As the collapse of the tower began, huge amounts of dust and debris
was cascading out from the building in all directions, exceeding at some
point the width of the building itself.
Amongst the debris and dust were also large sections of the perimeter
walls then in free fall.
The weight exerted on the remaining floors was therefore continuously
diminished proportionally as the collapse progresses.

As the collapse reaches the 55 floor, the weight these floors previously
held up must obviously have been dramatically reduced by the huge
amount of weight that then only existed outside the perimeter of
the building; which therefore no longer had any influence upon the further
occurrences taken place.

The question that should be asked instead of course, is, why the building
kept on collapsing while the weight exerted on it kept on dramatically
reducing itself.

The answer should be self-evident, even to the most daft and slow-witted,
i think.

Cheers

I believe what you are seeing being eject ahead of the collapse front is THROUGH the window areas and the material in gypsum wall board and other light weight material including paper. The crush front where all the mass was appears to be a storyabove the "ejected material" .

If the force of the explosion which cause this ejection around the perimeter was from an explosion strong enough to blast the floors to dust, the over pressure surely could blow out the facade. But it didn't. The facade held and their weakest part - the windows - shattered from the air pressure forced out ahead or the crush front.

The facade then without the floors' lateral support began to peel away, tipping out from considerably above the crash front.

To think that most of the 500,000 tons (reputed weight of the building) was exploded out through the windows makes little sense. Tens of thousands of tons of dust was dispersed after the collapses carried by the rapidly expanding very hot dust cloud propagating from the base of the towers after the crash. And perhaps over a hundred thousands of tons of steel sections from the core were found largely in and around the foot print with the facade panels weighing about 30,000 tons and found mostly within a few hundred feet of the towers.

That's what I see.

What about the huge weight that's no longer there

to exert downward pressure on the remaining building

still standing!

What role does this missing weight, growing in size

second by second, play in the overall scheme of things,

do you think?

Cheers

Can you please explain how and from where were these values obtained?

Curiously, you seem to embrace the evidence for explosives being used in the destruction of the WTC, yet you also to cling to other explanations of things that don't seem congruent with such an event.

I think this is a very valid point. The supposed "piledriver" is actually getting smaller and smaller as massive volumes of material are ejected laterally.

I do not see anything at the bottom of that rubble pile in either building to generate the sort of frictional heat and compressive forces Sander is alluding to. What is disintegrating the buildings on the way down is the very same forces that disintegrated the floors at the initiation of the destruction sequence. The massive dust cloud begins billowing almost immediately as the fall begins. There is never any consolidated "piledriver" acting on the lower floors and you can clearly see the destruction wave (of explosions!) progressing quickly down the facade. If this were just a "collapse" there would not be anywhere NEAR the same amount of dust and pulverization happening so early in the sequence near the tops.

I try to envision what the rubble pile from pure gravitational structural collapse would look like on the Towers and I would expect to find severely crushed, BUT SOMEWHAT INTACT pieces of office furniture, mangled chairs, water fountains, and.....most conspicuously....some very large sections of fractured, but still-recognizable FLOOR SLABS. There are NONE... And I've looked at a bunch of rubble pile pics and I've YET to see one single floor truss or floor pan. Perhaps there were some, but then again, hauling away the evidence really doesn't help us, does it.

I've looked at 1000's of photos too.

I've never even seen a toilet bowl. How many toilet bowls would there have been on every floor? What about the sinks? Computers? File cabinets? Zip. Zero. Nothing.

Here's one collection of excellent hi res photos.

Boca Digital

I challenge anyone here to find any of the above mentioned objects. Good luck!

Gravity alone couldn't have done this. Not without the help of some serious explosive power. Probably hi powered weapons that were deployed in the elevator shafts is where I would put my money.

The problem with the high powered explosives turning everything to dust is that they would likely have more over pressure and a much larger and faster moving front. The main debris canopy is associated with the descent of the tops and it crashing it the bottom. This was very much like the debris plume which shoots out from a CD, only this one too place at the strike zone.

