Posted on 09/13/2006 11:37:56 AM PDT by aculeus
At the Hyatt Regency OHare near Chicago, a crowd of approximately 400 people has gathered on a pleasant summer evening. Some are old and some are young; some are dressed in colorful tie-died shirts while others wear dress shirts and slacks, but most seem cheerful and friendly. We are all waiting for the opening of the main lecture hall for the evenings event, the first of many scheduled talks during a weekend-long conference. We bide some time by looking at the items for sale: DVD copies of Michael Moores Fahrenheit 9/11, the anti-Karl Rove documentary Bushs Brain, and the more recent Walmart: The High Cost of Low Price.
There is nothing especially unusual here, since all of these are available at the Borders or Best Buy near you. But then as the doors to the main hall are about to open, one anxious attendee tries to start a chant of 9/11 was an Inside Job. A few people join in before another attendee tells him, quite emphatically, we already know! The weekend conference is the Chicago meeting for 911truth.org, one of the most visible organizations within a larger coalition known as the 9/11 Truth Movement, and most of the crowd believes that the United States government planned and orchestrated the terrorist attacks of September 11, 2001.
The statement we already know! well summarizes the attitude of the conference attendees toward the material presented during the lectures. Many at the conference do not seem to be looking for new information that might lead to more accurate perspectives about the events of 9/11. A fellow sitting near me admits, We already know this stuff; were here to reconfirm what we already know. The conference is a way for attendees to consolidate their group identity, and try to bring their message to those people at home and abroad who believe the official story of 9/11. As someone who does not share the views of the 9/11 Truth Movement, I have another objective. I want to listen to their arguments and view their evidence, and understand the reasons why so many likable and otherwise intelligent people are convinced that the United States government planned the murder of nearly 3,000 of its own citizens.
The Collapse of World Trade Center Buildings 1 & 2
When most of us recall the events of 9/11, we think of the image of those two seemingly indestructible World Trade Center towers crumbling to the ground. Not surprisingly, their collapse is also a central issue for the 9/11 Truth Movement. An overwhelming amount of the organizations talks and publicity materials address the fall of Buildings 1 and 2. But as these materials show, 911truth.org does not believe the official story that the primary damage to the WTC occurred when two airplanes hijacked by terrorists crashed into the towers. Rather, they maintain that the towers fell due to a controlled demolition, planned in advance by the United States government.
Why do they think this? A primary reason seems to be that the collapse of the towers looks like the result of a controlled demolition. Since there is no structural resistance to gravity in a controlled demolition, the building collapses straight into its own footprint, with each floor pancaking onto the floors below at or near the speed of a free fall. Many of the presenters at the Hyatt Conference compared videos of the collapse of the towers with videos of known controlled demolitions, noting the similarity in both the appearance and speed of collapse. 911truth.org maintains that if actually hit by an airplane, the steel structure of the WTC buildings should have provided at least some resistance to the weight of the floors above, causing the falling structure to pitch over to one side rather than pancake straight down. They further argue that fires caused by burning jet fuel from the crashed planes could not have caused the collapse, since jet fuel burns at a temperature of no more than 1500° Fahrenheit,1 while a temperature of approximately 2800° is needed to melt steel. David Heller makes the point in a widely read article:
The official story maintains that fires weakened the buildings. Jet fuel supposedly burned so hot it began to melt the steel columns supporting the towers. But steel-framed skyscrapers have never collapsed from fire, since theyre built from steel that doesnt melt below 2750° Fahrenheit. No fuel, not even jet fuel, which is really just refined kerosene, will burn hotter than 1500° Fahrenheit.2
Since burning jet fuel is not hot enough by itself to melt steel, reports that melted steel was observed at Ground Zero suggest to conspiracy theorists that some other incendiary substance must have been introduced.
Finally, many of the leaders of the movement claim that demolition squibs can be seen in videos of the WTC collapse just before and during the time the towers began to fall. In professional demolition lingo, a squib is an explosive device used to weaken building structure during a controlled demolition. Several presenters at the conference pointed out small bursts of debris spraying out horizontally from the towers during collapse, and identified these as squibs secretly detonated to fell the buildings.
