911 - Impossible Collapse ARCHITECTS

For Some, the Doubts Began Early

"Something is wrong with this picture,"
thought Nathan Lomba, as he watched replays
of the Twin Tower collapses on television on
September 11, 2001.

A licensed structural engineer trained in
buildings. responses to stress, Lomba saw
more on the screen than you or I. He puzzled,
"How did the structures collapse in
near*symmetrical fashion when the damage was
clearly not symmetrical?"

Lomba was hardly alone in his discomfort.
Most structural engineers were surprised when
the towers fell.

They mainly kept their misgivings to
themselves, though, as Scientific American
and the Journal of Engineering Mechanics,
BBC, the History Channel and government
agencies such as FEMA and NIST offered
varying and often imaginative theories to
explain how fires brought the towers down. In
2006, San Francisco Bay Area architect
Richard Gage, AIA, began raising technical
questions among his professional colleagues
about the destruction of the Twin Towers and
47 story WTC Building 7. Those who take time
to look at the facts overwhelmingly agree
that vital questions remain unanswered, Gage
has found. Today more than 30 structural
engineers, experts in what can and cannot
bring down buildings, have joined almost 700
other Architects & Engineers for 9/11 Truth
in signing the petition demanding a new
investigation.

They cite a variety of concerns about the
"collapses" and the inadequacies of official
reports. Many, like Lomba, find the unnatural
symmetry of all three collapses suspicious.
The rapidity of collapse . acknowledged by
the government as essentially free* fall
acceleration . was troubling, too. Some note
that the fires were weak; others ask how the
tilting upper section of WTC 2 "straightened"
itself. Everywhere you look, pieces of the
puzzle don.t fit what we.ve been told.

New evidence mounting over the years only
validated initial discomfort: eyewitness
testimony of explosions, unexplained molten
iron in the debris pile, and chemical
evidence of steel*cutting incendiaries . all
omitted from government reports. Many
engineers attack implausibilities in the
Ba.ant pile driver model, the 2002 FEMA
report and the 2005 NIST report, and also
slipshod and dishonest methodology. Finally,
the collapse of WTC 7, not hit by any
airplane, mystified others. The repeated
postponement of the government.s report
seemed to add fuel to the fire. Artificial
Symmetry The symmetry of collapse struck Paul
Mason, a structural engineer in Melbourne,
Australia, and Dennis Kollar, P.E. (licensed
Professional Engineer in Wisconsin). Kollar
was troubled by the collapses. "totality and
uniformity" and the fact that the mass of
debris remained centered on the building core
all the way down. The towers should have
fallen "with increasing eccentricity as the
collapse progressed," writes Howard
Pasternack, P.E. These systematic collapses
required that many structural connections not
only fail "nearly simultaneously," but also
"in sequential order," wrote Frank Cullinan,
P.E., who designs bridges in Northern
California. That.s "impossible from
asymmetrical impact loading and ... small,
short*duration fires."

The engineers find it difficult to believe
the government.s claim scattered fires
brought about such an orderly collapse.
Failure of heat* weakened steel would show
"large deflection, asymmetric and local
failure, and slow progress," David Scott told
colleagues at the Institution of Structural
Engineers in the UK. It.s "a gradual
process," agrees Anders Björkman, and "cannot
be simultaneous everywhere." A Swedish naval
architect working in France, Björkman
maintains that failures "will always be local
and topple the mass above in the direction of
the local collapse." William Rice, P.E., a
Vermont structural engineer, expects
fire*induced failures to be "tilting, erratic
and twisting." while Ronald Brookman, S.E., a
licensed structural engineer from Novato,
California, figures on "a partial collapse to
the side." Symmetrical collapse requires
simultaneous failure of all supporting
columns, notes Charles Pegelow. "How could
all 47 core columns fail at the same
instant?" Pegelow has performed design work
on offshore oil rigs and tall buildings. His
opinion: "Fires could not do that."

Impossible Collapse Acceleration

The National Institute of Standards and
Technology (NIST) characterized the Twin
Towers. collapse as "essentially in free
fall" (Section 6.14.4 of NIST NCSTAR 1).

