down about 12 - 15 stories. And the crush down should have therefore stopped around the 70th - 80th floor.
(I'll ignore the bit of inanity that "the upper block should have bounced" completely.)
Both of these assertions are completely wrong.
Here's why.
1. Fundamental Physics
The first assertion seems to have some justification in common sense. Most of us would prefer to have 5 pounds of loose bolts dropped 5' on top of our head than a 5 pound block of steel. Yet, aren't the bolts just a "broken up" 5 pound block of steel?
The answer to this is pretty easy. It lies in the fact that all damages that are caused by collisions are due to "inertial forces".
When we are hit with 5 lbs of loose bolts, the only masses that we have to accelerate (i.e., bring to a near stop from their velocity) are the individual bolts that are actually in contact with us. The fact that the bolts themselves are not connected to each other means that most of the bolts are not in contact with us at any given instant, and are not contributing to the forces applied to us. The collisions are, in essence, spread out in time.
In the case of a steel block, the internal atomic connections between all the parts of the block means that there is only one collision that happens all at once. And the entire mass of the rock needs to be accelerated. And the force that it applies to our head is much greater.
But let's look at an intermediate case. All the bolts are gathered in a steel mesh. If the mesh is very elastic, it approximates the separate bolts. If the mesh is stiff, then it approximate the solid block.
It is going to turn out that in the collapse of the towers, the mesh was made from the rebar in the concrete and the cross bracing. This mesh that is going to sweep up & trap the majority of the debris created by the crush and tie it all together at the bottom of the descending Part C of the towers.
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2. The errors in Heiwa's model:
It is pointless to attempt to draw correct conclusions from incompetent models. Models must be tied to physical reality. Many folks have already pointed out several of his flaws in both his model & his analysis.
Heiwa's "Part A/Part C" model is incompetent. He has defined Part A & Part C as "the lower & upper portions (respectively) of the building that has stood for 30 years". In other words, the undamaged, as-built floors of the towers. I will accept, & hold him to, those definitions.
The specific model errors are:
1. The impact zone has suffered massive physical and thermal damage, and can NOT be included in either Part A or Part C, but needs its own descriptor (hereafter referred to as Part D).
2. Specifically, Heiwa incorrectly includes this damaged zone into his upper component, Part C.
3. When he cuts his model into a lower Part A and upper Part C, he incorrectly shows all columns stubs at the cut to be equal length and laterally braced. In reality, the column stubs are vertically staggered and have lost most of their lateral bracing.
4. He ignores the upper & lower 2-story transition zones between the crush zone and the undamaged areas. Understanding the events, and especially the asymmetries, in these two areas is crucial to understanding why the collapse progresses to the ground.
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3. The Errors in Heiwa's analysis:
These are too numerous to count. And have been detailed by numerous folks here already.
But the crucial one pertinent to this discussion include:
1. He ignores the difference between static & dynamic loads.
2. He ignores the asymmetric consequences of gravity and the vertical motion of the upper Part C.
3. He incorrectly claims that mass & energy of the upper block lose their ability to cause damage once they have broken into rubble.
4. Most important error: he ignores the fact that Part C is going to gather most of the debris created until its entire lower surface constitutes a near solid mass of impacted debris that easily crushes each Part A floor, one by one.
5. This lower solid mass of debris is also the material that protects the upper Part C from being eroded by the stub ends of Part A's columns.
As will be shown below, the direct consequence of using a competent model and analysis is that Part C never gets closer than about 10 (collapsed) stories to Part A at any time during the collapse.
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4. A Competent Model
Let's start with the basics.
Before the collapse began, there were eight floors (92 thru 99, inclusive, for 1WTC) that had suffered severe physical and thermal damage. [See NIST NCSTAR1-6, Chap 5. For physical damage, see Fig 5-1 & Table 5-1. For thermal damage, see Fig 5-13 & 5-14.]
Since this zone resembled neither of the other two parts, it requires its own description, Part D.
Therefore, before the collapse began:
Part A extends from the floors 1 thru 91.
Part D extends from the floors 92 thru 99.
Part C extends from floors 100 thru 110.
Figure 1: The Precollapse Model
Notes on the drawings:
1. All components are drawn to scale.
2. NOTE WELL: the SHORT HEAVY LINES that indicate vertical & horizontal joints between column assemblies. These are the weak points where these assemblies will fracture.
3. The cross braces have not been included for clarity.
4. The cement floors are 5" thick (4" solid, with a 1.5" wedge at the bottom that fit into the floor deck). See NIST NCSTAR1-1A, Fig 5-8, and Fig 5-9. These are drawn to scale here & one can see that the cement floors were WAFERS...!! They were amazingly thin.
