Photographic
evidence proves beyond a doubt that floors sagged, pulling
perimeter columns in. An event some conspiracy sites suggest
never happened.
With the fire
proofing blown off, the fire only needed as little as 600
degrees C to deform the naked truss steel. Conspiracy
theorists point to the UL tests which show the trusses
sagged but never fail to say the building should have stood. But
what conspiracy theorists don't tell you is that the test was
done with a minimum of fire proofing on
the trusses. The test was never meant to find out what
caused the truss to fail. It was testing the fire proofing
to see if it was up to code.
The
1968 New York City
building
code - the code
that the towers were intended but not required to meet
when they were built required a two-hour fire rating for
the
floor system.
Shyam
Sunder, lead investigator of the NIST WTC investigation,
explained that the four laboratory tests provide only
a means for evaluating the relative fire resistance
rating of the floor systems under standard fire
conditions and according to accepted test procedures.
Sunder cautioned, "These tests alone cannot be used
to determine the actual performance of the floor systems
in the collapse of the WTC towers. However, they are
already providing valuable insight into the role that
the floors may have played in causing the inward bowing
of the perimeter columns minutes before both buildings
collapsed."
"The
fire conditions in the towers on 9-11 were far more
extreme than those to which floor systems in standard
U.S. fire rating tests are subjected," Sunder said to a
group that gathered to watch yesterday's final test at
Underwriters Laboratories (UL) in Northbrook, Ill. "Our
investigation's final assessment of how the floor system
performed in the WTC fires also must consider factors
such as the combustible fuel load of the hijacked jets,
the extent and number of floors involved, the rate of
the fire spread across and between floors, ventilation
conditions, and the impact of the
aircraft-damaged
towers' ability to resist the fire," Sunder said
http://www.sciencedaily.com/releases/2004/08/040829130757.htm
This is more
evidence conspiracy theorists are being dishonest when they
point to these tests and suggest the building should not have
collapsed. They KNOW this because this is old news.
So the fire
expands the naked truss steel and it pushes against the
perimeter columns. At this early stage the perimeter columns
are strong enough to resist the expansion and cause the
expanding truss to sag.
Computer simulation of expanding truss pushing out on a
perimeter column and sagging
As the fires
moved on to find new sources of fuel (Desks, seats, paper,
plastic, etc..) the expanded truss cools and contracts. This
contraction happened over a period of time and over many
floors. This is a very important point, because had it only
been one floor contracting the perimeter may not have
buckled as much.
If a floor sags,
it pulls both the perimeter columns and
core columns toward the center of the floor. Because the
core columns are stronger than the perimeter, the perimeter
is the side that gets pulled in.
There are plenty
of photographs from every angle which show the slow
progression of sagging of trusses and bowing perimeter
columns. It would be impossible for the NIST or anyone else
to fabricate the photos. It was one of the most photographed
and videoed events in history. It would be easy to prove the
NIST is involved in a mass murder if they doctored photos.
Yet this is exactly what some conspiracy theorists suggest.
Other conspiracy theorists say it's an optical illusion
created by heat. But it would be impossible for this
illusion (Heat/Light
refraction)
to happen only to one side of the building even when that
side of the building cooled. Light refraction changes with
the position of the person looking at it. So no two cameras
would have shown the same degree of bowing. Here conspiracy
theorists seem to want it both ways: they want to say light
refracted due to the heat, yet they also say the fires were
almost out toward the end when the bow was greatest. They
need to have it both ways but they can't.
This illusion also happens to be where the
collapse started.
A "scholar"
says the bow was due to the core columns being cut. He
points to the movement of the north tower antenna which some
originally thought moved first. But this was not the case..
"Photographic and videographic records were reviewed to
identify structurally-related events. Where possible,
all four faces of a building were examined for a given
event or time period to provide complete understanding
of the building response. Observations from a single
vantage point can be misleading and may result in
incorrect interpretation of events. For instance,
photographic and videographic records taken from due
north of the WTC 1 collapse appeared to indicate that
the antenna was sinking into the roof (McAllister 2002).
