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Corrected perimeter column data info given on the page Structural Data for WTC 1, 2. On that page it was stated that the NIST documents state:
Fourteen grades of steel were used in the construction of the perimeter columns with minimum yield strengths of 36, 42, 45, 46, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 100 ksi.
However, as the page now indicates, NIST NCSTAR 1-3 actually says:
PC&F of Seattle, Washington, fabricated the perimeter wall panels. The perimeter panels were comprised of three important subassemblies: the columns, the spandrels,
and the truss seats. The structural plans called for the columns to be fabricated from 14 grades of steel with Fy = 36, 42, 45, 46, 50, 55, 60, 65, 70, 75, 80, 85, 90,
and 100 ksi, although PC&F received approval to upgrade all 85 and 90 ksi steels to 100 ksi. Above the 75th floor, more than half of the columns had yield strengths
between 55 ksi and 70 ksi, inclusive. The spandrels were fabricated from twelve grades of steel with Fy = 36, 42, 45, 46, 50, 55, 60, 65, 70, 75, 80, and 100 ksi (again
with all 85 ksi steel upgraded to 100 ksi). The truss seats were specified to be fabricated from steel with Fy = 36 ksi minimum.