What then happen in my view is all this mass that had collapse done on to the top, then crushed through outside the core area to the ground. To displace MOST of the mass or a significant portion of the floor and contents mass would require a huge horizontal impulse, but one that did not destroy the facade since we saw most of the facade panels with little damage and some huge sections of them came off in assemblies of up to perhaps 30 10'x36' panels. So whatever the "explosive" that might have destroyed the floors, the spandrels contained the out flow and everything went through the glass area. The force of ejection (whatever the cause) was strong enough to blow out all the glass, but not make a dent in the facade... yet supposedly turn the slabs to dust which somehow was all ejected along with everything else.

The grinding crushing vertical avalanche is something we have never seem before so it in a sense as "theoretical" as the sequence explosions top to bottom. However, it makes more sense to me than the complexity of the explosive hypothesis.

The amount of mass in those towers was enormous and if even half of it came down it would crush anything in its path. The mass broke apart on its way down but it front was always coming up against an intact floor. That floor of course wasn't in tact for long and shattered into a million pieces when the tens of thousands of tons came down on it.

I think we can agree that the slabs would hardly survive that sort of impact loading. I suspect to understand what happened we need to explore the fluid dynamics of pryoclastic flows which are when solid act like liquids. That's what was going on in the collapse I suspect.

SanderO

The concrete could not have been crushed.

Or should I ask, crushed by what?

All the matter, the building, descended to the earth at more or less free fall rates. In its descent, it experienced the resistance, more or less, of air. What crushed it?

The cloud began before the collapse was complete, besides.

The resistance of air cannot crush concrete, and concrete falling to the ground will not be pulverized.

No one is examining the effects of optimum placement and distribution. As the mass of concrete particulate is accelerated, it slows down the expanding gasses that are disintegrating the structure. Also, what is visible in video has already been slowed by up to 60 feet of floor space and blowing through the windows.

This accelerated particulate pulverizes the entire contents of the building. Before refuting anything, provide a feasible explanation for the fact of the entire contents of the building pulverized. No carpets, phones, computers, file cabinets, desks found. Nothing intact. This firefighter expresses the mystery profoundly.

http://www.plaguepuppy.net/public_html/col...20to%20dust.mpg

The front, is as large as the building face per floor at a minumum, then grows. Accordingly it is not clear what you mean. Consider the particulate slowing, suddenly you see more in videos than is seen with a quarry blast. Your view starts sooner, with a smaller wave, and the expansion slowed enough to notice. Standard demo has lots of small, slightly overloaded charges. The effect we see originate from various grids mathing the rebar c to c dimensions overlapping.

The "squibs" as they are termed are the inadvertantly overloaded edges of the floors against the spandrel plates to be sure the joints there are severed. They do have the velocity of an uncontained detonation and out run the debris wave. Otherwise the concrete panel pretty much expands equally with the gasses distributing particulate, slowing the gasses as the particulate is accelerated.

There are some things to note.

At the conclusion of the collapse a huge and fast moving wave of dust and hot gases spread away from the bottom of each collapse. This seems to indicated some thing(s) dropped down and then were forced out radially like the spray from a hose point to the ground. The cloud resembles what we see in a verinage or other CD where the top crashes down and a huge cloud radiates.

Radiating cloud from ground level= falling debris

The speed of collapse was not free fall. This means that there was resistance to be overcome which was more than air. The towers were 96% air, that is 4" slabs and 11'8" of air between them.

The impacts and destruction of each floor - breaking it free from the columns which supported it took perhaps 1/100 of a second more or less - 100 floor would add a second to the "free fall collpase time". In fact, the collapse moved a 120 ft / second of about 80 mph when it reached a terminal velocity.

The towers weighed 500,000 tons without the furniture etc. The tops sections which came crashig down weighed 18 and 33% of the total mass. That's enough to pulverized anything. What can survive as recognizable with 50,000 psi of pressure? A computer? A desk? A file cabinet? A human bone? I believe the growing weight of the collapse simple crushed everything in its path and it crushed it to fine granular size by the time it had hit the plaza level. And when it did all the lighter weight dust spread out radially with the hot gases from the friction of the collapse.

I suspect the paper was light enough to be blasted out the windows with other light weight materials like GWB dust and that explains why it was scattered all over lower Manhattan. The fire and extreme heat which caused then collapse to begin (and it likely was not from the jet fuel and office fires) was not a factor after the collapse and avalanche began. Then it was all gravity crushing the floorts and the air pressure pushing the facade away.

