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Old 28th March 2007, 06:00 AM   #8
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The detailed architectural drawings make clear what official reports have apparently attempted to hide: that the Twin Towers had massive core columns, and those columns ran most of the height of each Tower before transitioning to columns with smaller cross-sections.

...Neither Report discloses dimensions for core columns -- dimensions that are clearly evident in the architectural drawings.

Hoffman is dead wrong, although I did catch an error in NIST's description of the box columns. Who wants to send him an email? I have to get to work.

NIST NCSTAR 1-3A Contemporaneous Structural Steel Specifications

Section 2.1.2 Core Columns

Core columns were of two types: welded box columns and rolled wide flange (WF) shapes (Fig. 2-6). The columns in the lower floors were primarily very large box columns as large as 12* in. by 52 in. (0.30 m by 1.32 m) composed of welded plates up to 7 in. (178 mm) thick. In the upper floors the columns shifted to the rolled WF shapes. The transition floors are indicated in fog. 2-6 for each of the core columns. Core columns were typically spliced at three-story intervals. The splices in the impact and fire zones were at floors 75, 77, 80, 83, 86, 89, 92, 95, 98, and 101. Diagonal bracing was used at the mechanical floors and in the area of the hat truss. Core box columns were 36 ksi or 42 ksi. Core wide flange columns were specified to be one of four grades, but were primarily 36 ksi and 42 ksi steel; only about 1 percent of all the core columns were made of 45 ksi or 50 ksi steel.

The core area was framed conventionally with beams. There were numerous openings in the core area floor for elevators and stairwells. Since fewer elevators were needed at the upper floors, part of the core area was not needed for services. In Fig. 2-7, the dashed line shows the perimeter of the core, and shaded areas indicate typical enclosed areas for elevators and other services.

*This should be 22 in. by 52 in.
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