What can we make of these allegations? First, lets examine the similarity in appearance between the collapse of the World Trade Center towers and the collapse of buildings destroyed through planned demolitions. In controlled demolitions, detonating devices weaken or disrupt all major support points in a building at the same time. Therefore, once the collapse begins, all parts of the building are simultaneously in motion, free-falling to the ground. However, this is definitely not what happens during the collapse of WTC Buildings 1 and 2. Carefully review footage of the collapses, and you will find that the parts of the buildings above the plane impact points begin falling first, while the lower parts of the buildings are initially stationary.3 The parts of the towers below the impact point do not begin to fall until the higher floors have collapsed onto them. This is not what we would expect if the towers collapsed from a controlled demolition, but it is exactly what we would expect if the building collapse resulted from damage sustained by the impact of the planes and subsequent fire damage. A conspiracy theorist may counter that the buildings were rigged to begin falling from the top down, but what are the chances that those planning such a complicated demolition would be able to predict the exact location the planes would impact the towers, and prepare the towers to begin falling precisely there?
[go to site for remainder]
It would have been fun to put on an Elvis suit and attend...
Lets advance the "massive alien abduction" theory.
Can the Congress demand for a resignation in the Administration? He was confirmed, how can the Congressional Branch tell the Administration Brach who to fire? I thought the Liberals believed in three coequal branches of Government - I hear them preaching that every chance they get.
BUMP FOR LATER READ
Murtha clearly has no idea what separation of powers means. That, or in his delusional mind, he is the President.
Try explaining to someone that you can replicate the "squibs" on your own at home without explosives. Find a dusty area outside, and drop a two foot by two foot piece of plywood on it. You'll see the dust flying out from the side as the board compresses the air under it before it impacts. I guess that makes me a government shill. I want my check from Rove!
For startes, it wasn't necessary to "melt" the steel in the WTC. The jet fuel fire was more than sufficient to heat the steel until it lost structural integrity, and soften the steel, and that is part of what led to the collapse. The collapses may well resemble other buildings that collapsed from controlled demolitions, but nobody anywhere has presented any kind of proof of these allegations what so ever.
Every time a major diaster happens there is always someone who pops up with some wild explanation of what happened. Remember the women who testified before Congress that they saw and heard the demolition charges go off that breached the levees in NO?? Same gig.
This group is just another collection of Fruit Bats looking for thier 15 minutes in the spotlight. The fact that they get any press coverage at all is proof of what a slow news cycle looks like...
Wonder why if there were controlled demolitions there was no sign of explosive charges that would create a pancake effect.
Maybe it was Roves secret explosives, created in the Texas bunker that are designed not to give off any smoke or noise.
Then again, a latticetype structure, where the outside beams support the floors would pancake. Heat expands which would expand the steel and the floor in the center would basiclly come off its hinges and fall. One falls on the other and other and other and the outside structure falls on top, creating a pancake effect.
This is only my opinion as I am neither a structural engineer or a Grucci.
The more the left buys into conspiricy theorys the better. Just makes it easier to demonstrate what nuts they are. Alienating even more voters.
I've been a weldor since the nineteen-sixties, and I can tell you that ( even ignoring the mechanical damage to supports ) ordinary structural steel starts losing its strength as it is heated up. A few hundred degrees will start the changes, to say nothing of a thousand or more degrees of fuel-stoked, wind-driven fires.
The flanges holding one floor failed, and it triphammered the rest down to the ground. That is all it took.
Uprotected steel loses about 50% of it's strength after 20 minutes of a 583C (or 1081F) fire. That's below the average temperature of a bad office fire, which is in the 650C range. NIST reported maximum air temperatures at the WTC of 1000C.
At 1000C steel does not melt, but it's effective stength is reduced to 10% of its nominal strength and the steel will deform plastically.
Yhe other lie is the building free fell in 9 seconds. Clearly portions of the building took longer to fall. I witnessed myself the interior core of the South Tower standing for approx 10 seconds longer than the rest of the building.
A fairly large number of people in any country cleave to demonstrably and manifestly false and irrational ideas at any moment.
What politician will risk insulting people who believe in alien abductions, let alone UFOs. Actually, alien abduction makes less sense (to me) than "911 was an inside job."
No politician was ever successful, who spurned the votes of the irrational and deluded.
Actually what happened is this.
the initial crash destroyed a small percentage of exterior tube columns. The exterior tubes are for resisting wind loads. The interior core was heavily damaged in both buildings, the South tower losing about 1/4 of its core columns. the impact also destroyed many floor decks that served two important purposes. They held up the floor, but more importantly laterally braced the perimeter tube.
To explain, take two pens or pencils and stand them vertically on top of each other on a desk. with one hand hold the top pencil and the other hold between both pencils. As long as you hold both pencils from moving sideways, you can push down and support a bit of weight. If you remove your fingers, the pencils quickly willpush outwards and collapse.