What would you expect would happen if you "deposited" 75,000 tons of material on one of the top floors in the lower undamaged section?

So you believe the 'weight' was growing as the collapse progressed,

while everyone else can see that the 'weight' must be rapidly diminishing

simply because of the continuing vast amount of dust and debris, as

well as the peeling off or ejected wall sections that are placed outside the

perimeter of the building!!

Interesting indeed.

Cheers

I see the collapse as related to the mass of floor material. The avalanche "released" and pushed the facade out and over. It could fall only in 3 directions out, straight down and in. We see that it is almost all outside the footprint. Some believe it was exploded off the building. I see it as being disconnected by the avalanche and pushed outward by the spilling of the mass of debris. Imaging a cardboard box which is filled with sand and gravel. The mass pushes outward and the sides bow out. Something similar happened.

Of course the avalanche produced dust from concrete and GWB which was light enough to be carried by the air. Most of this was pushed out. When the collapse had finished all the heavy debris had fallen down leaving a relatively dust free volume where the building stood. In fact in some of the video is looks as if the building's contents disappeared down a chute, pulling clean air on top of it with turbulent dust laden air at the floor perimeter-facade boundary. Unlike a stack of dropping records or "pancakes" the pancakes (floors) were crushed immediately into macro sized chunks when the avalanche front hit it, These chunks became the new leading front of the collpase with all the other floors above it in a dense grinding mass which was pulverizing itself by the tens of thousands of collisions of those macro sized chunks into smaller and small pieces. At the back end of the avalanche the pulverization was pretty much complete and everything had turned to granular sized material.

There was some macro sized material at the bottom of the debris pile but none on the top. But by the time the mass of all the floors were hitting the lowest floors the amount of crushing of that mass crushed everything into pretty fine material.

I don't "know" that the above happened. It is my hypothesis because that it what I believe when a substantial mass - 15 floors in wtc 1 and 32 floors in wtc drops down onto the top most "intact" floors. As I have mentioned many times this mass destroys the top floors sequentially from the top to the bottom (like verinage) and each destroyed floor adds to the mass of the avalanche. After a few seconds the avalanche reached a "terminal velocity" and punched through destroying each floor in about 1/100 of a second with 11'8" of "free fall" acceleration between floor impacts. However the avalanche speed was not starting from 0 at each impact as it had gathered momentum and speed. So the impacts only slowed it a tiny bit which the growing mass and momentum made each destruction that much quicker. If you imagine a tower with paper thin floors and drop a steel wrecking ball on the top floor, you would expect that the ball would descend at almost free fall acceleration as the paper floors over so little resistance to the dropping ball. Something analogous happened to the floors and they managed to slow the collapse by 10% or more so the average acceleration was about .7 or .8G.

Terminal velocity is the speed at which an object in free-fall and not in a vacuum ceases to accelerate downwards because the force of gravity is equal and opposite to the drag force acting against it.

The avalanche mass had to overcome air resistance and break every floor. The air was forced out violently through the facade window which were shattered, and into the core. The mass didn't fall through the air, it pushed it away and "new air" was sucked in behind it. Pushing the air and breaking each floors connections and integrity did slow the collapse to a max speed of about 120ft per second. We can measure this in the videos before the free fall debris canopy conceals the building.

What was that debris canopy? I believe the debris canopy was from perhaps two sources. One might have been explosions which actually got the top sections to move off column and drop down. This is very similar to verinage but was likely a two part affair; soften and or cut through the steel at about the plane strike zone with heat, and then perhaps several explosions to move the mass of the upper parts enough so that their columns had no bearing and the tops dropped. When they did drop there the "initial" collisions of the top's lower floors and the bottom's upper floors. Like verinage this was violent and sent material in ALL directions and much of it out and up. This moment is captured in the often shown image on AE911Truth of the tower's collapse which looks like a massive explosion. It may have been that and the ejection of the first collisions. It's unlikely that this simply disappear inside the building.

