Structure Of The World Trade Center
Steel Reinforced, Cast Concrete, Tubular
Some in the
UK still think the WTC tower core was
built as shown below. Basically a pre-stressed concrete design.
Yamasaki had reviewed the design, and found no contractor that
could build a 1,300 foot column of that
design. We all know the
towers had their stairwells and elevators inside the core. There is
no room for that in the core below.
was a "tube in a tube" construction where
the steel reinforced, cast concrete interior tube, was surrounded
with a structural steel framework configured as another tube with
the load bearing capacity bias towards the perimeter wall with the
core acting to reduce deformation of the steel structure maximizing
its load bearing capacity. All steel structures with the
proportions of the WTC towers have inherent problems with flex and
torsion. Distribution of gravity loads was; perimeter walls 50%,
interior core columns 30% core 20%.
matter what temper, no matter what bracing
is used, ends up with an overall flexation that exceeds design
parameters for deformations and failures occur. These were fact I
learned from a documentary in 1990 about the construction of the
north tower. Yamsaki's decision making process was outlined and
rejected core designs identified.
Both the WTC
1 & WTC 2 towers had a rectangular
cast concrete core structure formed into rectangular cells that had
elevators and stairways in them.
numerous people that remember the early and
very technical 2 hour show. One was a civil engineer who remembers
the documentary aired on another cable educational channel in 1995
and remembers the concrete core as they are shown below and labeled
"ACTUAL CORE OF WTC TOWERS", but as yet, is not willing to provide
a declaration certifying such. The documentary showed us the true
concrete core structure of the trade center towers. It aired in 2
segments on consecutive nights. I missed the first 20 minutes of
the second one, otherwise I watched it all. Yamasaki's design for a
torsion resistant core structure made from non flexible material,
steel reinforced cast concrete, won a competition in strength with
several others. All steel towers failed high winds because the
steel perimeter columns could take the weight but were prone to
flexing and the twisting.
documentary focused on the concrete core because
the construction of the core was a big slowdown and substantial
Core And Its Hallways
Below on the
left is WTC 1 at sunrise. The view is
not looking down the hallways, we look nearly along the long axis
of the towers core. The vertical line of light in the lower segment
is created by sunlight reflecting off the inner core walls then
shining out the core hallway.
Tower had a core oriented east and west.
The camera perspective is not aligned with the hallway as can be
seen by the orientation of the south towers roof indicating an
oblique view. The light is reflected off the inner south shear wall
at a hallway level where there is no doorway interrupting. Notice
the very slight interruptions, dark streaks, whole dark floors. The
nature of light under these conditions is to blend, blur and
obscure solid areas between the light.
We see no
light on the left side because the
doorways on the north face do not align with the doors on the east.
Above that, or the top sky lobby floor, the top floors had a
different scheme with some halls on one floor crossing both
The core of
the south tower above is oriented north
south with its long axis and had 2 halls crossing the short axis.
We see no light through it because the doors on our face only
reveal a shadowed inner concrete wall corner. See the 2 vertical,
central lines in the image below.
on right, the north tower. The interior
box columns followed the slight taper of the concrete core to a
point then had to continue vertically plumb to the roof as the
interior wall of the outside tube of the steel framework. The
purpose of this section and photo is to show the space between the
interior box columns and the tapering core face at the upper
floors. The north tower had hallways crossing perpendicularly every
other floor (diagram below). This picture of the towers is looking
due south through the towers.
north tower core was oriented east west,
so we are looking at the wide side. On the right tower fr then
project that dddistance down to a cross section. We see, from right
to left; a light space from the out side to a dark column which
represents the floor space to the interior box column, then there
is another narrow light space left of that. That is the space
between the interior box column and the concrete core face. Going
leftward we see the facing concrete shear wall, then the hallway
crossing the narrow axis, then the core face again, then the space
between the east core face, then interior box column, then floor
space to the east side of the building.
crudely altered an earlier FEMA core
diagram to show how the concrete core, interior walls and hallways
were configured through the entire height of the north towers "tube
in a tube" construction.
