[ExI] Melted steel

Jordan Hazen jnh at vt11.net
Sun Oct 7 00:00:52 UTC 2007

On Sat, Oct 06, 2007 at 12:49:19PM -0700, Samantha Atkins wrote:
> On Oct 6, 2007, at 9:12 AM, BillK wrote:
> > The WTC was a special case. There was very little load-bearing steel
> > in the interior,  except  around the elevators. The outer walls
> > supported the weight of the building.
> > The WTC didn't use the 'old-fashioned' steel girders and concrete.
> I have heard that it was part of the known design of WTC that it had  
> massive central support structure.     I am attempting to find pre-911  
> details of WTC construction as I don't automatically trust claims on  
> either side afterwards about those details.  They should be somewhere  
> on the web.  I am looking for clean architectural and engineering  
> documents preferably.
> - samantha

Scanned copies of the original WTC1 (North Tower) blueprints were
leaked earlier this year, and posted to several web sites, one of
which converted the raw .TIFF files for easier online viewing:


Image quality of these scans isn't the best, and even at 4896x3632
("Original" resolution) some of the text and fine details are hard to
make out, especially on a small monitor.  Printing them might help.

On 9/11, the damage to this tower from the plane impact (AA 11)
affected floors 92 through 98.

Some interesting construction details:

 - Core box columns are very thick near the bottom, gradually tapering
   towards the top; same with the perimeter columns, which are deeper
   (but not wider) on the low floors.

   I've read that the WTC design called for core columns to support
   60% of the static gravity load, with perimeter coluns handling 40%
   of gravity and 100% of lateral loads (side-to-side swaying from

 - Only one (freight) elevator shaft is contiguous through the entire
   height of building.  Apart from that, Express Elevators linked the
   bottom level to two "sky lobbies" on the 44th and 78th floors
   (these went no higher than the 78th), where passengers would switch
   to a local elevator to reach their final floor.  There were heavy
   mechanical floors above each express elevator as well... this
   division of each tower into thirds is visible in some exterior
   photographs also.

 - Within each of the stacked 1/3rd-tower segments, some local
   elevator shafts served only the lower floors, allowing for more
   open floor space on upper levels.

   See also


   although that image appears to mis-label the single freight
   elevator as an express elevator.

 - Not all core columns were adjacent to elevator shafts, although
   most were, and these extended all the way up even where nearby
   elevator shafts did not.


More information about the extropy-chat mailing list