After the first few moments of the collisions of the two sections, the mass of the floors then began to accumulate INSIDE the lower facade and begin the actual avalanche. The destruction and accumulation of the mass at first was "arrested" by the bottom's top floors. They were able to carry some extra load. But as it built up from more and more floors landing on it it gave way and dropped and the process gathered momentum. The grinding avalanche was on! And the front of it was descending inside the facade. But that changed as the facade, with so little support laterally, peeled off and dropped in huge sections over the side landing up to 450 feet away.

The so called "squibs" are vexing. Perhaps they were light weight debris pushed down elevator shafts until they encountered the elevator pit and then spread out in the path of least resistance through the elevator doors, down the core corridor and out the windows. The shafts were in heights of 10 story increments more or less, 10, 20, 30. Just a guess.

They might have been some core column explosions to deal with the columns which would not be destroyed by the floors collapsing past them. Some would also topple because they would be left too tall and thin. But 1000 foot columns toppling could really do lots of damage outside the complex. And if the intention was to destroy the wtc complex, the perps migh have designed the destruction to do as little damage to other properties as possible and so weakening of the core columns at intervals would ensure that they didn't topple as a single column. Just a guess.

I don't know what happened and neither does the "truth movement". Everyone has an hypothesis which they believe fits the observations. I believe my hypothesis is consistent with my observations. It is how I would expect a huge mass to behave when released at as much as 1100 feet or so onto the building below with a column free floor area. A traditional frame most likely would not have collapsed as these did if the tops were pushed of column.

SanderO

Your hypothesis is not persuasive regarding the pulverized concrete, and on a few other points.

The towers were 96% air is one of those trivial points made by government apologists most often. Yes, 96% air BY VOLUME, but the by volume part is never mentioned. Yours is a ludicrous and misleading statement. It makes one want to ask "Is that with the air-conditioning on or off?"

I suspect a similar number might be calculated for any large building with similar construction. And I've been told there are NO OTHER buildings in the world that employed the design and construction (exoskeleton) that the towers did.

You say that the weight of the collapse crushed everything in its path, offering 50,000 psi as a number, with a chance at 75,000?

I have met a fellow who was actually IN the lobby of the second tower when it collapsed. He wanted to get out, but the police would not let him. Though knocked unconscious, and with a large scar on his head to show it, the man survived after several days in the hospital.

So, it did not crush him.

The pulverized concrete is MOST DIFFICULT to explain without acknowledging the presence of some sort of energy such as might be presented in explosives.

I, too have spoken with a survivor who was in the collapse - Chris Giles.

The mention of the fact that the towers vertically were 96% air is accurate and used to demonstrate that what collapsed, collapsed through mostly air. Each impact on a floor came down from the floor above - 11'-8" top of slab to bottom of slab. Each of those 11'8" drops was through air.

So let's start at the 90th floor as an example. The floor mass above has fallen on to it and it can no longer support it (the amount of weight when this happens is not important for this example. Floor 90 collapses and all the material on it and the slab itself drops down 11'8" at free fall acceleration less the air resistance. The air resistance would slow it down and since the falling material could not compress the air, it would be forced out the windows and into the core. The windows being the least strong. Along with the air all sorts of lighter materials were swept out. Let's say that this drop was slightly less than free fall. The 89th floor now faces the impact of the debris of all the floors above it (whatever was on 90) and it too fails, and fails a bit faster because there is more weight and it is moving at almost free fall. Let's say this takes 1/100 of a second. How long does it take for a car to crush down in an accident with a parked car? Something less than the speed of the moving vehicle. So the speed of the material falling slows down a tiny amount. However, with each floor it crushes, it gains mass (in this case the 89th floor) and since its ACCELERATING at slightly less than 1G, the velocity is INCREASING and the momentum is increasing as well and so each impacton a lower floor packs more punch.

A free fall collpase of 9 sec at 1 G will drop 1300 feet at .9G 1175 and at .8G 1050 feet or
to drop 90 stories take a bit over 8 seconds a 1 G, 8.6 sec at .9G and 9.2 sec at .8G

So slowing the collapse from 1 g to .8G adds 1.2 seconds to the fall. That 1.2 seconds is the resistance of the air and the slabs.

1.2 secs / 90 is just over 1/100 of a second per floor impact.