walls of the core were not continuos
vertically, they were interrupted by hallways perpendicularly
opposed with each floor. Doorways appeared on each floor on every
face every other floor. The tops of the interior walls of the
concrete core served as the support for the steel interior concrete
forms that had to be disassembled and lifted 40 feet to be set for
the next pour. Exterior forms were plywood.
hallway/door scheme was changed higher up. Also,
the south tower was different, 2 hallways crossed the short axis of
the core, perhaps with one perpendicular.
often referred to as the "cores" in raw
photo evidence, and what the photos really show.
photos referred to as pictures of core columns at upper
you see in the photos of tower construction
within the official story are the kangaroo cranes used to move
material, the interior forms, and elevator guide rails, or to
position the rebar hanging into the concrete pour. The steel
framework was built up to 7 floors over the top of the concrete
core being constructed inside of the steel frame obscuring the core
construction from view. Other photos when the construction is lower
show elevator guide rails. These are being mis identified as "core
columns" on some web sites.
and the tower construction.
another core tier could be formed, the
elevator guide rails had to be lowered and set in place to a level
2 floors lower than the top of the present concrete pour. They are
what is shown in the diagram at the top of this page, the FEMA
core. The guide rails are presented as multiple, narrow rectangular
tubes that supposedly ran full length for the tower.
at ground zero.
is a photo showing the bottom basement
foundation level where various columns, cut off, protrude from the
concrete bottom. There is a workman near center in the photo
wearing brown coveralls, firefighters are in the foreground. These
columns are often referred to as "core columns". The columns that
rise up from inside the concrete channels forming the interior base
of the concrete core are mostly elevator guide rails. To the right
of the workman in the background is an interior box column that has
a fresh torch cut, at an angle, with slag hanging from the cut. Its
dimensions, proportions and thickness are different. The photo is
looking north through the line of the north perimeter wall of WTC 1
from just west or perhaps still inside the tower core
were the full length steel core columns
shown in the FEMA diagram, where are they in the images below that
show the concrete tubular core of WTC 2 standing momentarily, half
fallen, without the outer steel framework? Where are they in the
photos following that?
2 CONCRETE CORE STANDING
shown on the FEMA site will not leave a
spire standing like we see below and no visible multiple, heavy
steel core columns are seen in photos. No part of those cores could
have this appearance as it is halfway to the ground Above.
available images to show what the core
I saw being built in the documentary was.
Below is an
image of the top portion of WTC 2 as it
falls and is about to hit WTC 3. I would expect to see doorways,
but do not, and assume that the top 2 floors of the concrete core
were different structurally than those below where a number of
floors had hallways crossing in both direction.
arrow points to the core. The brownish gray
well lit roof and above wall face left are the core. A basic cube
shape inside the perimeter walls descending with it.
attempt to explain and identify the
building elements as the are partially seen inverted and being
ripped apart by the free fall descent of a portion of the steel
reinforced tubular cast concrete core.
fine red line approximates the top edge of the
tower faces and what was the horizontal plane of the top of the
tower. The fine circular blue line shows the counter clockwise
rotation of a group of panels of perimeter box columns that are
fastened by floor beams near the face corner that was below the top
by the length of the face corner.
fine green line shows the approximate exterior
face corner of the building and the heavy green arrow points to the
edge of the perimeter box column panel that was aligned with the
fine green line.
image of a spire that stood for 14 seconds
comprised of one corner of the interior box columns that were
fastened to the outside of the concrete core. This connection
between interior columns and the concrete made the core a load
bearing and anti torsion element for the steel framework configured
as a tube around the concrete tube comprised of four smaller
vertically interrupted tubular elements formed by the interior core
photo has a comb like shape of the remnant
of the reinforcing bars of the core, briefly standing. The FEMA
core cannot leave this shape. There are too many elements and they
are too small. The box columns in the spire image above are about
the same size as the steel columns the core was supposedly made
from. There were 47 and they were hand fabricated in 40 foot
sections then 100% welded in place. The below photo was taken at
approximately the same distance.