When the floor trusses/decking was destroyed, the perimeter tubes already overstressed, wre actually pulled inwards by the collapsed floor decks. as fires raged, damaged decking w/ blown off insulation becan to sag further. Eventually the area of the building above the damaged areas began to collapse. Each building collapsed differently.
http://wtc.nist.gov/pubs/NCSTAR1-6ExecutiveSummary.pdf
Not always. Many times they're precicely timed in sequence to influence the direction of the collapse.
NIST NCSTAR 1-6, WTC Investigation lxvii
Figure E11. WTC 1 probable collapse sequence.
1. Aircraft Impact Damage
Aircraft impact severed a number of exterior columns on the north wall from floors 93 to 98,
and the wall section above the impact zone moved downward.
After breaching the buildings exterior, the aircraft continued to penetrate into the building,
severing floor framing and core columns at the north side of the core. Core columns were also
damaged toward the center of the core and, to a limited extent on the south side of the core.
Fireproofing was damaged from the impact area to the south exterior wall, primarily through
the center of WTC 1 and at least over a third to a half of the core width.
Aircraft impact severed a single exterior panel at the center of the south wall between floors 94
and 96.
The impact damage to the exterior walls and to the core resulted in redistribution of severed
column loads, mostly to the columns adjacent to the impact zones. The hat truss resisted the
downward movement of the north wall, and rotated about the east-west axis.
As a result of the aircraft impact damage, the north and south walls each carried about 7 percent
less gravity loads after impact, and the east and west walls each carried about 7 percent more
loads. The core carried about 1 percent more gravity loads after impact.
2. Effects of Subsequent Fires and Impact Damaged Fireproofing
A. Thermal Weakening of the Core:
The undamaged core columns developed high plastic and creep strains over the duration the
building stood, since both temperatures and stresses were high in the core area. The plastic
and creep strains exceeded thermal expansion in the core columns.
The shortening of the core columns (due to plasticity and creep) was resisted by the hat
truss which unloaded the core over time and redistributed loads to exterior walls.
As a result of the thermal weakening (and subsequent to impact and prior to inward bowing
of the south wall), the north and south walls each carried about 10 percent more gravity
loads, and the east and west walls each carried about 25 percent more loads. The core
carried about 20 percent less gravity loads after thermal weakening.
B. Thermal Weakening of the Floors:
Floors 95 to 99 weakened with increasing temperatures over time on the long-span floors
and sagged. The floors sagged first and then contracted due to cooling on the north side;
fires reached the south side later, the floors sagged, and the seat connections weakened.
Floor sagging induced inward pull forces on the south wall columns.
About 20 percent of the connections to the south exterior wall on floors 97 and 98 failed
due to thermal weakening of the vertical supports.
C. Thermal Weakening of the South Wall:
South wall columns bowed inward as they were subjected to high temperatures and inward
pull forces in addition to axial loads.
Inward bowing of the south wall columns increased with time.
Executive Summary Draft for Public Comment
lxviii NIST NCSTAR 1-6, WTC Investigation
Figure E11. WTC 1 probable collapse sequence (cont).
Figure E12. WTC 2 probable collapse sequence.
1. Aircraft Impact Damage
Aircraft impact severed a number of exterior columns on the south wall from floors 78 to 84,
and the wall section above the impact zone moved downward.
After breaching the buildings exterior, the aircraft continued to penetrate into the building,
severing floor framing and core columns at the southeast corner of the core. Fireproofing was
damaged from the impact area through the east half of the core up to the north and east
exterior walls. The floor truss seat connections over about 1/4 to 1/2 of the east side of the
core were severed on floors 80 and 81 and over about 1/3 of the east exterior wall on floor 83.
Aircraft impact severed a few columns near the east corner of the north wall between floors 80
and 82.
The impact damage to the exterior walls resulted in redistribution of severed column loads,
mostly to the columns adjacent to the impact zones. The impact damage to the core columns
resulted in redistribution of severed column loads mostly to other intact core columns and the
east exterior wall. The hat truss resisted the downward movement of the south wall, and
rotated about the east-west axis.
As a result of the aircraft impact damage, the core carried 6 percent less gravity loads after
impact and the north face carried 10 percent less loads. The east face carried 24 percent more
gravity load, while the west face and the south face carried 3 percent and 2 percent more
gravity load, respectively.
After impact, the core was leaning toward the east and south exterior walls. The exterior
walls acted to restrain the core structure.
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.
Draft for Public Comment Executive Summary
3. Collapse Initiation
The inward bowing of the east wall induced column instability, which progressed rapidly
horizontally across the entire east face.