How much is a wrecking ball slowed if it were dropped on a 4" conc slab?

So the fact that the towers were 96% air is significant in computing the speed of the collapse. And the mass which was growing in size as it added destroyed floors on the way down. Yes some material was turned to dust which was light enough to become air borne and was not a factor adding to the weight of the avalanche. But most of the floor mass and contents of the floors above cam crashing on to each floor and if you simply add the loads up you can see what sort of PSI that the avalanche presented to each floor.

Although it was not a uniform "pancake" collapse as the floors were breaking apart and being crushed into smaller and smaller pieces we can use the average weight and do some calcs and discard some of it as becoming air borne and fall outside or into the core.

The slab concrete was approximately 100#/ cu ft and so it would be 33# / sf. The live load was 100 #/ sf. Let's assume it was 50% of live load per floor. The truss, ducts etc added about 15# / sf. So each SF per floor weighed 33+50+ 15 = 98 #/ SF. Lets call it 100#.

When one floor's load came down on an intact floor it added 100#/sf. This was well within the safety factor which will say was 4 times the design load. When floor floors came down on it it was at the limit it now was carrying in 400# plus it's own live load of 50# / SF. It probably broke up "slowly". It's likely that the break up came at different times depending on the concentration of the over loads.

The floor below could not handle this load as mention and it too collapsed. By the 15th collapse the 16th floor had about 1,500#/sf which is 100 psi without taking into account the motion F= MA. By now it's probably dropping at 60 mph and accelerating at about 24 ft per sec per second. What sort of force does 1500# in 1 sq1 ft have after dropping 200'? That's half the weight of a small car concentrated into a square foot! Even at floor 80 you have enormous crushing action.

How is it unlikely that this sort of force would not crush everything in its path? And this force is more than added every 15 floors. I haven't done the calculations of the PSI at various heights, but I read someone had calculated it at 100,000 PSI at the end of the collapse.

Anyone who wasn't in the core and low down in the building (plaza or below) perhaps under a beam would likely get crushed.

I don't think that the 10-14 seconds of the collapse is unreasonably fast considering that the columns were not crushed in the collapse. The floors simply disconnected from their supports and or broke apart from the powerful avalanche of debris.

I think this is a gross oversimplification made primarily on "gut" feeling. Even if the buildings did not have a concrete core, which I believe the evidence shows they did (when properly interpreted and understood), the manner in which they came down shows the main resistance of supports beneath this "avalanche" was systematically removed to enable the "collapse" to proceed at near free-fall speeds. That was certainly shown to be the case with WTC7, as NIST has already conceded. It is clear to me that far more asymmetrical progression of damage would most certainly have been the result IF the primary supports from the intact structures below the "avalanche" had NOT been eliminated.


There are several things that we are too quick to dismiss or simply overlook in these events. One is the sheer volume of pulverized material that blanketed a very large portion of Manhattan to the tune of 3"-4" deep. I have seen controlled demolition films of buildings that were approximately 1/3 in size/volume to the twin towers and the dust clouds for those are FAR smaller in scope with regard to the progression of their dust clouds and the blanketing of dust left behind. Statements from 911Review.com and calculations from Jim Hoffman regarding the dust clouds and the possible energy requirements for creating such a phenomenon are very interesting. 911Review says:


I've watched many controlled demolition tapes and I just don't see the same voluminous amounts of dust in the typical KNOWN controlled demolition events. So, I am very much opposed to accept that gravity acting ALONE could account for yet an even LARGER degree of fine destruction and expulsion of materials than is normally witnessed in already known CD events. Stack it as high as you want...the energy from gravity alone just is NOT SUFFICIENT to accomplish what was done to those towers.






No, I do not agree that the slabs would "hardly survive" impact loading. Where EVER in the photos of 9/11 do you see even ONE sheet of corrugated steel decking? It's already pretty much FLAT...what else can be done to it in a gravitational event other than some shredding of some of the pieces and bending twisting? There were THOUSANDS of sheets of this stuff...