Brookman wrote asking NIST investigators why
debris fell "with little or no resistance
from the intact structure below." Rice
questions how each tower "inexplicably
collapsed upon itself, crushing all 287
massive columns on each floor [while
maintaining near-freefall speed] as if the
80,000 tons of supporting structural steel
framework underneath didn.t exist." 4 Falling
objects should take "the path of least
resistance," notes Pasternack, while official
explanations claim that Tower debris took the
path of greatest resistance . through the
strong, cross* braced core structure all the
way to the ground. The Twin Towers were
overbuilt to prevent office workers from
getting seasick on windy days, says Kollar.
"There.s so much redundancy.... The building
has to be stiff enough so it doesn.t sway."
Perimeter columns designed to endure
hurricanes, Scott says, were loaded only to
"about 10% of their ultimate capacity" in the
gentle breeze on 9/11. 5 Gravity was "a
negligible part of the loading," says Kollar,
citing a claim by the Towers. engineers
Worthington, Skilling, Helle & Jackson that
even with all the columns on one side cut,
and several around the two corners, the Tower
would still withstand 100 mile*per*hour
winds. 6

The rapid breakup of this robust structure
appears to defy the laws of physics,
engineers say. Forty*five years of structural
design experience inform the view of Claude
Briscoe, P.E., that the government.s collapse
theories "seem to defy the laws of mechanics,
conservation of energy, and known structural
failure behavior." In the official story, the
kinetic energy of the falling debris would
have been largely absorbed by the energy
required to dismember the structure, bending
and twisting steel components, and
pulverizing 220 acres of concrete floors. To
accomplish all this while achieving a nearly
free*fall* speed collapse is "simply not
physically possible," says Mason. "There is
not sufficient energy available.... For this
massively strong structure to just crumble
away at near*free*fall speed would have
required immense amounts of explosive
energy." Weak Fires Vs. Explosive Events
Though four official accounts blame fire for
the destruction of all three World Trade
Center towers, the fires do not appear to
have been particularly severe. NIST states
that the jet fuel burned off in just ten
minutes. 7 "They also acknowledged that
office furniture burns for only 15 to 20
minutes in any one area" before it.s
consumed, 8 Scott points out. "There.s ample
evidence that the steel temperatures got
nowhere close to the "600+ degrees Centigrade
[1,200

degrees Fahrenheit] required to cause
failure." We saw no "raging infernos" on TV,
David Huebner, P.E., points out. Sooty smoke
and dull red flames, Scott says, indicate
"cool fires ... fuel*starved fires." Firemen
at the 78th*floor impact zone reported "only
two small fires," Scott adds, "not the 1000*
degree*Centigrade inferno" government
officials claim. New York Fire Department
(FDNY) personnel, trained to assess fires.
structural hazards, had no reason to expect
total collapse, Brookman writes. Scott notes
that several steel*framed towers have burned
longer, hotter . and much more intensely
without collapse. "As engineers we know what
fire can do to steel and what it can.t."
"Over 100 recorded witnesses reported hearing
and seeing multiple explosions," Rice wrote.
9

Brookman cites "numerous eyewitness accounts,
including the FDNY oral histories, of
secondary explosions ... well below the
impact floors." His letter to Congressional
representatives describes "explosive clouds
of dust and debris moving horizontally and
vertically." Brookman added: "That does not
look anything like a heat*induced,
gravitational collapse mechanism." Rice notes
that "perimeter columns weighing several tons
each were ejected laterally up to [600]
feet." His conclusion: "Not possible without
explosives." Angular Momentum Arrested As the
South Tower began to fail, the top 25 stories
tipped as a unit, photos show. "The tilting
block doesn.t look right," Brookman said. It
should "continue to rotate and fall to the
ground." Edward Knesl and Lomba say the same
thing. The failure mode of such tall
structures should have been "a fall over to
the side" (Knesl) and "a toppling of the
upper floors to one side ... not a
concentric, vertical collapse" (Lomba). "It
looked like an explosive event," Brookman
said. "[The upper section] began tilting
toward the damage