The east wall unloaded and tried to redistribute the loads via the hat truss to the weakened
core and via the spandrels to the adjacent north and south 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 east face) to the east (about 7º to 8º) and south (about
3º to 4º) as column instability progressed rapidly from the east wall along the adjacent north
and south walls. The building section above impact continued to rotate to the east as it began
to fall downward, and rotated to at least 20 to 25 degrees.
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.
2. Effects of Subsequent Fires and Impact Damaged Fireproofing
A. Thermal Weakening of the Core:
Several of the undamaged core columns near the damaged and severed core columns
developed high plastic and creep strains over the duration the building stood, since both
temperatures and stresses were high in the core area. The plastic and creep strains exceeded
thermal expansion in the core columns.
The core continued to tilt toward the east and south due to the combination of column
shortening (due to plasticity, creep, and buckling) and the failure of column splices at the hat
truss in the southeast corner.
As a result of thermal weakening (and subsequent to impact), the east wall carried about 5
percent more gravity loads and the core carried about 2 percent less loads. The other three
walls carried between 0 and 3 percent less loads.
B. Thermal Weakening of the Floors:
Floors 79 to 83 weakened with increasing temperatures over time on the long-span floors on
the east side and sagged.
Floor sagging induced inward pull forces on the east wall columns.
About an additional 1/3 of the connections to the east exterior wall on floor 83 failed due to
thermal weakening of the vertical supports.
C. Thermal weakening of the east wall:
East wall columns bowed inward as they were subjected to high temperatures and inward pull
forces in addition to axial loads.
Inward bowing of the east wall columns increased with time.
STANDARD ALLOWABLE STRESS TABLE | ||||||||||||||||||
Material | P No. | UNS No. | ALLOWABLE STRESS, ksi | MIN. YIELD STRESS, ksi | ||||||||||||||
100° | 200° | 300° | 400° | 500° | 600° | 700° | 800° | 100° | 200° | 300° | 400° | 500° | 600° | 700° | 800° | |||
SA 516-70 Carbon Steel | 1 | K02700 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 19.4 | 18.1 | 12.0 | 38.0 | 34.8 | 33.6 | 32.5 | 31.0 | 29.1 | 27.2 | 25.5 |
Type 304 Stainless Steel | 8 | S30400 | 20.0 | 20.0 | 18.9 | 18.3 | 17.5 | 16.6 | 15.8 | 15.2 | 30.0 | 25.0 | 22.4 | 20.7 | 19.4 | 18.4 | 17.6 | 16.9 |
Type 304L Stainless Steel | 8 | S30403 | 16.7 | 16.7 | 16.7 | 15.8 | 14.7 | 14.0 | 13.5 | 13.0 | 25.0 | 21.4 | 19.2 | 17.5 | 16.4 | 15.5 | 15.0 | 14.5 |
Type 309S Stainless Steel | 8 | S30908 | 20.0 | 20.0 | 20.0 | 20.0 | 19.4 | 18.8 | 18.2 | 17.7 | 30.0 | 26.3 | 24.2 | 22.7 | 21.6 | 20.8 | 20.32 | 19.7 |
Type 310 Stainless Steel | 8 | S31008 | 20.0 | 20.0 | 20.0 | 19.9 | 19.3 | 18.5 | 17.9 | 17.4 | 30.0 | 26.5 | 24.2 | 22.6 | 21.4 | 20.6 | 19.9 | 19.4 |
