The WTC Cores As Seen In Construction Photos
This picture is of the North Tower during construction.
The reader can see that the structural design of the WTC Towers is
really not that complicated. They each consist of
1) A Core structure
2) A “webbing” of perimeter columns all around the outside.
3) Large, open floors for office space. These floors are connected
to the outermost core columns on the inside, and the perimeter
columns on the outside.
Each building was built basically by repeating this pattern over and over again with very few exceptions.
The diagram below shows the layout and labelling of the core columns
according to the blueprints. North is up.
Please compare this diagram with the first picture. Can you see which columns are which? How the blueprints accurately depict the core?
Can you see how the flooring in the entire office area is directly supported from the core by only the 24 core columns on the outside of the core? (This point will become much clearer in pictures to follow.)
Notice that there were 4 large cranes used during construction.
They were supported by firmly attaching their bases to the large
columns in each of the 4 corners the core.
Each crane base fit inside the rectangular spaces just inside the 4 corners, shown as rectangles in the diagram above.
It is fair to say that the architects and structural designers involved in the construction of the towers felt confident that the box columns surrounding these these 4 corner spaces were especially strong and secure.
After all, they were chosen as the supports to hold 4 cranes and all their payload simultaneously during the entire construction process.
We can see 2 of these cranes below.
In the above picture we get to see only the tops of the core columns sections with the floor built up around them.
The builders would then place another section of core columns on top of the ones seen in this picture.
They would weld and cross-brace the next 3 story part of the core.
Then another 3 floors would be built and the whole process would repeat itself over again.
If we remember that the cranes are located inside the corners of the core, we can identify each column.
The row of columns closest to the viewer is either row 500 or row 1000. These are the biggest and strongest columns in the building.
The pair in the foreground to our right are columns 504 and 505 (or
1004, 1005, depending which way is north).
This black-and-white photo gives us a truly unique glimpse inside the
core structure. This shows the very base of the core structure
being laid out for the north tower. These are the first 2 sections (the first 72 feet) of core box columns being laid out just over the foundation footings.
You can clearly see how the inner core columns, consisting of columns 702 to 707 and columns 802 to 806, are positioned, spaced and even cross-braced differently than the surrounding outer core structure. This is why I said earlier there are 2 distinct parts of the core: The outer and the inner core columns.
It would even be impossible to put a cross-brace directly from most
of these inner columns to their corresponding columns in rows 600 and
900, since the columns don’t line up.
This is a very informative picture of the base of the core taken during construction. This photo was taken at about the same point of construction as the other black-and-white picture shown before.
Some concrete footings are visible.
Once again please notice that the tops of all columns are at the same elevation.
The bottom level will become sublevels 5 and 4. The actual flooring of sublevel 4 is yet to be built, so you really can’t see the actual floor height of sublevels 5 and 4 from this picture. You can see the actual floor heights of sublevels 3, 2 and 1 and the service level. And as described in the essay "Floor and Weld Elevations"
, we know that
the sublevel 5 floor height is 11 feet
the sublevel 4 floor height is 11 feet
the sublevel 3 floor height is 10 feet
the sublevel 2 floor height is 10 feet
the sublevel 1 floor height is 10 feet
the service level is 16 feet
On Core Column Connection Planes (Weld Planes)
Now I ask the reader to look carefully at the picture above.
Combined with the other pictures of the core under construction, we have the ability to notice the following important facts about the core structures of the WTC towers.
Facts about the core:
1) Only the 24 outermost core columns directly support the inside part of all the flooring in the open office space area.
2) 20 of these 24 columns outermost core columns are the strongest columns in the entire building. These would be all columns in rows 500 and 1000, and columns 601, 608, 901 and 908.
3) The core seems to be made up of 2 very different parts, the outer core (the rectangular cross-braced outer region with cranes at each of it's corners) and the inner core (the part inside this rectangular region).
And now I’ll introduce another feature of the core columns:
Each core column consists of many box column sections, stacked end to end one on top of the other. Each box column section is about 36 feet long (will be verified later) and spans about 3
The elevations where each column section ends and a new one begins is the same for all core columns. Hence, fact #4:
4) There were discrete, well defined horizontal planes, roughly located every 36 feet, or 3 floors, all the way up the building, along which all the core column sections are welded together.
These evenly spaced horizontal connection planes can also be called "weld planes".
How do we know these weld planes exist? Well, NIST won’t help us out and neither will the plans. NIST is being very coy with it’s information.
We can actually see these weld planes in every one of the photos presented in this essay. The tops of each of the 47 core columns certainly seem to be at the same height in every picture in this essay and throughout the entire photo album entitled "Construction Photos".
In fact, all useful photos I have seen to date show the same even alignment of the tops of all core column sections.
(Note: This author predicted the existence of these distinct weld planes in June, 2006. Since then, the wonderful research of Lon Waters has verified this to be correct.)
In the picture above, you can see a long lateral truss connected along the outside edges of the 500 columns. This lateral brace has small rectangular protrusions of steel spaced every 4 feet or so along it's side. The floor joists that support the flooring in the entire open office space will be bolted to these metal protrusions, so this lateral braces support all the floor joists to be suspended to make the next higher floor.
This gives us further evidence that the inside connections of all floor joists in the open office space were supported directly only by the strongest, outermost core columns.
The outer core compared to the inner core.
The reader can see a rectangular group of core columns around the outside of the core with cranes at each of the 4 corners of this rectangle. This rectangle consists of all columns in rows 500, 600, 900 and 1000 and includes column pairs 701, 801 and 708, 807.
Inside this rectangle are only columns from the rows 700 and 800.
Once again in this picture we can see that the tops of all the core columns seem are at the same elevation. The tops of the columns seen actually defines the fourth weld plane from the base of the building, 2 weld planes higher than that seen in the 2 black-and-white photos seen earlier..
Open Office Flooring Joist Supports.
The joists under the open flooring between the core and the perimeter are supported from the inside only by the outermost core columns. The reader can clearly see that this is the case in the last 2 photos.
Created on 06/24/2007 12:31 PM by admin
Updated on 05/12/2012 01:14 AM by admin