by Enver Masud
"The buildings have been investigated and found to be safe in an assumed
collision with a large jet airliner (Boeing 707 - DC 8) traveling at 600
miles per hour. Analysis indicates that such collision would result only in
local damage which would not cause collapse or substantial damage to the
building and would not endanger the lives and safety of occupants not in the
immediate area of impact."
That's from a February 3, 1964 memo released by the National Institute of
Standards and Techonology (NIST), the U.S. government agency responsible for
analyzing the collapse of 1 and 2 World Trade Center, and NIST's recent
analysis appears to support it.
The memo says: "The structural analysis carried out by the firm of
Worthington, Skilling, Helle & Jackson is the most complete and detailed of
any ever made for any building structure."
The February 3, 1964 memo is included as Appendix A to "Baseline Structural Performance
and Aircraft Impact Damage Analysis of the World Trade Center Towers,"
NISTNCSTAR1-2, April 26, 2006.
Executive Summary, Table E-8 of the NIST report estimates aircraft impact
speeds at 443 mph plus or minus 30 for AA 11 (WTC 1), and 542 mph plus or
minus 24 for UAL 175 (WTC 2).
Executive Summary, Finding 18 states that "the tower still had reserve
capacity after losing a number of columns and floor segments due to aircraft
impact."
In an August 30, 2006 Fact Sheet, "NIST
concluded that the WTC towers collapsed because: (1) the impact of the
planes severed and damaged support columns, dislodged fireproofing
insulation coating the steel floor trusses and steel columns, and widely
dispersed jet fuel over multiple floors; and (2) the subsequent unusually
large jet-fuel ignited multi-floor fires (which reached temperatures as high
as 1,000 degrees Celsius) significantly weakened the floors and columns with
dislodged fireproofing to the point where floors sagged and pulled inward on
the perimeter columns. This led to the inward bowing of the perimeter
columns and failure of the south face of WTC 1 and the east face of WTC 2,
initiating the collapse of each of the towers."
Kevin Ryan, a division director who was
terminated by Underwriters Laboratories for challenging the NIST
analysis, wrote:
"Of course, those of us who have actually followed NIST's investigation know
that they could not produce any "robust criteria" to establish that
fireproofing was lost through forces of vibration. Instead, NIST performed a
shotgun test to see if the fireproofing could have been lost through
shearing forces.
"The shotgun test not only failed to support NIST's pre-determined
conclusions, as was the case for all of their other physical tests, but it
actually proved that the fireproofing could not have been sheared off
because too much energy would be needed."
In the Fact Sheet, NIST says that it does not
support the "pancake theory" of collapse. NIST expects to release a draft
report on the collapse of WTC 7 by "early 2007."
---
Enver Masud, "What Really Happened to
7 World Trade Center?," The Wisdom Fund, April 17, 2006
Enver Masud, "The Book Hugo Chavez
Should Have Held Up," The Wisdom Fund, September 24, 2006
