Why It Should Be Obvious by Now That the WTC Towers Were Brought Down by

Controlled Demolition.

The "official" model for the collapses is that plane damage and fire weakened the structure enough at one floor to cause an upper section of building to break free, causing this upper section to drop down with tremendous force, enough to not only break through the next floor down, but with enough force to initiate a chain-reaction of cascading global collapse. The argument seems to be that once this reaction started, there was no way the lower structure had enough strength to resist this force, and so the whole building collapsed in a pile of steel beams.

There are two basic questions about this argument.

1) First, once a section of building drops down onto the lower section, will it automatically destroy the structure below it by sheer force of the huge mass being propelled downward by gravity?

The answer would seem to be NO, based on two lines of evidence:

a) For the 110 story WTC towers, the bottom layers of construction need to be far stronger than the upper floors, since the 10th floor would be required to support the weight of 100 floors above it, while the 90th floor would only need to support the weight of 20 floors. WTC1 was hit about floor 97, and thus the upper 13 floors (98 - 110) represent at most 12% of the building's total weight, but it is more likely they represented less than 10% of the total weight due to the strength issue. For the collapse of the WTC1 tower, common sense would say that a proportionally small mass of falling debris (9 - 12% of the buildings total mass) which only initially fell approximately 1 story (from 98th to 97th floor), could not crush the intact structure below, especially at the remarkable speed of collapse seen with the WTC1 collapse.

b) The recent failed demolition of the South Dakota feed mill showed how 80% of a tower was not enough to crush the bottom floor, even after the building dropped several stories from demolition.

2) Second, is it even possible for the upper section of a building to break off precipitously such that it generates large downward momentum?

The answer would seem to be NO, based on the following logic:

The most amount of dropping momentum would be obtained if EVERY supporting column on that floor (say floor 97 for WTC1) gave way at the same time and gave way completely (as if it instantly vaporized). But we can safely assume that the chances of this are infinitesimal. So, let's say that half of the supporting columns that are fire weakened give way at the same time (this is probably too many than realistic, but let's go with it). This will require the other 50% of the columns to carry the additional load. Now THESE columns will have more stress put on them. Realistically, the head-failed beams would be located on one side or one corner of the building. So, only that side would fail -- and the top of the building will rotate over and fall off -- thus NOT inducing a global collapse. Right here, we can see that global collapse induced by the sort of column failure mechanism is extremely unlikely.

But, to continue the argument, let's assume that every other column failed, all around the floor. But there is yet another problem -- if half of the columns fail, the remaining columns will have to carry two-times the load they were designed to carry. But the safety factor had to be greater than TWO for a safe structure.

So for a section of building to break off, a full 75% of the supporting columns had to fail. But now, we are getting to a probability approaching zero, making it so unlikely we can discount it as an explanation.

Here are some other considerations:

a. If a large number of columns are going to all fail at the same time, they need to be evenly distributed if the collapse goes straight down.

b. The proportion of failed columns must be greater than 1/SF (SF =
safety factor).

c. Assuming “N” number of columns fail because of heat, they will
essentially wilt. Heat does not cause brittle failure of steel. As the hot columns wilt, they will do so gradually, say within a minute -- not rapidly. This gradual wilting will not produce impact loading. As a result, the load carried by the remaining columns is gradually increased (even if over a 1-minute duration).
So, now we have a heavy building sitting on fewer columns. There is no rapid initial collapse that will start the chain reaction going.

d. The columns will only buckle if the cross bracing as also been removed. If the column buckles, it can buckle outward or inward, somewhat like an archery bow. That's what the buckled column should be like, as structural steel is a ductile material. So, the buckling column would bend and lower the floor down, gradually (again, over several seconds to a minute time frame).

e. Concrete does not turn into powder from simple pancaking of floors. See this picture from the recent earthquake in Pakistan:


There is hardly any sign of dust or powdered concrete around.


These factors all STRONGLY indicate that a precipitous collapse of an upper section of the WTC did not occur simply from plane damage and fire. The only explanation for the collapses, therefore, is some sort of explosive demolition. Explosive demoliiton also accounts for the massive dust clouds that were formed during the collapses of WTC1 and WTC2.

Similar logic holds for WTC7, except we take away the plane damage, making the whole fire-induced collapsed explanation essentially impossible.

(note: this short essay was co-written with a professor of engineering who wishes to remain anonymous)

If the towers were too flimsy to support their upper floors they would never have stood up in the first place.

Though I'm not sure how you got "0 posts"!

Let's just say that if DU ever makes me a credit card offer, I'll take it!

