Albert Doyle Wrote:

Tony Szamboti Wrote:The plumes come out of the 98th floor very evenly, indicating it is the 98th floor failing, not the damaged area below. See http://www.youtube.com/watch?v=y9-owhllM9k

If you compare the explosive dust jets blasting out further down the building in the other video to the plumes in this video it is clear as day that they are different. I think you know that. Any competent observer would instantly see that the dust plumes in this video are timed to the compression force of the falling tower and are simply smoke and dust clouds being forced out by the billowing effect of the collapse. If these were explosive blast jets they would be stronger like those allegedly in the lower floors and, more importantly, slightly precede the collapse. These plumes are soft and happen in synch with the collapse meaning they are caused by the collapse and did not cause the collapse. This is outright dishonesty because anyone can see the antenna starts to fall long before any plume of smoke appears meaning the timing is obviously way off for those plumes to be blast jets from charges that caused the antenna to drop. Meanwhile, you've failed to explain why these plumes are much slower in velocity if they are the same charges? I can explain why they are slower. Because the ones lower down are from the much greater forces involved with increasing collective mass as the plunging tower reaches terminal velocity. In short, the natural process fits the evidence. You, on the other hand, are left with weak answers that don't answer the majority of what has been said. You have yet to answer why, if the collapse was initiated by CD charges at the 98th floor, are there no dust jets like there allegedly are on the lower floors?

You're not answering the points.

Albert Doyle Wrote:

Albert Doyle Wrote:

Tony Szamboti Wrote:The plumes come out of the 98th floor very evenly, indicating it is the 98th floor failing, not the damaged area below. See http://www.youtube.com/watch?v=y9-owhllM9k

If you compare the explosive dust jets blasting out further down the building in the other video to the plumes in this video it is clear as day that they are different. I think you know that. Any competent observer would instantly see that the dust plumes in this video are timed to the compression force of the falling tower and are simply smoke and dust clouds being forced out by the billowing effect of the collapse. If these were explosive blast jets they would be stronger like those allegedly in the lower floors and, more importantly, slightly precede the collapse. These plumes are soft and happen in synch with the collapse meaning they are caused by the collapse and did not cause the collapse. This is outright dishonesty because anyone can see the antenna starts to fall long before any plume of smoke appears meaning the timing is obviously way off for those plumes to be blast jets from charges that caused the antenna to drop. Meanwhile, you've failed to explain why these plumes are much slower in velocity if they are the same charges? I can explain why they are slower. Because the ones lower down are from the much greater forces involved with increasing collective mass as the plunging tower reaches terminal velocity. In short, the natural process fits the evidence. You, on the other hand, are left with weak answers that don't answer the majority of what has been said. You have yet to answer why, if the collapse was initiated by CD charges at the 98th floor, are there no dust jets like there allegedly are on the lower floors?

You're not answering the points.

Tony, you didn't answer this. I'd be very interested in seeing one of the rebuttals Jan credits you over with this particular point. Please answer this directly. This is a checkmate as far as I'm concerned as long as you can't answer it.

Jeffrey Orling Wrote:

Albert Doyle Wrote:

Tony Szamboti Wrote:This is just pure nonsense.

No it's not. If the 98th floor were intact and had its frame solidly connected it would fall as one unit as the structure below it failed. This would give the illusion of the collapse starting at the 98th floor but would really be the first level that fell as one unit appearing to be the fail point. Truth is the remaining damaged area below it is what gave out and the intact 98th floor flat is what fell into it.

I've tried to make this point to Tony numerous times with no success. The columns and stucture in the 3 floors BELOW 98 all supported by columns from 4' above floor 96 to 4 feet above 98 sustained considerable impact damage as did those from 93 to 96. When this 6 story region failed the top which was little damaged came down.... see the attached slide. The outburst of debris is consistent with the damage and the structure.

Lauren Johnson Wrote:Jeffrey, As I understand your sketch entitled Top Drop Cartoon, the load supported by the compromised core columns was slowly transferred to the perimeter columns via the hat trusses. As the perimeter column exceeded their designed load capacity, they began to buckle and slip pulling the core columns down. The core detaches from the hat trusses. After that I am a little vague. But somehow this leads to a cascading collapse which Major Tom calls ROOSD, which stands for Runaway Open Office Space Destruction. Am I correct in interpreting your cartoon?

Jeffrey Orling Wrote:

Lauren Johnson Wrote:Jeffrey, As I understand your sketch entitled Top Drop Cartoon, the load supported by the compromised core columns was slowly transferred to the perimeter columns via the hat trusses. As the perimeter column exceeded their designed load capacity, they began to buckle and slip pulling the core columns down. The core detaches from the hat trusses. After that I am a little vague. But somehow this leads to a cascading collapse which Major Tom calls ROOSD, which stands for Runaway Open Office Space Destruction. Am I correct in interpreting your cartoon?