Below are a
long row of 3" rebar on 4 foot centers
seen at approximately 7500 feet.
The slope to
the top of the rebar was mentioned in
the documentary. The engineers specified that the concrete pours
not terminate with level opposing joints across the tower to
maximize the strength of the tubular concrete tower core as an anti
torsion element. Also the rebar was to be welded in series of butt
joints in a slope across the walls of the core. Slopes ran in
opposite directions on opposite sides maximizing torsion resistance
of the tube. The slope of the tops of the rebar in the photo below
Robertson, whose firm is responsible for
three of the six tallest buildings in the world, feels a sense of
pride that the massive towers, supported by a steel-tube
exoskeleton and a reinforced concrete core, held up as well as they
did—managing to stand for over an hour despite direct hits
massive commercial jetliners.
engineer Robertson, “If they had fallen down
immediately, the death counts would have been unimaginable,”
says. “The World Trade Center has performed admirably, and
involved in the project should be proud.” The buildings were
designed specifically to withstand the impact of a Boeing 707, the
largest plane flying in 1966, the year they broke ground on the
Description of the World Trade Center
towers of the World Trade Center were
essentially two tubes, with the north tower (1,368 feet) six feet
taller than the south tower (1,362 feet), and each were 110 stories
tall. Each tube contained a concrete core, which supported only the
load of the central bank of elevators and stairwells (Snoonian and
page has some confusion about the
construction sequence of steel and concrete.
Each of the
towers, in other words, was held up by
its reinforced concrete core and the world's strongest curtain
walls. Without the usual steel skeleton, the open floors allowed
unprecedented space and flexibility. Between them, the two
1,350-foot-high towers provided 7.9 million square feet of rentable
floor space, roughly the equivalent of fifty city blocks.
Has A Concise, Accurate Structural
At the heart
of the structure was a vertical steel
and concrete core, housing lift shafts and stairwells. Steel beams
radiate outwards and connect with steel
uprights, forming the building's outer wall.
Domel, Jr., Ph.D., S.E., P.E. November
for construction of the World Trade
Center took place on August 5, 1966.Tower One, standing 1368 feet
high, was completed in 1970, and Tower Two, at 1362 feet high, was
completed in 1972. The structural design for the World Trade Center
Towers was done by Skilling, Helle, Christiansen and Robertson. It
was designed as a tube building that included a perimeter
moment-resisting frame consisting of steel columns spaced on
39-inch centers. The load carrying system was designed so that the
steel facade would resist lateral and gravity forces and the
interior concrete core would carry only gravity loads.
received a Ph.D. from the University of
Illinois at Chicago in 1988 and a Law Degree from Loyola University
in 1992. He is a licensed Structural Engineer and Attorney at Law
in the .State of Illinois and a Professional Engineer in twelve
states, including the State of New York. Dr. Domel is authorized by
the Department of Labor (OSHA) as a 10 and 30 hour construction
link for the following does not respond.
Trade Center towers were an unusual
design, at least at the time they were built. Their support
structure is called a 'bundled tube', or in engineering terms, a
glass curtain wall structure. What this means is that the buildings
are tubes, made rigid by a lattice of steel beams on the outside
walls. These vertical columns are strengthened by horizontal beams,
and this design is what helps support the building, and keep it
stable in high winds. An inner concrete core houses the elevators,
and provides additional vertical load support
Did the Trade Center Skyscrapers Collapse?
for 9/11 Truth
Overview of evidence for controlled demolition - Scholars for 9-11
term "PULL IT" and industry term prior to 9/11 ?
HOT DID THE JET FUEL HEAT THE WORLD TRADE CENTER?
truth activists email the news
Videos on the World Trade Center Demolition
AttackOnAmerica.net - Proof Of Controlled
Demolition At The
Towers - 9-11
Collapse WTC7 - 9-11 Review
Video Evidence of Explosives In The Twin Tower Collapses
'Did' those WTC Buildings Collapse?
PROOF THE TWIN TOWERS WERE DELIBERATELY DEMOLISHED