I'm no expert on pyroclastic flows, but I don't believe they are too difficult to understand. They are mainly associated with volcanic eruptions and high explosive events and are also called "pyroclastic density currents" (PDC's). They are generally lateral or downward flows of dense clouds of solid particulates suspended in turbulent hot gas clouds which move quickly away from the source of explosion or eruption. I do not believe a pyroclastic flow would ever occur in the absence of high explosives or a volcanic eruption if you just dropped a massive volume of fine material from 110 stories due to the absence of any source of hot gas to suspend the particulate mass. It is my understanding that a very large amount of thermal energy is involved to produce the conditions for this phenomenon.

The obvious presence of pryoclastic flows or PDC's on 9/11 for both the Twin Towers and for WTC7 are very conclusive signatures of the high energy explosive forces involved in their destruction. The rest of the details that people ceaselessly fight over are pretty much psyops window dressing to me. I think Dr. David Ray Griffin said it best..."“No building exhibiting all the characteristics of controlled demolition has never not been a controlled demolition."

Let me explain something which many people don't seem to understand about the structure and the collapse of the floors.

The floor slabs did not rest on columns. They were attached to the SIDES of the columns. The slabs were supported but trusses which were connected to every other facade column. They rested on steel angles welded to the inside of the spandrels and were bolted with 2 - 5/8" bolts to the angles. A similar connection was to a channel which was in tern welded to 28 beam stubs on to the 24 perimeter core columns.

So each floor had 110 connections to the facade 28 to the beam stubs (90 resting on the channels with the channels connected at 28 points to the core columns)

The collapse did not involve crushing or bucking of columns. The columns survived the avalanche. The avalanche "sheared off" the floors from the core columns, and ripped the trusses off their seats. The failure of the floors was shear - There was no resistance "below" the floors - they were on small beam seats noted above.

The dust which covered a portion of lower Manhattan was perhaps 2 inches thick and was from all the destruction that day - two huge sky scapers, and one have the size. The dust filled mostly the streets for about 8 blocks around the site. There are calculations of the volume of the dust.

There are two calculations - the first debris plume from crash of the top sections and the massive propagation at the end of the collapse. The first is very much like a standard CD of a 15-30 story building - that's what came down first. The latter was the result of a collapse much larger than any CD ever seen and involved the entire mass of the towers and the energy to grind them to largely fine grains - that produces a lot of heat. The first debris plume was about 500' diameter and did not grow wider - the debris then dropped straight down. The bottom cloud DID propagate outward very rapidly - faster than a man could run and it billowed up as well.

What sort of cloud would you expect if 500,000 tons of debris dropped from as much as 1200 feet in about 200 foot square?

Pyroclastic flow is not the correct term. This is more like a steep vertical avalanche which took place inside a tall square donut. It forced the facade columns outward and left the core columns standing.

DRG's statement is not a proof of anything. Many things can resemble something else and in this case I believe a sequence of explosions could resemble a collapse - or a collapse could be describe as a sequence of explosions.

The physics tells us what would happen when you drop a tremendous load on a 4" thick concrete slab. It fails.

i am astonished to read such nonsense after so many years.

the primary issue persists: why would any enemy of the great satan waste any time on attacking such irrelevant targets when real strategic targets were just a few more minutes away?

but ignoring that most salient of issues, how many stories high would you think the pile of debris should have been? and how high were they?

also, do you really think that a 767 with a relatively light load of kerosene hitting so high up on either one of the towers could have caused such a symmetrical structural failures] and also vacated the subfloors so that the debris pile was essentially contained within those subfloors?

and then there is the history of atta, shehi, and venice florida and the dutch boys. so remarkably ignored by virtually all the israeli-controlled media. told well by daniel hopsicker. these were no jihadis. and i doubt that they were even on the aircraft.

do you think that they were on these commercial airliners?

SanderO,

i see, what your saying,
when i swat a fly,
the flyswatter doesn't slow down at all.

...but 110 stories of flies?
...even with 96% air in between them?

and that's still the path of greatest resistance.

free fall speed, most of that energy would have been spent,
in the demolition of the concrete to dust.

Ever tried hammering a rock, down to dust,
especially using a smaller part of that same rock?

Concrete is a man-made rock.

Could someone tell us…how close to the point of impact did the building begin to collapse.

On another thread, these planes could have been “Special” KC-767A slightly tweaked.