Basically you are getting the gist of the diagram. It's meant to show what happens as the core columns are weakened. When the lose capacity the 12 floors of the core ... and there were only 2 elevator chafts in the core at that height... were hanging from the hat truss. And this include part of the weight of the floors outside the core as the 24 perimeter core columns support about 45% of the outside the core floor loads. When the core lost capacity all of the loads were moved over to the facade columns which buckled and in so doing there was lateral translation and the facades slipped past each other 2 side passed outside and 2 inside. But surely the facade wasn't able to carry the floor loads alone including those inside the core up there. This mass.. became the ROOSD mass driving through the inside of the tower down to the ground.

Lauren Johnson Wrote:

Jeffrey Orling Wrote:

Lauren Johnson Wrote:Jeffrey, As I understand your sketch entitled Top Drop Cartoon, the load supported by the compromised core columns was slowly transferred to the perimeter columns via the hat trusses. As the perimeter column exceeded their designed load capacity, they began to buckle and slip pulling the core columns down. The core detaches from the hat trusses. After that I am a little vague. But somehow this leads to a cascading collapse which Major Tom calls ROOSD, which stands for Runaway Open Office Space Destruction. Am I correct in interpreting your cartoon?

Basically you are getting the gist of the diagram. It's meant to show what happens as the core columns are weakened. When the lose capacity the 12 floors of the core ... and there were only 2 elevator chafts in the core at that height... were hanging from the hat truss. And this include part of the weight of the floors outside the core as the 24 perimeter core columns support about 45% of the outside the core floor loads. When the core lost capacity all of the loads were moved over to the facade columns which buckled and in so doing there was lateral translation and the facades slipped past each other 2 side passed outside and 2 inside. But surely the facade wasn't able to carry the floor loads alone including those inside the core up there. This mass.. became the ROOSD mass driving through the inside of the tower down to the ground.

This disagrees with the NIST analysis I take it--although the details escape me? And has this thesis been discussed in the requisite journals? I gotta say that anon posters over at randi don't cut it when it gets down to it. OK, now I will stare at the diagram some more.

Quote:The hat trusses are central to the "probable collapse sequence" described by NIST's Final Report on the Twin Towers. It blames the hat truss for transferring "column instability" between the core structures and the perimeter walls. In other words, it asserts that reinforcing structures caused the Towers to self-destruct. Its section entitled "Results of Global Analysis" describes the "structural deterioration" of the North Tower as follows:[TABLE="class: figure_right, width: 270, align: right"]
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[TD]This schematic from Chapter 2 of the FEMA Report provides some detail on the geometry of the hat truss.[/TD]
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6.14.2 Results of Global Analysis of WTC 1

After the aircraft impact, gravity loads that were previously carried by severed columns were redistributed to other columns. The north wall lost about 7 percent of its loads after impact. Most of the load was transferred by the hat truss, and the rest was redistributed to the adjacent exterior walls by spandrels. Due to the impact damage and the tilting of the building to the north after impact, the south wall also lost gravity load, and about 7 percent was transferred by the hat truss. As a result, the east and west walls and the core gained the redistributed loads through the hat truss.

Structural steel expands when heated. In the early stages of the fire, structural temperatures in the core rose, and the resulting thermal expansion of the core was greater than the thermal expansion of the (cooler) exterior walls. About 20 min. after the aircraft impact, the difference in the thermal expansion between the core and exterior walls, which was resisted by the hat truss, caused the core column loads to increase. As the fires continued to heat the core areas without insulation, the columns were thermally weakened and shortened and began to transfer their loads to the exterior walls through the hat truss until the south wall started to bow inward. At about 100 min, approximately 20 percent of the core loads were transferred by the hat truss to the exterior walls due to thermal weakening of the core; the north and south walls each gained about 10 percent more loads, and the east and west walls each gained about 25 percent higher loads. Since the hat truss outriggers to the east and west walls were stiffer than the outriggers to the north and south walls, they transferred more loads to the east and west exterior walls.

The inward bowing of the south wall caused failure of exterior column splices and spandrels, and these columns became unstable. The instability spread horizontally across the entire south face. The south wall, now unable to bear its gravity loads, redistributed these loads to the thermally weakened core through the hat truss and to the east and west walls through the spandrels. The building section above the impact zone began tilting to the south as the columns on the east and west walls rapidly became unable to carry the increased loads. This further increased the gravity loads on the core columns. Once the upper building section began to move downwards, the weakened structure in the impact and fire zone was not able to absorb the tremendous energy of the falling building section and global collapse ensued.
[SUP]1 [/SUP]
[emphasis added]
[TABLE="class: figure_center, width: 600, align: center"]
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[TD]This illustration from Page 11 of NIS[/TD]
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http://911research.wtc7.net/wtc/arch/hattruss.html