Why Didn't WTC #5 & #6 Collapse?
I was surprised not to find a thread about this. If there is one and I missed it, I apologize in advance.
Here is a video of WTC building #5 on fire.
If people call WTC building #7 a 'raging inferno' as I have heard some call it, then what would they call this?
Once again *SNIP* - different buildings with different construction
WTC 5/6 were 9 story conventional buildings using standard internal
steel structure
WTC 1/2 used totally different construction methods - using tube
structure with outer shell of lattice columns and inner core columns.
WTC 7 had large span cantilever transfer beams (almost like a bridge) to
support the structure over the Con Ed substation on the lower floors
WTC 5 construction
5 WTC was a steel-framed office building, with 9 stories. The structure was "L"-shaped and occupied the northeast corner of the WTC site. Overall
dimensions were 330 by 420 ft (100 by 130 m), with an average area of 120,000 square feet (11,000 m²) per floor.
Floors 4 through 9 suffered partial collapse and/or fire damage. Floors 1-3 were undamaged. Some of the collapse was due to impact from steel and
debris from World Trade Center 1 (North Tower). Other collapsed sections were due to fire damage. Portions of internal collapse and burnout were found
on upper floors, mainly floors 6-8. The exterior facade suffered severe fire damage. The upper floors (5-9) were on fire after the second tower
collapse. A section of the fuselage from United 175 landed on the top of the tower.
The FEMA/ASCE Building Performance Study Team team found that some connections between the structural steel beams failed in the fire. This was most
apparent in the collapse of World Trade Center Building 5, where the fireproofing did not protect the connections, causing the structure to
fail.[1]
Also parts of WTC 5 collapsed from fire damage - so much with the chant
"No steel frame building collapsed from fire damage...."
WTC 6
Debris from the North tower covered the area near 6 WTC digging a deep crater into the building's basement. The building's ruins were demolished to
make way for reconstruction. AMEC Construction handled the demolition,[1] in which the building was weakened and then pulled down with cables.
Now there's that "Pull" thing...
Can see center of building was crushed - almost like a donut
WTC 3 (Marriott Hotel) suffered simialr damage where most of building was
crushed by debris impact yet one corner stood intact
As for WTC 7 - the picture is of the undamaged (By debris) North face
here is video of South face - notice heavy smoke pushing out from most
of the south face
Clips 4 to 8 are of south face - count how many floors can see smoke pouring from
Black building in right foreground is WTC 6, gray concrete building to left
is Verizon (140 West St)
Mod edit: Insult removed.
Courtesy Is Mandatory: Read this link
[edit on 12/16/2008 by Hal9000]