1)a)
I think you're confusing the strength of the perimeter wall and central steel columns with the strength of the floor subsystem. The floor subsystem only has to support the live and dead loads of what is on that floor. Plus, there is some load transferred from the perimeter wall to the central columns due to wind loads on the exterior. But, the floor essentially supported only itself and what was put on the floor. Assuming that the pancake theory is correct, if one floor collapses on a lower floor, that lower floor has it's load doubled (approximately). If that extra load were to cause the two floors to collapse on a third floor, that floor is carrying three times its expected load. That logic shouldn't change if the collapse was on the 90th or 60th floor.

1)b)
What does the failed collapse of a CONCRETE building have to do with the collapse of a STEEL building. Plus, there is no information that shows what the internal structure of the feed mill is. I really doubt that it was an open truss span within the exterior wall. Probably concrete columns and beams or prestressed concrete. I don't know what a feed mill looks like inside, but I imagine that it consists of concrete tubes to hold whatever grain is stored. Certainly nothing like the construction of WTC 1 or 2.

2)
What downward momentum? You talking about Gravity? Most things fall pretty quickly if dropped from any height.

Realistically, we don't know what specifications the WTC 1 & 2 towers were built to. No numbers have been provided for figuring out loads and failure points.

Re: the photo of the collapsed building in Pakistan. Again, you're trying to build a fallacious argument. The concrete construction is nothing like what's been documented for the WTC buildings. Since the only documented use of concrete in WTC 1 & 2 is the lightweight mix used on the floors, which was only a couple of inches thick, you can't compare thick reinforced structures with thin, unreinforced floors.


The biggest problem that I have with everyone's arguments for and against controlled demolition is that we don't have any evidence of what happened within WTC 1 & 2. My belief is that there was some sort of failures that happened some time before the obvious collapse was triggered. I can easily see floors sagging down on lower floors and superloading the floors for quite a while until a sudden failure occurs. The other problem I have is that all of the material failures that I've seen documented (things like concrete cores being compressed, or beams being overloaded or aircraft wings being stressed), the structure looks pretty good right up to the point of failure. Then there is a sudden release of the structure's integrity, accompanied by a loud bang.

(1) Why is this not visible through the big holes in the towers? Surely, the part of the floors at the impact holes should be (one of) the first part(s) to go?
(2) Why are the walls bowing inwards? NIST claims that the walls (south wall of north tower and east wall of south tower) were bowing inwards. If the link between the core and the perimeter was broken, then how could failed floor trusses pull the perimeter inwards? Or do you disagree with NIST on this point?
(3)(a) Where in the floor subsystem would the failure initiate? Are you saying a truss would "snap" or come apart at a join?
(3)(b) Even if a floor truss failed (and obviously some of them did after the impact), then why would that lead to further failure of other trusses, given that this does not seem to have happened around the impact areas?
(4) How many floors do you think have to collapse before the fall becomes visible? The firemen on the 78th floor of the South Tower didn't report any floor collapse.
(5) The floors of the technical floors aren't lightweight concrete. How come the floor subsystem collapse did stop there?

"My belief is that there was some sort of failures that happened some time before the obvious collapse was triggered. I can easily see floors sagging down on lower floors and superloading the floors for quite a while until a sudden failure occurs."
That's about the most common sense thing you could say, but as far as I can see you're in a small minority here (as far as concerns floor system failure gradually overloading other floors) - most of the other explanations advanced by those who think the towers collapsed "naturally" don't involve floors being gradually overloaded - Eagar thinks the angle clips went all of a sudden, FEMA thinks the trusses failed in rapid succession and NIST thinks the trusses were so strong they pulled the building over. If you could agree on one theory, I'd find it more convincing.

1)if you look at the south tower, the top above the crash site went first. you cannot see anything thru the big holes too dark and smoke and fire.

What do you mean by "the top above the crash site"?

but you can see here in this pic the area above the crash leaning and collapsing

Are you sure this:

is the north tower?

south tower

i have corrected my mistake.

here is the actual north tower collapse. you will note that as the tower collapses the fire is forced outward as the oxygen in the building is compressed and forced out from the collapse.

and said which particular "natural" collapse theory he supports. Which one do you support? NIST? FEMA? sgsmith's? Eagar's?

there's a thread on here I though you might be interested in.

;-)

http://www.pbs.org/wgbh/nova/wtc/collapse.html

NOVA: The Twin Towers collapsed essentially straight down. Was there any chance they could have tipped over?

