[Marxism] WTC collapse

Les Schaffer schaffer at optonline.net
Tue Apr 5 13:32:53 MDT 2005

according to a just released study -- yes, by the bourgeous National 
Institute of Standards and Technology (NIST), a group whose guidelines i 
often work with -- the WTC towers collapsed because of heat from fire 
weakening the structural steel:


What's interesting in this final report is the claim that it was 
furniture on fire that caused most of the steel weakening. according to 
this report the jet fuel was simply responsible for primary ignition of 
flammables in the buildings. the furniture fire, along with the fact 
that steel fireproofing that had been stripped by jet impact, was the 
ultimate cause of collapse.

what is not touched in the story as reported above is to what extent 
failure by building contractors to supply adequate fireproofing on steel 
supports was an additional or main contributor to the collapse. this was 
discussed early on after 9/11, and i suspect we will see more commotion 
on this should various law suits against the Port Authority proceed.

[cue conspiracy theorists ;-) ]

les schaffer

findings related to fireproofing (from page 20 of 
http://wtc.nist.gov/pubs/NISTNCSTAR1-1ExecutiveSummary.pdf at NIST):

Finding 12: Code provisions with detailed procedures to analyze and 
evaluate data from fire resistance tests of other building components 
and assemblies to qualify an untested building element do not exist. 
Based on available data and records, no technical basis has been found 
for selecting the SFRM used (two competing materials were under 
evaluation) or its thickness for the large-span open-web floor trusses 
of the WTC towers. The assessment of the fireproofing thickness needed 
to meet the 2 h fire rating requirement for the untested WTC floor 
system evolved over time:

• In October 1969, the PANYNJ directed the fireproofing contractor to 
apply ½ in. of fireproofing to the floor trusses.
• In 1999, the PANYNJ issued guidelines requiring that fireproofing be 
upgraded to 1½ in. for full floors undergoing alterations.
• Unrelated to the WTC buildings, an International Conference of 
Building Officials

Evaluation Service report (ER-1244), re-issued June 1, 2001, using the 
same SFRM recommends a minimum thickness of 2 in. for “unrestrained 
steel joists” with “lightweight concrete” slab.

Finding 13: Code provisions that require the conduct of a fire 
resistance test if adequate data do not exist from other building 
components and assemblies to qualify an untested building element are 
needed. Instead, several alternate methods based on other 
fire-resistance designs or calculations or alternative protection 
methods are permitted with limited guidance on detailed procedures to be 
followed. Both the architect-of-record (in 1966) and the 
structural-engineer-of-record (in 1975) stated that the fire rating of 
the floor system of the WTC towers could not be determined without 
testing. NIST has not found evidence indicating that such a test was 
conducted to determine the fire rating of the WTC floor system. The 
PANYNJ has informed NIST that there are no such test records in its files.

Finding 14: Use of the “structural frame” approach, in conjunction with 
the prescriptive fire rating, would have required the floor trusses, the 
core floor framing, and perimeter spandrels in the WTC towers to be 3 h 
fire-rated, like the columns for Class 1B construction in the 1968 NYC 
Building Code. Neither the 1968 edition of the NYC Building Code which 
was used in the design of the WTC towers, nor the 2001 edition of the 
code, adopted the “structural frame” requirement. The “structural frame” 
approach to fire resistance ratings requires structural members, other 
than columns, that are essential to the stability of the building as a 
whole to be fire protected to the same rating as columns. This approach, 
which appeared in the Uniform Building Code (a model building code) as 
early as 1953, was carried into the 2000 International Building Code 
(one of two current model codes) which states: “The structural frame 
shall be considered to be the columns and the girders, beams, trusses 
and spandrels having direct connections to the columns and bracing 
members designed to carry gravity loads.” The WTC floor system was 
essential to the stability of the building as a whole since it provided 
lateral stability to the columns and diaphragm action to distribute wind 
loads to the columns of the frame-tube system.

More information about the Marxism mailing list