Did Bombs Topple the WTC??

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You asked for comments. Granted, several of us (well, me) were somewhat rough in our response (I, personnally, knew one of the victims from the pentagon and found the sites you listed offensive).

But now you're going to run away when evidence from numerous sources is presented contrary to your beliefs. If you truly believe the pentagon was not hit by a large aircraft then please present more arguments and evidence. Although another thread may be in order, but I believe these are related enough to be in the same thread.

In the immortal words of Andre the Giant, "My way is not very sporting."

 

If you want to talk about Pentagon then create a seperate thread.
And no, I'm not running away. What ever aruguments I will posts it's obvious that you will not agree with them.

 

Well, I do seem to have posted the views of someone less than the world's leading physicist. So I suppose I should follow them up with the views of Dr. Griffin, as given in his book cited above. I found on enquiry that the Claremont College of Theology is a reputable institution, not a refuge for crackpots, although that doesn't speak for Dr. Griffin himself. I was impressed by the sober, even tone of his book, given the inflammatory nature of his subject. The questions he raises are disturbing, but he is of course a layman, as I am also. But quite a few posters here seem qualified to give a more professional opinion. I should add that I post these in a spirit of concerned inquiry, not of polemic. [My comments are in brackets.]

"Six Problems in the Official Account

"One problem iis that fire had never before caused steel-frame high-rise buildings to collapse, even when the fire was a very energetic, all-consuming one, such as the 1991 fire at One Meridian Plaza in Philadelphia....The Commission says that to its knowledge, 'none of the (fire) chiefs present believed that a total collapse of either tower was possible'.

"A second problem is that the fires, especially in the South Tower and WTC-7 [which also collapsed], were quite small. We have all seen pictures of the giant fireball immediately after the
South Tower was hit. This fireball did not signal a raging fire inside, however, but the opposite. There was such a big fireball outside because the building was struck near a corner, so that much of the jet fuel burned up outside.. There was, accordingly, not much fuel to feed the fire inside. [Is this assertion correct, or at least more likely than unlikely?]...With regard to WTC-47, which was not even struck by and airplane, photographs show that there were fires only on the seventh and twelfth floors of this 47-story building. And yet it collapsed, while Buildings 5 and 6, which had raging fires, did not.

"A third problem is that if the Twin Towers had been brought down by the heat of their fires (perhaps combined with the impact of the airplanes), the North Tower should have collapsed first. It was struck seventeen minutes before the South Tower. It also had larger and hotter fires....However, the South Tower collapsed first, 29 minutes before the North Tower did....In other words, although the South Tower had smaller fires, it collapsed in 56 minutes, whereas the North Tower, with bigger fires, collapsed only after an hour and 42 minutes....[Is there any merit in this argument?]

"A fourth problem is that, even had the fires been raging throughout the Twin Towers and Building 7, they should not have been nearly hot enough to melt steel, because ordinary hydrocarbon fires--such as fires based on jet fuel (kerosene)--can at most rise to 1700 degrees Fahrenheit, whereas steel begins to melt only at about 2770 degrees F. [Is this correct?]

"A fifth problem is that the collapse of Building 7 was recognized as being especially difficult to explain. FEMA, which was given the task, admitted that the best possible explanation it could come up with had 'only a low probability of occurrence'.

"A sixth problem is that the collapses of the Twin Towers and WTC-7 had ten characteristics that are standard features of 'controlled demolition' collapses, which are produced by explosives placed throughout a building and set to go off in a particular order. Namely:

1. Each collapse occurred at virtually free-fall speed.
2. Each building collapsed straight down, for the most part into its own footprint.

[These first two points have always impressed me. How likely is it, in fact, that three skyscrapers--two of them struck by airliners--should collapse in such fashion from impact and fire. Bion implies in his answer above that this is in fact normal. Is this true?]

3.Virtually all the concrete was turned into very fine dust.
4. In the case of the Twin Towers, the dust was blown out horizontally for 200 feet or more.
5. The collapses were total, leaving no steel columns sticking up hundreds of feet into the air.
6. Videos of the collapses reveal 'demolition waves', meaning 'confluent rows of small explosions'.
7. Most of the steel beams and columns came down in sections that were no more than 30 feet long.
8. According to many witnesses, explosions occurred within the buildings. [But how reliable is this testimony?]
9. Each collapse was associated with detectable seismic vibrations (suggestive of underground explosions).
10. Each collapse produced molten steel (which would be produced by explosives), resulting in 'hot spots' that remained for months. [But wouldn't fire, if it were hot enough, have produced the same phenomena?]"

David Ray Griffin
"The 9/11 Commission Report:
Omissions and Distortions"

From a physicist to a theologian: now there's food for comment!

 

Hmm, I do have a question though, about people bashing Griffin's theories: How did the buildings fall straight down, turn concrete into dust (instead of chunks), and why were the collapses complete? While I don't like taking the side that 'because there is no evidence against these theories, they must be true', where is the proof against his theories?

 

As I wrote earlier: I think these weren't explosions but objects catapulted out due to high pressure. They dust clouds were IMO to tiny to come from explosions.