zone, and then suddenly dropped straight down
and disintegrated in the process." Building
7.s Mystifying Implosion Baffling as the
Towers. "collapses" were, even more
perplexing was the destruction of World Trade
Center Building 7. "Unprecedented," says
Rice. "Unexplainable," says Huebner. "No
plane hit this building," points out Graham
Inman, a chartered engineer in London. Few
Americans have given any thought to the third
World Trade Center high*rise destroyed on
September 11th , since it was not repeatedly
televised. Kamal Obeid, S.E., ponders it. "A
localized failure in a steel*framed building
like WTC 7 cannot cause a catastrophic
collapse like a house of cards without a
simultaneous and patterned loss of several of
its columns at key locations within the
building." Videos show "simultaneous failure
of all columns," wrote Inman, "rather than
[the expected] phased approach," in which
undamaged columns would show resistance
sequentially. Though the building housed
"offices of the CIA, the Secret Service, and
the Department of Defense, among others,"
Rice notes, the 9/11 Commission left WTC 7.s
collapse out of its report. FEMA.s 2002
inquiry blamed WTC 7.s collapse on fires,
though it admits that its "best hypothesis
has only a low probability of occurrence."
Rice notes that the media have "basically
kept the collapse of WTC Building #7 hidden
from public view." The Phantom Pile Driver
Two days after 9/11, Dr. Zdenek Ba.ant
offered a rationale for the most catastrophic
structural failure in history. Seven years
later, his thesis 10 still underlies
official claims that total collapses were
"inevitable." Ba.ant.s mathematical model of
the

official story] that may have led to the
collapse of the 3 WTC buildings," he writes,
"and has stated that further study is needed,
but FEMA has not proceeded with further
research." Evidence was not just ignored; it
was destroyed. Firemen rioted at Ground Zero,
18 protesting the desecration of the dead in
a hasty "scoop and dump" clean*up of the
structural steel debris. "The destruction of
the crime scene evidence is inexcusable,"
Huebner writes. Scott laments the "masses of
vital forensic evidence" lost, and Bill
Manning, Editor in Chief of Fire Engineering
magazine, called FEMA.s investigation "a
half*baked farce." 19 Steel components were
stamped with identification numbers that
would have aided their reassembly for study,
but that reassembly never took place.
Brookman asks, "Why was the steel ... not
thoroughly examined by fire*safety and
structural experts before being shipped to
Asia for recycling?" Pegelow charges that
"FEMA hampered and distorted the
investigation," citing Dr. Abolhassan
Astaneh* Asl.s complaints in 2002 to the
House Committee on Science that FEMA held
back essential engineering drawings and
videotapes and photographs. Such flawed
methodology was accompanied by inadequate
theories that "cannot explain the loss of the
cores," Scott points out. He says FEMA.s
notion that floor connections all failed
simultaneously at the outer wall and at the
core is "not too plausible." Bill Genitsaris,
structural engineer and builder based in
Melbourne, believes that a pancake*style
collapse should have left supporting columns
standing. Such a collapse would have left at
least dozens of shattered floors in the
building footprint below. Only very small
floor sections were found, and not many of
them. Deceptive presentation further damaged
FEMA.s credibility. Tom Lackey, who designs
bridges for the Vermont Agency of
Transportation, cites the Minneapolis Bridge
collapse study as the "kind of analysis and
straightforward explanation" the WTC needs.
FEMA.s reports stack up poorly. Some of its
graphics "omit the cores altogether," says
Scott, and some depict columns half as wide
and twice as fa

apart as they actually were. Scott decries
"attempts to distort important technical
information." The Australians use more
colorful terminology: Mason says we have been
"taken for suckers;" Genitsaris says we.ve
been "stooged." Truncated and Fudged Computer
Model Undermines NIST Report (2005) NIST.s
$20 million report is generally believed, by
those who haven.t read its 10,000 pages, to
explain how fires and plane impacts destroyed
the WTC. "The report not only fails to
explain why and how the towers completely
collapsed," Brookman points out, "but it
states that the collapse became inevitable
without any further explanation." He asks why
NIST "considered conservation of energy and
momentum principles only up to the moment
prior to collapse." NIST stopped its
computerized models before the onset of
collapse," Scott complains. "No work was done
to calculate what happened during the
failure. Why are we content with this?" Ron
Brookman adds: "The complete collapse
mechanism ... cannot be .omitted for brevity.
in any comprehensive analysis."