Eagar: It's really not possible in this case. In our normal experience, we deal with small things, say, a glass of water, that might tip over, and we don't realize how far something has to tip proportional to its base. The base of the World Trade Center was 208 feet on a side, and that means it would have had to have tipped at least 100 feet to one side in order to move its center of gravity from the center of the building out beyond its base. That would have been a tremendous amount of bending. In a building that is mostly air, as the World Trade Center was, there would have been buckling columns, and it would have come straight down before it ever tipped over.

Have you ever seen the demolition of buildings? They blow them up, and they implode. Well, I once asked demolition experts, "How do you get it to implode and not fall outward?" They said, "Oh, it's really how you time and place the explosives." I always accepted that answer, until the World Trade Center, when I thought about it myself. And that's not the correct answer. The correct answer is, there's no other way for them to go but down. They're too big. With anything that massive -- each of the World Trade Center towers weighed half a million tons -- there's nothing that can exert a big enough force to push it sideways.

I find it difficult to believe that an MIT professor of engineering is unaware of the conservation of angular momentum, which is the principle used by woodcutters to bring down tall trees with hatchets.

No, it's absolutely true. That's why in the days of the Ocean Liners,
they built them double-ended, with propellers at both ends. The Queen
Mary is 1000 feet long, and 120 feet wide. Once you get something
that massive moving at fifteen knots with all the water pressing in on
both sides, no force on earth can make it change direction. It's too
big to do anything but go straight ahead.

For this reason the ocean liners had to be aimed very precisely at their
destination docks at the time they departed. For the return trip of
course the ship would simply steam backwards, using the second set of
propellers.

Right Professor Eagar? :sarcasm:

in the density of water versus the density of air.

Yes. Water, being denser than air, makes turning an ocean liner
much more difficult than toppling a building.

That was why the ocean liners' courses had to be so carefully
plotted when they left port. A few seconds' error and they'd
miss their destination dock completely, which would then bring
the need for expensive and embarrassing barging for cargo and
passengers and refueling. ;-)

The greater density of water means that it is actually much easier to control the direction of an ocean liner because there are so many more molecules to push against. Aircraft must go much faster through the air to achieve control than an ocean liner through water.

I'm talking about uncontrol.

Eagar says gravity controls the collapse and uncontrolled toppling is
therefore impossible. The force of gas molecules (unless it's a hurricane)
are a negligible issue in building collapse, so your airplane analogy is
inappropriate. The fact that a building is rooted solidly in the earth is
far more important--the point being that asymmetrical damage to the support
structure acts in the same way as the rudder on a boat to steer the structure
in one direction or another. Eagar's proposition is absurd.

My aircraft analogy made the same point that you did - since air is so much less dense than water unless you are moving very rapidly through the fluid you can't achieve as much control as you can in a higher density fluid.

This concept of "steering a structure" still fails to incorporate the relative fragility of a building structure. Damage to structural supports causes the load to be shared by the remaining structural supports. If enough supports were damaged initially, the rest will fail whether or not the damage was asymmetrical.

means of control except fluid mechanics in air or water, and
distracts from the true point: Eagar's assertion that there
is no way to extert sideways forces on tall buildings is
absurd.

The mere fact that the undamaged supports will fail if
(sufficientiy) overstressed does not disprove the proposition
that asymmetrical damage should yield asymmetrical collapse.

But asymmetrical damage does not necessarily lead to asymmetrical collapse. It is system dependent.

What other means of control are there? :shrug:

No need for days of planning and preparation, and carefull placement of demo charges; just damage the building -anywhere- and 30 minutes later it will just fall in on itself, ending up as a pile of rubble in its own footprint.

diesel fuel will do the trick!

after four years of controlled demo theory, there is not a single piece of evidence shown that can establish the CT'er is a step closer to proving CD than there was four years ago.

The evidence, the steel, was destroyed.

And the blueprints remain a secret.

But there's the FEMA Report Appendix C.

Blueprints are not public property. They have a copyright. It is at the discretion of the possessor of the copyright whether or not to release them.

samples examined as part of the investigsation. It was not all destroyed.

What about FEMA report appendix c?

Right, it's an oversimplification to say that all the
steel was destroyed. NIST had something like 250 samples.

Apparently only the steel that would have shown the
extreme heat-stressing that would cause weakening and
structural failure was destroyed--because they haven't
got that. None of NIST's core steel shows heating above
250 degrees C.

Given that all the steel was stamped with identifying
numbers, it seems to me it would have been a worthwhile
project to recover the pieces from the impact zones.

The FEMA appendix C shows mysterious high-temperature
erosion of a WTC7 I-beam into swiss cheese and rolls of
foil. The three PhDs at the Worcester Polytechnical
Institute who studied the samples are baffled. They
postulate sulfidative attack but can't explain the source
of the sulfur.







http://911research.wtc7.net/wtc/evidence/metallurgy/WTC_apndxC.htm

may not be such a mystery:

http://www.wpi.edu/News/Transformations/2002Spring/steel.html

another obvious source would be the tons of gypsum from all the sheetrock.