When records from east and west vantage points were
viewed, it was apparent that the building section above
the impact area tilted to the south as the building
collapsed." (NIST 2005)
The "scholar"
is starting from a false premise and building a case around
it. Something the "scholar" suggests the NIST did.
Putting
this irony aside, the real evidence that the core did not move
over time is the fact that the other faces showed no signs
of the core moving until the collapse.
Before I
continue, it's important to distinguish between the events
of the moment of collapse and the gradual progression of
bowing of the perimeter columns. I am talking about the
gradual progression of bowing. The NIST does not disagree
with the tilting of the top sections of the towers and that
the core was a major part of that. Where the "scholar"
differs is that it was the core and not the trusses which
caused the tilt/collapse. He needs it to be the core to
explain away the bowed columns and still entertain the
thought of thermite/thermate.
If the core
tilts, pulling the columns in at the impact level in, you
would see an equal but opposite reaction from the opposite
face. If the east perimeter columns were being pulled in
because the core columns tilt, the west would show
signs of being pushed out. The top would also tilt, not just
when it collapsed but over time as the perimeter is being
pulled in. Think about it, the core is connected to all the
floors above the impact point. If the trusses were in
pristine or even merely slightly sagged condition as
suggested by this "scholar", and the core and not the
trusses pulled in the perimeter columns, then the core would
have tilted pushing out the columns on the roof level.
Why is there no sign of this happening? Because it didn't.
It's just another attempt at throwing the kitchen sink in to
explain this evidence.
Why is this
important? Because no believable scenario exists to explain
explosives or thermite creating this effect. NONE. How would
thermite/thermate bow columns over time? It simply ignites
and burns chaotically. So we're left with an effect which
looks EXACTLY like the fire sagged the trusses, then
contracted and pulled in the columns with no evidence of
thermite or a credible scenario which would explain the
drawn out event.
Here are
some scholars from England who wrote a paper for a
university which explains the bowing of the columns in
detail.
http://www.era.lib.ed.ac.uk/bitstream/1842/1216/1/WTCpaper.pdf
A
helicopter pilot saw this about 10 min before
collapse but had no way of communicating that to the
people in charge.
A bow is clearly visible
on the right hand perimeter wall as trusses sag and pull in
the perimeter columns. The photo below is NOT from the NIST report.
http://wtc.nist.gov/pubs/Media_Public_Briefing_040505_final.pdf
Start at page 36 of the above NIST briefing. You can see
photographic evidence that the building was pulled in. Not
just one floor, but across many.
Note how the sagging floors pull the outer column in. There
is enough visual evidence that the trusses were pulling the
outer columns in. If you think a bomb blew up the building,
you have to explain how a bomb pulled the walls inward well
before they fell...
Starting with the moment the plane hit, survivors said the
doors wouldn't open because the building was so out of
alignment. The impacts alone BENT THE 110 STORY BUILDINGS.
That building was made to sway. I grew up in NY and have
been to that building many times. When the wind was strong
you could feel the building sway. I can't imagine an impact
that would cause the building to sway enough to knock it out
of center. A humanly unimaginable energy. That alone should
weaken the building. Once you start to pile on the fire,
unique construction, sagging trusses, and shifted load
distribution, it's not hard to imagine enough of these
factors adding up to cause a collapse. Factors which weren't
known at the time. NIST’s computer model even took the wind
shifting into account.
"It is impressive that the World Trade Center towers held up as long as they did
after being attacked at full speed by Boeing 767 jets, because they were only
designed to withstand a crash from the largest plane at the time: the smaller,
slower Boeing 707. And according to Robertson, the 707's fuel load was not even
considered at the time. Engineers hope that answering the question of exactly
why these towers collapsed will help engineers make even safer skyscrapers in
the future. ASCE will file its final report soon, and NIST has been asked to
conduct a much broader investigation into the buildings' collapse."
http://www.pbs.org/wgbh/nova/wtc/minu-trans.html
Go to: The Towers Collapse