Type 316 Stainless Steel | 8 | S31600 | 20.0 | 20.0 | 20.0 | 19.3 | 18.0 | 17.0 | 16.3 | 15.9 | 30.0 | 25.9 | 23.4 | 21.4 | 20.0 | 18.9 | 18.2 | 17.7 |
Type 316L Stainless Steel | 8 | S31603 | 16.7 | 16.7 | 16.7 | 15.7 | 14.8 | 14.0 | 13.5 | 12.9 | 25.0 | 21.3 | 19.0 | 17.5 | 16.4 | 15.6 | 15.0 | 14.4 |
Type 317L Stainless Steel | 8 | S31703 | 20.0 | 20.0 | 19.6 | 18.9 | 17.7 | 16.9 | 16.2 | 15.5 | 30.0 | 25.5 | 22.8 | 21.0 | 19.7 | 18.7 | 18.0 | 17.2 |
Type 347 Stainless Steel | 8 | S34700 | 20.0 | 20.0 | 18.8 | 17.8 | 17.2 | 16.9 | 16.8 | 16.8 | 30.0 | 27.6 | 25.7 | 24.0 | 22.6 | 21.5 | 20.7 | 20.3 |
Alloy 200 | 41 | N02200 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | NP | NP | 20.0 | 20.0 | 20.0 | 20.0 | 18.9 | 17.2 | --- | --- |
Alloy 201 | 41 | N02201 | 8.0 | 7.7 | 7.5 | 7.5 | 7.5 | 7.5 | 7.4 | 7.2 | 12.0 | 11.5 | 11.3 | 11.2 | 11.2 | 11.2 | 11.1 | 10.8 |
Alloy 400 | 42 | N04400 | 18.7 | 16.4 | 15.2 | 14.7 | 14.7 | 14.7 | 14.6 | 14.3 | 28.0 | 24.5 | 22.8 | 22.1 | 22.0 | 22.0 | 21.9 | 21.4 |
Alloy 600 | 43 | N06600 | 22.9 | 22.9 | 22.9 | 22.9 | 22.9 | 22.9 | 22.9 | 22.9 | 35.0 | 32.0 | 31.2 | 30.7 | 30.3 | 29.9 | 29.4 | 28.7 |
Alloy 625 | 43 | N06625 | 34.3 | 34.3 | 34.3 | 33.6 | 32.9 | 32.4 | 31.8 | 31.2 | 55.0 | 53.0 | 51.4 | 49.9 | 48.5 | 47.2 | 46.1 | 45.2 |
C-22(c) Alloy | 44 | N06022 | 28.6 | 28.6 | 28.2 | 27.2 | 26.5 | 26.0 | 25.6 | 25.3 | 45.0 | 40.1 | 36.9 | 34.3 | 32.2 | 30.6 | 29.4 | 28.6 |
Alloy C-276 | 44 | N10276 | 27.3 | 27.3 | 27.3 | 27.3 | 26.9 | 25.2 | 24.0 | 23.1 | 41.0 | 37.3 | 34.5 | 32.0 | 29.8 | 28.0 | 26.7 | 25.7 |
B-3(c) Alloy | 44 | N10665 | 31.4 | 31.4 | 31.4 | 31.4 | 31.4 | 31.2 | 30.9 | 30.6 | 51.0 | 47.9 | 45.4 | 43.4 | 41.9 | 40.8 | 39.8 | 38.7 |
Alloy 20 | 45 | N08020 | 22.9 | 22.9 | 22.6 | 22.2 | 22.1 | 22.1 | 21.9 | 21.8 | 35.0 | 30.9 | 29.6 | 28.4 | 27.3 | 26.5 | 26.0 | 25.2 |
Alloy 800 | 45 | N08800 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 30.0 | 27.7 | 26.6 | 25.8 | 25.1 | 24.5 | 23.8 | 23.2 |
Alloy 825 | 45 | N08825 | 23.3 | 23.3 | 23.3 | 23.3 | 23.3 | 23.3 | 23.3 | 23.0 | 35.0 | 32.1 | 30.5 | 29.1 | 27.8 | 26.7 | 26.0 | 25.6 |
AL-6XN(c) Alloy 3/16" to 3/4" | 45 | N08367 | 27.1 | 27.1 | 25.7 | 24.6 | 23.8 | 23.3 | 22.9 | 22.6 | 45.0 | 39.3 | 35.7 | 32.9 | 30.8 | 29.1 | 27.9 | 27.0 |
Alloy 904L | 45 | N08904 | 20.3 | 16.7 | 15.1 | 13.8 | 12.7 | 11.9 | 11.4 | NP | 31.0 | 25.1 | 22.7 | 20.8 | 19.0 | 17.8 | 17.1 | --- |
G-30(c) Alloy | 45 | N06030 | 23.3 | 23.3 | 23.3 | 22.5 | 21.9 | 21.3 | 20.5 | 19.7 | 35.0 | 30.0 | 27.5 | 25.8 | 24.6 | 23.6 | 22.8 | 21.9 |
Titanium Grade 2 | 51 | R50400 | 14.3 | 12.4 | 10.3 | 8.8 | 7.6 | 6.5 | NP | NP | 40.0 | 31.5 | 25.6 | 19.6 | 14.8 | 14.8 | --- | --- |
Zirconium 702 | 61 | R60702 | 15.7 | 13.7 | 11.2 | 9.1 | 7.4 | 6.0 | 5.2 | NP | 30.0 | 23.1 | 18.0 | 14.0 | 11.0 | 9.0 | 7.9 | --- |
NOTES: NP = Not Permitted by ASME Section VIII, Division 1 for use at this temperature. Temperatures are in degrees Fahrenheit. 1 ksi = 1000 psi Stresses listed above are the highest allowed by ASME Section VIII, Division 1 (A99 Addenda) for plate. |
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