Drywall (also called wallboard, gypsum board, GWB, plasterboard, SHEETROCK� and Gyproc�) is a building material consisting of gypsum formed into a flat sheet and sandwiched between two pieces of heavy paper

http://en.wikipedia.org/wiki/Drywall

sulfates:


Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms.


http://en.wikipedia.org/wiki/Sulfate


The calcium carbonate of the limestone produces pH-neutral calcium sulfate that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates. In some areas the sulfates are sold to chemical companies as gypsum when the purity of calcium sulfate is high. In others, they are placed in a land-fill


http://en.wikipedia.org/wiki/Acid_rain

Dr. Jonathan Barnett is a professor of Fire Engineering.

If drywall commonly caused massive sulfidative erosion of
steel structural members, I don't think his report would be
expressing mystefication about the source of the sulfur,
and I don't think Dr. Biederman would be hypothesizing
acid rain as a possible source.

and I gave you two. Why don't you actually make a positive contribution and give us your opinion on the source. Is your entire position based on the proposition that even though you cannot explain it yourself, you have absolute faith that the source must somehow be linked to demolition and any other alternative must be rejected out of hand? Faith base CT - got to love it!

I simply reported the facts. For me to speculate about the source of the sulfur
would be no contribution because there's no reason to think that any of the
obvious speculative sources (rugs, drywall, melted computer cases) have not been
considered by the WPI experts.

Here's a positive speculative contribution: Maybe the big unspoken subtext of their
paper (while they speculate about acid rain and ocean salt as sulfur sources) is
that maybe the erosion was in fact oxidative.

If you think drywall was the source, why don't you make a positive contribution and
suggest it to the experts?

I saw the WTC drawings (I haven't heard the word 'blueprints' in YEARS) in a post-911 DVD, the Time-Life one. They were in a drawer in a building that looks over the site.

Jesus - how many lies are you disinfo people gonna trot out. Watch the DVD.

That building was as simple and clearly read as any major skyskraper project ever built.

While they have been largely replaced by prints from electronic files, there are times that we will make blueprints. Sometimes when we need multiple copies of a drawing we'll print on vellum and then make several blueprint copies (like when we're doing as-builts of large buildings).

Some of the reproduction companies still do blueprints because we have debated eliminating our blueprinter and just sending the vellum sheets to them instead, but nobody depends just on blueprints for business - they aren't very common.

talking about vintage construction drawings. Just as we still "dial"
a push-button cell phone, and still teach our children that trains
go "choo-choo-choo", the term blueprint remains in effect.

Which is of course a semantical distraction from the true point:
the blueprints remain secret. Or, as has been argued, they're not
secret but we can't see them.

This is a side issue about which I feel strongly - intellectual rights last way too long. This is partly because of companies like Disney that want to protect their early works, but I think it is ludicrous that the plans for a building that was designed in the 1960's can't be part of the public domain. What exactly are we protecting here? Is anyone going to copy parts of the design? I hope not - there have been many changes (both in technology and building code) that make such an argument moot. Ugh.

The American Iron and Steel institute published a pamphlet on the World Trade Center in approximately 1964. "Contemporary Steel Design," Vol. 1, No. 4. The publication is now available in pdf format. The files are very large so it could take a long time to download on a slow connection. Cover, 1-2, 3-4, 5-6, 7-8, 9-10.
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisicover.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi1.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi2.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi3.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi4.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi5.pdf

criticize the NIST report based on an examination of the
limited 1964 documents you show there.

My office is doing a survey of some equipment for the VA hospital campus here in Tucson and most of the plans we have are either from 1976 or 198- (varies). We have done two equipment surveys so far (out of about 60) and what is on the plans differs quite a bit from what is actually in the field. Hospitals are a bit different from other kinds of buildings because they undergo quite a bit more revamping but the point still applies - forty-year-old plans aren't very reliable.

Talked with him at a cocktail party last night.

Google Irwin Cantor.
http://www.google.com/search?hl=en&lr=&c2coff=1&q=irwin+cantor+wtc

He said the demolition conspiracy theorists for the WTC Twin Tower and WTC 7 are "nuts".

Thought I would share that.

BTW, he thinks it's very hard to precisely dtermin how WTC7 fell, but he is fairly certain the diesel in WTC7 and damage to fireprooofing on key columns was a reason for collapse.

how that steel frame catastrophically failed. Diesel burning next to steel pillars is noted for causing buildings to collapse - I don't think. Calling those seeking a real explanation "nuts" while providing such a non-attempt at explaining is dodging the issues from someone who ought to be more interested.