NIST.s claim that a kinetic "attack" exceeded
the building.s reserve strength is not
supported by any calculations or "by any
evidence whatsoever or any serious structural
analysis," states Anders Björkman. While NIST
fails to show essential work on central
issues, its numerous volumes are packed with
distracting trivia. Huebner, whose
twenty*five years of structural engineering
experience includes forensic investigation of
structural collapses, compares NIST.s effort
to a "college paper where you just keep
adding [stuffing] to make the paper longer.
Lots of pages of nothing! Definitely trying
to cover up something." Brookman asked NIST
investigators to explain the "complete
pulverization of building materials and
contents" and "visibly explosive clouds of
dust, ash, and debris." He received no reply.
"I believe in the laws of physics," wrote
Brookman, "and rely on them every day."
NIST.s reports "seem to require multiple
leaps of faith in highly improbable events,"
wrote Pasternack. Computer models using
NIST.s best estimates of temperature and
damage could not even generate a collapse,
Scott points out. They.d "simply adjust the
input until the desired outcome is achieved."
NIST probably overestimated core column
damage, Scott believes, almost certainly
overestimated steel temperatures, and
definitely overestimated damage to fire
protection. So important an inquiry should
"rely on logical deduction, reason and
first*principle analysis," Scott says, "not
circular reasoning and adjusting models to
get agreement with a preconceived
explanation." 47-Story Building 7.s
Near-Freefall Collapse Defies NIST Report
(2008) "We.ve had trouble getting a handle on
building No. 7," NIST.s Dr. Shyam Sunder
acknowledged to New York Magazine over two
years ago. David Topete, S.E., asks why no
other nearby buildings collapsed when some
were much more severely damaged by fire and
Twin Tower debris. NIST.s recent report
blames one buckling column, number 79, for
WTC 7.s global and near*symmetrical collapse,
yet characterizes WTC 7.s fires as "normal
office fires" which only burn twenty minutes
in any given location before moving on.

Obeid rejects the suggestion that one failing
column could pull adjacent columns down. "It
is not possible for a local failure within
the lower structure to spread horizontally,"
he wrote recently. "Such a failure would
cause a break*away ... instead of pulling the
structure with it." Even if NIST.s horizontal
progression were somehow triggered, Obeid
says, "the building would not have collapsed
so neatly and symmetrically. All core columns
have to be severed at the same time to make
such a collapse." Disturbing Questions That
Must Be Answered To preserve America.s
"unprecedented freedoms," Clayton Simmons
says, "we must pursue the truth." He is
troubled by "my profession.s involvement in
this apparent cover*up and the media.s
refusal to address important questions."
Scott too expresses wonder that structural
engineers. response "has been amazingly
muted," even "uninterested." Rice found that
politicians also lacked interest. Many people
"remain willfully ignorant," writes
Genitsaris. "They believe that 9/11 does not
affect their lives ... regardless of the fact
that our freedoms are being taken from us."
Perhaps few are questioning, Brookman says,
because it.s "painful to look directly at the
events and consider the implications."
William Acri, P.E., believes that the
engineer.s oath "to hold public safety above
all else" demands that they raise questions.
If three modern steel high* rises really
underwent total progressive collapse in less
than two hours of fire, merely because of the
fires and some damage to the fireproofing,
"we need to understand WHY!" Scott writes. If
WTC 7 failed from a localized fire event,
Inman asks, why didn.t the owners and
insurers sue the designers? "Either the
building design was criminally faulty, or
other causes not related to the structural
design or fire" brought down WTC 7, he says.
Why Should Science-Based Forensic Evidence Be
Taboo? From all across America, and from
Australia, Canada, the UK, and France, the
structural engineers we spoke with for this
article join more than 675 other

Architects and Engineers for 9/11 Truth in
calling for a new investigation into the
catastrophic destruction of the three World
Trade Center high*rises on September 11. "The
implications of the controlled demolition
hypothesis as outlined on the AE911Truth.org
website are staggering," says founding member
Richard Gage, AIA. "We therefore invite all
Americans to examine the science*based
forensic evidence very carefully and come to
their own conclusions." Lomba.s conclusion,
drawn from his initial perceptions and
validated by subsequent developments, is
clear: "Even if, for the sake of discussion,
we accept the hypothesis that the fire
protection was damaged and the fires somehow
weakened the steel frames, that still does
not explain the relatively concentric nature
of the failures." Scott challenges his fellow
structural engineers: "The building
performance on 9/11 matched controlled
demolition. It does not match fire*induced
collapse. We have the expertise to discern
this. Do we have the courage to broadcast
it?"

References

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