The following excerpt from WikiPedia.org on 10/22/05 is typical
of claims made by theorists claiming faulty construction was
partly to blame for the collapses of the Twin Towers.
e x c e r p t
- Longspan floors supported by external columns are inherently weaker
than the traditional box frame column/girder arrangement
with internal walls.
- The bunching of all internal columns in a relatively narrow center shaft
in a building is an "all your eggs in one basket" configuration-- if that
region on any floor is catastrophically damaged (as it certainly was
by the fire in the north tower), the entire building is doomed.
This stands in stark contrast to earlier generations of skyscrapers which
utilize full skeletons of stepped columns, usually one row approximately
every 25 feet (7.6 m) from the center to the perimeter.
- The World Trade Center exclusively used lightweight materials,
especially in the facade. Had the WTC facade contained even minimal
masonry elements and/or traditional heavy steel outermost column rows,
it is unlikely the aircraft would have cleanly penetrated to the core
of each tower— a significant portion of debris and jet fuel would have
remained outside, a much different scenario.
- Single-bolt connections binding the longspan floorplates with the
load-bearing external columns were extremely lightweight for their
assigned task. One study group from the
Massachusetts Institute of Technology
has concluded the proximal cause of the south tower collapse was failure
of these bolts in the southeast corner of the building.
Double-bolts should have been used.
- The use of
cladding instead of reinforced concrete to shield stairwells.
Almost all skyscrapers, including those built since the WTC,
shield stairwells in reinforced concrete. On September 11th,
it was the collapse of all stairways above the impact level that consigned
all people above the impact zone in Tower One to death.
Tower Two had two of its three stairwells taken out above the impact
area by the plane. Some people above the impact zone survived,
as they used the third stairwell. Computer models have shown
that most of the stairwells in both towers would likely have remained
usable until the general collapse had they been shielded in concrete.
The following debunking of the above 'design criticisms'
was added to the Wikipedia article on 10/22/05,
and and has since been deleted and restored a number of times.
The first criticism omits and the second criticism minimizes
the massive core structures of the towers, which contained
47 steel box columns arranged in a footprint measuring 87 by 133 feet.
Many of the box colums had outside dimensions of 54 by 22 inches.
The denial of the existence of these massive structures is helpful
in imagining the pancake-collapse of the floors.
Perhaps it is for this reason that the
9/11 Commission Report
stated "The interior core of the buildings was a hollow steel shaft,
in which elevators and stairwells were grouped."
The second criticism asks us to imagine that the towers employed
an unusual design, atypical of skyscrapers.
In fact, most modern skyscrapers employ this design,
which groups load-bearing columns in the core and around the periphery
in order to create unobstructed office space.
The fourth criticism is contradicted by NIST's report,
which states that the web trusses were both bolted and welded to
the external columns, and that the truss-to-column connections
probably did not fail.
The failure of these connections would invalidate
which depends on the floor trusses pulling in the external columns.
It is interesting that the fourth design criticism
(that only single bolts connected trusses to columns)
was endorsed by a team of researchers from
the Massachusetts Institute of Technology
and then blatantly contradicted by
FEMA's Report showed that each truss was attached to the perimeter wall
with it top chord connected with two 5/8" diameter bolts and
a welded 3/8" gusset plate,
and the bottom chord connected with two 1" diameter bolts.
(See Figure 2-6 in the left margin.)
Shoddy Construction Theory Versus Towers' History
Aside from misrepresenting the Twin Towers' structural design,
the idea that poor design was a factor in the collapses
is contradicted by the fact that the buildings stood as long as they
did without any indication that they were structurally deficient.
They withstood many winter storms subjecting their upper reaches
to windspeeds of over 100 mph.
Bolts Contributed To WTC Collapse, CBSNews.com, 10/28/02
page last modified: 2006-01-30
Copyright 2004 - 2011,911Review.com
revision 1.08 site last modified: 12/21/2012
This video frame from the documentary
Up From Zero
shows the base of one of the core columns,
apparently measuring 54 inches by 22 inches,
excluding the flanges.
This photograph, on display at the
Skyscraper Museum in New York City,
shows one of the Twin Towers during construction.
The left of the image is dominated by the edge of one building's core.
It corroborates accounts that the columns forming the core's
outermost edge were 54 inches wide.
Figure 2-6 from FEMA's Report, showing the truss-to-column connections