Whatever the meaning of the "Pull It" quote really is is open to some discussion.

What's not, though, is that Silverstein and FDNY removed the fire teams from WTC7 to preserve life, according to his broadcast. Firefighters know how to put out building fires without being killed, so it stands to reason that they *knew* the building was going to collapse. If it wasn't collapsed by demolition at their command, they have to explain where this knowledge came from since there had never been a building collapse before in these circumstances.

the fireman were monitoring a large bulge in the building for hours before it collapsed - thats why they knew it would collapse.

Then why didn't the FEMA report mention it?

don't you? There are eyewitness accounts.

by lack of funding, lack of site access, difficulty getting the
blueprints, and lack of steel samples.

I simply find it very peculiar that these eyewitness accounts
of structural bulges and ten-story gashes in the building
did not make their way into the FEMA report. Thus I question
the veracity of these accounts.

Another point to consider is that it would be foolhardy for this fellow to say anything else, whatever suspicions he might have.

Apart from the building engineers who witnessed explosions, no one associated with the Trade Center in a professional way has to my knowledge publicly questioned the official theory, and it seems clear that doing so would gain them instant notoriety of a distinctly unwelcome sort.

FEMA
World Trade Center Building Performance Study
http://www.house.gov/science/hot/wtc/wtcreport.htm

chapter 5 (wtc7)
http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch5.pdf

page 31
5.7 Observations and Findings

"...Although the total diesel fuel on the premises contained massive potential energy, the best hypothesis has only a low probability of occurrence. Further research, investigation, and analyses are needed to resolve this issue."

Two buildings with un-symmetric damage and different time to collapse windows both resulted in identical symmetric collapses. Each in slightly more time then gravity would propel them to the ground without any resistance from a majority of its floors bellow the point of failure.

And here in lies the problem�

The building bellow some 80 floors were designed to each resist the load of the floors above, but that is only part of it. They were designed to bare twice the potential load so in essence the building was built so that each floor could handle the load of twice as much as the total floors standing above it.

The building didn't slow down; as a matter of fact it speeds up before it turns to dust poof right in front of all those cameras. Gravity is a strong force but it cannot propel an object to the ground without affecting what stands in its way. In the way of the falling part is still a majority of the double strength floors pushing what ever volume back against the force of gravity pulling on it, the only force available to propel any naturally falling object to the ground. There is also a large volume of air that must move for the building to be able to reach such speed without resistance just like in the video. If you move any mass, it requires energy to make it move, if any mass is in the way of another upon interaction the mass with the greater force will loose force to the least mass.

The gravity load of the building pushing down was not enough to both overload a sequential and almost symmetrical collapse of building while at the same time propelling that load to near freefall speeds. Because buildings even in �documented� controlled demolitions have to accelerate to reach the ground. The floors bellow have to move away from the space the falling debris above will need to pass through. Since the majority are uninjured prior to the collapse and are still resisting twice as much as what ever load is pushing back down, where the fuck did all the extra energy to pulverize these buildings into clouds of dust come from?

An acceleration to near freefall means that each piece of the falling debris would while chewing up the double strength �still structurally sound� floors bellow not loose any momentum due to this interaction.

For every action there is an equal but opposing reaction, not however when two unsymmetrically damaged Twin Towers symmetrically and nearing the rate of freefall collapsed to their foundations.

Apologies to anyone who has already pointed these out:

1. The official assumption is that the weight of floor x+1 (trusses, concrete) fell on floor x and overloaded it.

But why would it overload it? Wouldn't floor x be designed to carry at least that much additional live load?

2. Another assumption is that the complete floor assembly of level x+1 suddenly freed itself and fell on floor x.

But why would that happen? One side always fails first, which would cause the floor diaphragm to simply hang from the other side like a tent.

It's like that trick where you cut three tabs into a piece of paper, then pull the outer tabs -- the inner tab never tears free from both outer tabs at once; it remains attached to one or the other. So even if a floor collapsed, only a fraction of its weight would load the floor below.

3. There were lots of steel beams in every floor, some more than others, but even floors with mostly trusses had beams in the corners for the trusses to attach to. Presumably, these beams were not just "clipped" to columns. So only the portions of the floor diaphragms between beams could have collapsed, and those only only partially, and they could only have overloaded lower floor sections also between beams.

In other words, the idea of a cascading series of floor diaphragm failures is nonsense. But then so is the idea that it could have led to a complete global collapse.