It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Thank you.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Fire protection
Sprayed-fire resistant materials (SFRMs) were used to protect some structural steel elements in the towers, including all floor trusses and beams.[60] Gypsum wallboard in combination with SFRMs, or in some cases gypsum wallboard alone, was used to protect core columns.[60] Vermiculite plaster was used on the interior-side and SFRMs on the other three sides of the perimeter columns for fire protection.[60] The 1968 New York City building codes were more lenient in some aspects of fire protection, such as allowing three exit stairwells in the World Trade Center towers, instead of six as required under older building codes.[61]
After WWII the builders complained about building codes. They said they were too restrictive and specified every detail of construction. They called the old building codes “specification codes”. They complained the codes specified the size and type and some times even the make of a product used in construction. They decried the specification code as old fashion. They wanted the building codes changed to what they called “performance codes.” They wanted the building codes to specify the performance requirements only; and, not specify the size and type of building material to use. For example, with fire resistive requirements they wanted the code to state just the hours of fire resistance (one, two, three or four hours) required by law; and not to state the specific type and material used to protect structural steel and enclosures for stairways and elevators shafts. For example, a performance building code states: the steel has to be protected against heat of flames for one, two, three or four hours during a fire. It does not state what to use as a fire resisting material. This performance code signaled the end to concrete encasement fire protection and allowed a spray on fire protection for steel and plasterboard enclosed stairs and elevator shafts. Builders hailed the New York City building code of 1968 as a good performance code. However, some fire chiefs decried it as a law that substituted frills for real construction safety. The asbestos spray on coating of steel trusses used in the WTC towers was considered by Chief of the New York City Fire Department, at the time, John T. O’ Hagan to be inferior to concrete encasement of steel.
Originally posted by GenRadek
WTC Design
So instead of concrete, it was gypsum wallboard protecting the core columns and sprayed-fire resistant materials. No concrete.
And if you look at all the photos of the clean up, there are no columns surrounded by concrete at all. Even in a collapse of this magnitude, there would be visible evidence on most of the core beams of concrete on it. The "powder" we see is the gypsum wallboard (drywall) that was surrounding the core which got pulverized in the collapse and it is very easy to crush.
Originally posted by GenRadek
reply to post by Griff
But did you check where was the concrete placed? Was it only on the first floors, sub-levels, or throughout? I never said there wasn't any on the floors of the core. Afterall, people did have to be able to stand up to be able to get into the elevators and stairs, so its no surprise there was a light concrete floor on each floor of the core, plus the stairs..
What is meant by cementitious?
The term cementitious as defined by ASTM or Underwriters Laboratories Inc. applies to all fireproofing that is wet mixed and then pumped as a slurry. Cementitious does not refer to portland cement content.
Originally posted by GenRadek
reply to post by Griff
I do recall that they did use some heavy slabs as decorative objects around certain core areas.
But did you check what it says right above the circled area?
"Criteria for Design Floor Inside Core Unit Dead Load"
So it could also go back to what it means with the stairs and shafts.
Originally posted by GenRadek
Just speculation on my part, but it could be, in reference to loads on the beam from having the concrete flooring, or concrete partitions. Though I maybe wrong on it, I'm no engineer
And you are right, it would be easier if we could get our hands on the original documents from years before 9/11, and nothing that could have been tainted by either side afterwards. (ie the "Truth Movement or NIST)
Originally posted by GenRadek
My problem with the idea of having concrete that was poured around the columns is the extra weight, and doesn't it make it a little more rigid, kinda cutting down on the whole flexibility idea behind the design? I was also thinking of the stairs themselves. Those had to be concrete, as most stairs usually are. (But hey! If the columns WERE encased in concrete, then how would they have been able to be cut by any sort of "thermite"? Right? )
Heh, you are right about the scans though. In this day and age you'd think we'd get something better than this.
Originally posted by GenRadek
reply to post by Griff
Hey Griff, hang on a sec on that one slide with the columns and concrete. I was just looking through the entire NIST report on that part and here is something I noticed.
wtc.nist.gov...
If you can go see the pages of the PDF from 43-45, there are two different references. One is the "Beam fireproofing" where you correctly got the concrete fireproofing addition, and the next one on page 45 has the "Column fireproofing". The column fireproofing does not have any concrete, but just the sprayed on "cementitious fireproofing".
So wait a minute. Looks like you and I were overlooking something obvious. Would you call a core column a beam and vice versa? It doesn't make much sense as it should be obvious that a core column is a column, and a beam is a beam. Can you really use the two terms interchangeably in such plans? It seems that the core columns did not have the alleged concrete encasement as is being suggested. Maybe something else in the core (ie the "beams") had some sort of concrete, but it appears the core columns themselves did not. What do you think?
[edit on 2/21/2009 by GenRadek]
Originally posted by GenRadek
It could just be reference to the concrete stairs and floor areas of the stairwells and shafts. Those have to be concrete, at least the floors, and they have to have some fireproofing capability, though the stairwells were surrounded by the gypsum wallboarding, which was dislodged in the impacts and people did say the walls were messed up after the impact and twisting of the building..
Originally posted by GenRadek
But I am glad we somewhat cleared that up though, Griff!