Take the Twin Towers out of the equation.
Bldg 7….minor external damage, office fires, complete "demolishion-like" collapse. You can see the charges go off right before it pancaked severing the core columns, just like they do in a controlled demo.

Heres a short bldg 7 video…worth a look if you don't know much about it.
http://www.youtube.com/watch?v=DtGfNZFiRZI

Has anyone actually read what Operation Northwoods proposed?

No conspiracy needed….check your tin foil hat at the door.

Mark-Harrop wrote on Sep 21^st, 2014 at 9:50am:


You say it's not a conspiracy video, and yet all the related videos are conspiracy videos.  One of us is missing something.

Sorry, Mark, but the guy who actually claimed it was demolitions was a radio host.  (6:45) The guy who claimed it was brought down by fire was an engineer.  (7:45)  "Building 7 was a steel frame building and was the first steel frame building to collapse due to fire."  - Structural Engineer Ramon Gilsanz on Building 7: in the above video.

I feel like you might be confused because demolitions crews borrow words to describe their work.  Pull could mean to pull everyone out.  It could mean to pull everyone back.  It could mean to pull the building down.

Similarly, 'implosion' simply means that the building collapsed in on itself.  There are really only two ways it could fall: in or out.  It might be lucky that it fell in, or it just might be that there were more support columns that were "in the middle" of the building than were on the edge.  If an support on the edge fell first, then the building likely would have fallen in that direction.  Though, I defer to the expert, Mas, on the subject.


And besides, I really don't think our government is competent enough to pull off a conspiracy like this. 

No, I know that almost all buildings are susceptible to fire. Progressive collapse due to fire damage isn't an uncommon occurrence even though the collapse of World Trade Center was the first time it happened to any buildings with steel frames. I suggest you read the paper by Bazant if you want to understand how steel beams fail in a fire; it does not require shearing of all the horizontal beams. Your assumptions about the burning of building seven are not backed up by failure analysis of the collapse.

JAG wrote on Sep 21^st, 2014 at 5:02pm:

Academic papers include their date of publication and the dates of any revisions. You should look at it, it also addresses the temperature needed for the steel supports to fail. Originally, it was published on October 2001 after being submitted on September 13, 2001. The latest update, which is the version I linked to, was published in 2008.

Masiakasaurus wrote on Sep 21^st, 2014 at 6:20pm:


Oh boy, here we go again.

Masiakasaurus wrote on Sep 21^st, 2014 at 6:20pm:


Really? Oh my. How clever. Being a dumb blond I'd never of realised. So where is your link?

So, a paper conveniently produced within days of 9/11 supports the "official" explanation of what happened. And based on this paper the government confirms building 7 collapsed due to fire.

Yet, strangely we continue building mega structures from steel and aluminium.

Nope that's not suspicious at all.

I read the Bazant paper. A few thoughts on that.

It's quite unusual to get to recycle a scientific journal paper like that through, apparently, several incarnations over a period of years.

Peer review is a very strange animal. Referees are anonymously chosen by an editor of the journal. There is usually a rather small number (two or three), so I rest no faith whatever on that. particularly since the standpoints of referees on contentious subjects is usually very well known to the editors.

I was struck that if they had attempted to publish such a failure scheme in the Engineering literature before the events of 9/11 they would probably have been ridiculed.

If this is a new and valid model, as apparently it is, has there been any change in building codes to enforce some kind of acknowledgement of this?

I was absolutely appalled by this: "... the recent fire tests of Zeng et al.(2003), which showed that structural steel columns under a sustained load of 50% to 70% of their cold strength collapse when heated to 250C."

I wonder what happened to any structural engineer dumb enough to raise this failure mode with his clients, given the very expensive changes that would be needed to prevent it. Wait - I know the answer to that .

I assume now that it is cripplingly expensive to insure such buildings, given that a decent office fire can bring the whole thing crashing to the ground?

About 2500 F

JAG wrote on Sep 22^nd, 2014 at 1:25am:


4 points you should be aware of.
1. Steel is MUCH cheaper than reinforced concrete for high-rise structures, and since it is MUCH lighter, the frame doesn't have as much dead weight to support.

2. Steel weakens at quite low temperatures. Around 850 degrees F, most structural steels lose around 40% of their strength- but more than twice that in stiffness.

3. As each column fails due to fire, it puts more load on the columns around it. This overloads the columns and they buckle as well.

4. Jet fuel easily burns hotter than 2,000 degrees F, which is almost the melting point of plain-carbon steel! If you dump 24,000 gallons of fuel into almost any modern structure, and light said fuel on fire, that structure generally burns to the ground, and often collapses if made of steel or wood.

24,000 gallons is a lot of fuel.

Steel structures are far less vulnerable to explosives than concrete. But they are far more vulnerable to fire.

"One of the major weaknesses of steel as a structural material is its susceptibility to fire induced loss of strength as well as a change in material properties after heating and cooling.  The SCM refers you to the AISC Design Guide 19, Fire Resistance of Structural Steel Framing.  Fire behavior is an extensive topic that needs to be considered when designing steel buildings.  In this first steel design text however, we will not be spending any time on the topic as we will have our hands full learning the strength and serviceability requirements of the AISC specification.  Just be aware that a steel structure essentially loses all its strength in a normal building fire situation.  Fire safety techniques focus on slowing down the heating process so that occupants can safely exit the building during a fire event.  A dramatic example of the effect of fire on steel was the collapse of the twin towers in New York after the terrorist attacks on that city.  The collapse was largely the result of the core supporting structure losing its strength during the fire that followed the plane crashes."
quoted from http://www.bgstructuralengineering.com/BGSCM14/BGSCM002/

Notes
The max burning temperature of jet fuel(jet-a) in air is 4,040 degrees F. The melting temperature of steel is approximately 2,500 degrees F.
The most common structural steel, ASTM A36, fails at 50% load around 900 degrees F.
A candle flame can easily get over 1,000 degrees F.


Also, most modern buildings are built with fire insulation on the steel elements. This keeps the building from collapsing due to fire. The Twin Towers were built to withstand a 2 hour office fire- paper, desks, carpeting, etc burning. Those items generally burn at 1,000 degrees F.