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5. The collapse initiation
Figure 2: Collapse Initiation
I know that this is a hugely simplified version of the collapse and that the real event was far more chaotic than I'm presenting it. However, I believe that it illuminates the SPECIFIC phenomena that undermine Heiwa's nonsense. Most specifically, the question of "why Part C is not destroyed during the collapse".
The collapse began when the column-to-crosstruss connectors gave way on the 98th floor. The peripheral columns, that were bowed inward up to that moment, suddenly snapped. The inward bowed peripheral columns snapped thru center and outward, and the upper block immediately began to descend. [See NIST NCSTAR1-6, Sec 9-3-1 & Table 9-5.]
Figure 2 above shows the consequence of removing one row of peripheral columns. Note that the drawing shows the column assemblies removed as 3 story units, AS HAPPENED on 9/11. It is easy to see that the column damage extended above & below this floor due to the 3 story height of the column assemblies. The drawing shows Floor 98 turned into a crosshatched ellipse.
After the collapse began, there are two additional 2-story "transition zones" that appear above & below the actual crush floors. The upper transition zones are marked "Tu1" & "Tu2", for 1 story & 2 stories above the collapse zone, respectively. The lower transition zones are similarly marked "Td1" & "Td2".
Note that in zones Tu1 & Td1, 2/3rds of the columns and cross-trusses, plus all of the lateral bracing on the floor have been destroyed. Similarly, in Tu2 & Td2, 1/3rd of the columns and cross-trusses, plus 2/3rds of the lateral bracings have been destroyed.
This damage in the transition zones dramatically weakens the structural integrity of these zones that are above & below to the crush floor. We will see shortly that, while the upper transition zone fills with debris (and is thereby strengthened), the lower transition zone remains free of debris and massively weaker than either Part A, Part C or the Upper Transition Zone throughout the collapse.
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6. The Collapse Progression.
In order to see why the collapse progression only in one direction, and why it continues to the ground, it is only necessary to follow a couple more steps. After Floor 98 blows out, turns to rubble and it and Part C begin to descend, the next (approximately) symmetric collapse occurs when the rubble of floor 98 hit floor 97. As shown by others, it is highly likely that Floor 97 will collapse immediately. But assume for a moment that it does not.
The next event occurs when Part C has descended sufficiently that its floor 99 stubs impact on floor 97 while the stubs from floor 97 impact on floor 99, with the rubble from floor 98 trapped in between. This is an approximately symmetric event, that turn floors 97 & 99 into rubble.
Fig 3. Collapse of Floors 97 & 99
UP TO this point, most events have been symmetric. The symmetry ends here.
Figure 3 shows the three floors turned to rubble. What it doesn't show is the velocity of various components. The upper Part C is now descending rapidly, and it gathers up all the debris of all three floors. This debris is caught by the mesh of rebar & cross-trusses, and embeds in the open spaces of the lower part of Part C.
The mesh is also interlaced with & tied to upper Part C's core & peripheral columns. This is crucial because, as explained before, while the concrete floors can only carry & resist loads up to their own strength & the strength of their connections, the columns can carry & resist loads equal to all the floors to which they are attached.
Notice that whenever the debris is created in the crush zone, it is created from parts that are, pre-collision, stationary. But, after just one story's collapse, the descending Part C is falling much faster than a piece of debris will begin to fall. This means that the piece of debris will get swept up in the mesh of the descending part ONLY. It will not accumulate interstitially in lower Part A.
This asymmetry then becomes the exact phenomenon that allows the smaller upper Part C to crush down the bigger lower Part A. The rubble is the key.
The fact that the rubble:
1. was created from stationary mass,
2. was swept up in the descending upper Part C,
3. was entrapped in a tough horizontal mesh of cross trusses & rebar,
4. became impacted as an almost solid mass of debris, which
5. was tied to Part C's core & peripheral columns, and
6. became an impenetrable barrier that prevented the stubs of the lower columns from destroying upper Part C
resulted in a descending upper Part C that was a rectangular tube within a tube with an essentially SOLID lower end cap.
The fact that the upper floor of the lower Part A was, at ever floor:
1. a massively weakened structure
2. that had lost 2/3rds of its vertical columns and all of its lateral supports, and
3. did NOT fill in with debris
All of these phenomena are shown in Fig 4 below.
Fig. 4. Collapse of Lower Floors
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Conclusion:
It is PRECISELY this asymmetry in collected debris that destroys Heiwa's argument that "Part C will be destroyed before Part A". This asymmetry results directly from the relative motion of the various parts due to gravity, as several people have stated for months. The asymmetry ultimately DOES result in the weight of 12 or more upper stories collapsing onto each single weakened lower story.
The total collapse was inevitable.
I hope this helps.
tom
