Transcript terpconnect.umd.edu

Dial 9/11 for Evidence
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World Trade Center Building 7
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The World Trade Center
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The World
Trade Center
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FEMA: WTC 1 & 2 Debris
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FEMA: South Tower Debris
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FEMA: North Tower Debris
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WTC7: before noon
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WTC7: west side
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WTC7 final damage
Pedestrian bridge, south side
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WTC7 final damage
1st floor, southeast
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WTC7 final damage
Lobby, 1st floor (note atrium)
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WTC7 final damage
Lobby, 3rd floor
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WTC7 final damage
NIST schematic: south face 1-19
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FEMA: Building 7 Debris
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Building 7 Debris: 9/23
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FEMA: Building 7 Debris
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W
E
S
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FEMA: Building 7 Debris
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N
S
W
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Ground Zero Debris
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Larry’s New Toys
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NIST: WTC7 Structure
Basic framing layout: floors 8-20, 24-45
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NIST: WTC7 Structure
Columns and framing
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FEMA: WTC7 Structure
5th floor: 14” concrete w/embedded steel T-sections
7th floor, same, 8” concrete
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FEMA: WTC7 Structure
Trusses: floors 5-7
(transfer weight from upper columns to foundation columns)
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FEMA: WTC7 Structure
Weight transfer trusses & girders (floors 5-7)
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NIST: Collapse Mechanism
Thermal expansion of floor beams against girder
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NIST: Collapse Mechanism
Column 79 girder connection
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NIST: Collapse Mechanism
Column 79
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NIST: Collapse Mechanism
Columns 80 & 81
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NIST: Collapse Mechanism
Unsupported east floors fall on Truss 2
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NIST: Collapse Mechanism
Truss 2 fails
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NIST: Collapse Mechanism
Columns 77-78-78A buckle
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NIST: Collapse Mechanism
Core column collapse progression
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NIST: Collapse Mechanism
Damage to south face, from south
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NIST: Collapse Mechanism
Damage to south face, from west
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WTC7 Structure
Multiple-floor atrium
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NIST: Collapse Mechanism
Global collapse: part 1
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NIST: Collapse Mechanism
Global collapse: part 2
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NIST: Collapse Mechanism
Time comparison: model vs. observed
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NIST: Free Fall NOT
Roof-center pixel change
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NIST: Free Fall NOT
Roof-center fall distance
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NIST: Free Fall NOT
Roof center fall velocity
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NIST: Fuel Fires NOT
Fuel line rupture couldn’t create the problem:
• Heat would have stopped the generators that
powered the fuel pumps
• Fire couldn’t have been hot/long enough to raise
the concrete/steel temps to point of strength loss
• Would have generated visible smoke through
lourves, none was observed
• Emergency generator “day” tanks on 5,7,9 floors
– wouldn’t have added much to combustible load
– safety measures in place would have prevented reloading
– weren’t near probable collapse initiation points
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NIST: Fire Observations
Diagrams based on photos (starting ch 5.6.5, vol 1, p. “290”)
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WTC7 Steel
• Only one piece examined by FEMA (App C)
– liquid iron/oxygen/sulfur eutectic moved along
intergranular boundaries, weakening the beam
– eutectic mixture evidenced only 1000C, much
lower than expected for melting steel
• Possibilities raised by FEMA
– long-term heating in the ground
– pre-collapse, accelerated steel weakening
• Not examined further by NIST
• Raises the larger question of WTC steel
removal
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Removal of WTC Steel
Not all bite-sized pieces
Indicates not total dismemberment, but confuses
issue of what melted prior to collapse
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Removal of WTC Steel
Why is it an important issue?
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Largest crime in U.S. history
Law requires preservation of evidence
350,000 tons removed (acc. to FEMA)
Bloomberg: looking at steel doesn’t
tell anything, need computer models
• Yet said to be “highly sensitive”
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Removal of WTC Steel
Reasons given
• WTC1-2: Needed to find survivors
• WTC7
– Needed to find survivors (but evacuated)
– Putting pressure on Verizon building (but
could have just moved that)
• In any case, could have labeled, documented location, and saved elsewhere
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Removal of WTC Steel
What happened to it?
• Thousands of pieces trucked to 4 landfills
• Immediate result:
– Most sent to Asia
– Some used to build warship U.S.S. New York
– 150 pieces saved (in off-limits hangar at JFK)
• Only parts from underground and lobby area
• Who decided?
• Later (January 2007) found more
– 2 columns, 3 connected perim columns
(under road excavated for human remains)
– 1 burned column at edge of site (city: cutoff)
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Removal of WTC Steel
What did FEMA look for?
• Exterior column trees & interior core columns from 1 & 2 above
the impact zone or exposed to fire and/or aircraft-impacted
• Badly burnt pieces from WTC 7.
• Connections from WTC 1, 2, and 7, such as seat connections,
single shear plates, and column splices.
• Bolts from WTC 1, 2, and 7 that were exposed to fire, fractured,
and/or that appeared undamaged.
• Floor trusses, including stiffeners, seats, other components.
• Any piece that, in the engineer's professional opinion, might be
useful for evaluation. When there was any doubt about a
particular piece, the piece was kept while more information was
gathered. A conservative approach was taken to avoid having
important pieces processed in salvage yard operations.
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Removal of WTC Steel
What about FEMA?
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62 trips to landfills Oct-Feb
No access to Ground Zero
No permission to collect or store steel
No subpoena power to obtain building
plans (to make intelligent choices)
• Their observation of anomalies dropped
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Removal of WTC Steel
“Highly sensitive”
• Nov 26: Trucks monitored by GPS
http://securitysolutions.com/ar/security_gps_job_massive/
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Sept: criminal scheme to divert steel
Oct: found 250 tons of scrap in LI and NJ
“Geofenced” zones, “geofenced” corridors
Improved efficiency and gridlock
• Driver behavior monitored, checked, analyzed
(1.5hr lunch -> firing)
• “Loads consisted of highly sensitive material”
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