As for the melting of steel. The points do not include what the impact of a high-speeding plane does to the structure nor the possibility that it was probably sufficient that the steel beams became weak (not molten) because of the fires.

@Saber: I don't know why the collapsed stright down. Maybe the internal structure was giving in first and the rest fell down around it.

But the completness of destruction could stem from the height of the buidlings. This means the falling debris builds up a lot of momentum and shatters when it hits other buildings or the ground.

 

A quick back-of the-envelope (spherical-cow-modelling)-calculation regarding the melting steel

Mass of plane= 450,000pounds=204116kg =m (205000)
Velocity of plane =600mph =308.67 ms^-1 =v (310)

So the kinetic energy of the plane is (0.5mv^2)
about 10^10 joules

Now the heat capacity for steel is 450 J/kg (ie it takes 450J to rasie the temperature of 1kg of steel by 1 degree)

So assuming 5% (this is a slight over estimate) of the kinetic energy was was "absorbed by the steel)

ie 5*10^8 J availabe
Temperature to melt steel = 2800 degrees (assuming mild steel frame)
Temperature of steel initially (approx room temperature) = 25 degrees (temperature of day)

So energy required to melt 1kg of steel is 1.1*10^6 J

So 5% of the plane's kinetic energy could melt only 400 kg of steel
This would be at point of impact, assuming the plane hit one of the steel supports.

Just to put this is perspective the mass of steel in the antennae of the north tower was 354 tonnes

Thats quite a big diference.


Now would the 400kg of steel do however correspond to around 4 times the total mass of the bolts(the ones that simultaneously broke) on ALL floors.
However instantaneous transfer of heat is impossible so the structure if if collapsed due to this the floor impacted would have gone first, followed by the bolts nearest it
(assumes no heat losses due to absorbtion by anything other than steel)
With this the cause it would have toppled. (ie not collapsed in its footprint)

Leaving a significant fraction of the building still standing

Similar considerations for the case of the beams weakening but not melting ==> same conclusion
Towers should have toppled

And heres one of the dust clouds:
http://home.comcast.net/~skydrifter/col.jpeg

 

I'm not sure how many structural engineers are out there, perhaps they can harp in here. I work for a company within the construction industry. We have 10-15 structural engineers here and I've had the opportunity over the past few years to talk to them about a variety of items -- including the collapse of the WTC.

These buildings are designed to fail EXACTLY as the Trade Towers failed. Collapse the interior floors and the exterior walls fall in. Initially there was a fear when these extremely tall buildings started to be built that a single collapse could cause destruction for blocks and trigger a 'domino' effect -- hence this tendancy to collapse was designed into the buildings.

When steel is used in buildings designers usually use a 4:1 or 5:1 safety factor. Meaning the steel frames, girders, and wires are four or five times the strength needed to hold the load normally seen by the steel. In conditions of high winds or earthquake this factor of safety can drop to 3:1 or lower in some cases.

The force the jets hit the towers is not necessarily important for heat generated (although heat will weaken the steel) -- but it is very important when considering the safety factors involved. The extreme force put in such a small area caused extensive damage. Much of the steel would have been damaged beyond repair -- leaving the remaining steel to hold the load.

The reason a series of small explosions work for destruction of a building is because you just need to destroy enough of the supporting structure to allow the sheer weight of the building to exceed the strength of the other supports. Once the floors start collapsing, the weight of the concrete from above easily causes failure in the lower floors.

In the case of the WTC a very large single explosion caused an extreme defect in the structure -- a defect which took a little time to fail. I work with this type of thing all the time. Steel will have an immediate brittle failure if subjected to extreme forces, but can also undergo ductile failure after a time if a load near its ultimate strength is applied and left on the steel (which is what I believe happened).

The concrete powder/dust issue is really not an issue. When concrete is destroyed through heavy impact it tends to crush into powder (just from my own experience of putting >50,000 psi loads on concrete).

 

As for the Pentagon link - the square footage of the building is 6.5 million square feet - it's a massive structure. Now, I don't know if that info represents it's footprint or total floor area. The pentagon has five floors, so it is possible the footprint is 6.5 million divided by 5, which is still 1.3 million square feet.

 

Did you read those articles that I posted links to before? About every question that has been raised here is answered in those.

As for those questions raised about WTCs collapsing. They are quite stupid IMO. For example the melting of steel; the fires were not hot enough to melt steel, true, but it did not need to melt. Steel loses about 50% of its strength at 1100°F. Jet Fuel burns at a max. of 1500°F. Also from the NIST reports you can see that in some places the fire was over 1800°F.

Here is something more to read:

http://tuftsjournal.tufts.edu/archive/2001/october/features/wtc.shtml
http://web.mit.edu/civenv/wtc/PDFfiles/Chapter%20V%20Fire.pdf

 

Ah, no. The article meant others.

When the buildings crashed, you could see tiny burst of smoke shooting out of windows just below the "toppeling line". The source guessed that were because of explosions. But explosions are not that concentrated.