Would it not be funny if they had hundreds of time delayed C-4 packets with-in them?

Aim for the core boys and let these little buggers do their job.

I am pretty much a believer in the inside job thesis. However, I believe the job did not involve the extensive explosive demolition that many do. I believe that the planners understood the structural vulnerabilities of the towers and knew that that could "fake" the collapse caused by planes with actually very few explosive and heat generating devices placed at around the intended strike zones. We need to focus on so many of the lies that were told and not become obsessed with the "illusion" and distraction of whether the collapses were natural or some complex series of explosions which blew the towers to bits.

NIST and FEMA don't really explain the collapse but offer bizarre fairy tales about what initiated them. Because they have "lied" and used false science critics simply discount every word in their reports. Since they didn't really go into what happened after initiation lots of what they do is convoluted logic to manipulate the facts around a foregone conclusion - planes and then the fires took them down.

The fact that the towers destruction was "symmetrical" is only significant of the form. And the destruction wasn't completely symmetrical regardless. The facade panels ranged from 230 feet on the south side of the south tower to 430 feet on the west side of the north tower. But the floor collapse was pretty much straight down as one would expect some of such mass to drop when there was no large asymmetrical forces applied. Even the tilting top's CoG was within the footprint and most of it came down inside the footprint, though some went over the SE corner for sure.

I keep debating about the factual nature of a gravitational collapse and little focus is on what caused the tops to actually tilt and drop. In the case of WTC 7, no one seems to dispute the fact that once the structure in the lower section of the building was made structurally invisible, gravity (free fall for 2.25 secs) took the tops down and they crushed themselves and turned largely to dust and fine material. I don't think any one is claiming that the WTC 7 debris was significantly different than the twin tower debris.

There were differences because 7 was a curtain wall and 1 and 2 had a load bearing shell (facade), but all the collapses had similar results. And that is what happens when hundreds of thousands of tons of material loses its support - it drops straight down and it crushes itself to granular size. This doesn't or wouldn't happen in a smaller building collapse.

In all three cases the CAUSE of the collapses is what is very suspicious in my opinion, not the actual collapses. It's fairly obvious that the plane strikes did not "knock the towers over" even though they might have damaged several columns. They didn't damage enough of them and so the towers stood. So NIST then says it was the subsequent fires that did it. But we know that the fires were no extensive enough, nor hot enough. So there HAD to have been other causes and that is the conspiracy.

I personally think that all who doubt the official account agree that there was some tinkering which initiated the collapses. I think the focus and debate should center on this, not on debating physics principles none of which were defied by the collapses. That in my belief is a distraction. The same with whether the core contain a concrete shell. This had no relevance to the floor collapse once the tops came off column.

In the end the simplest conspiracy would be the most reliable one to pull off and I would look for this.

The antenna started to drop first, on the tower with the antenna. (N. Tower)

http://www.youtube.com/watch?v=mDa94ADiiLA

like the central structure on the top of building 7, collapsed,
commencing that buildings demolition.

http://www.youtube.com/watch?v=5864an4_w6Q

Building 7 demolition, did not require a plane apparently.

And that makes one wonder if the towers,
only needed planes for the plausible deniability, of their demolition.

However, it seems to be the top center, that goes down first.

According to the NIST report -

WTC 1 failed at the 92nd floor. The impact zone was between the 94th and 97th floors. So the building failed two floors below the bottom of the impact zone.

Based on the videos, the antenna started to drop into the building before the floors began to fail. The impact zone was on the north side of the building, but the top of the building tilted to the east at the start of the collapse and most of the debris fell toward the Plaza side of the complex.



WTC 2 failed at the 81st floor. The impact zone was between the 78th to 84th floors. According to NIST, the collapse started because bolts that connected the trusses to the perimeter walls failed. Only problem, the 81st floor had beams instead of trusses holding most of it up. The impact zone was on the south side of the building, but the top of the building tilted to the east at the start of the collapse and most of the debris fell toward the Plaza side of the complex.

Tilting the buildings to the east made clean up so much easier and the streets that border the complex were relatively undamaged and were cleared by the next day.

i am still wondering, if there is and was something in the building code,
that says big buildings, in city cores, need an end-of-usefulness future demolition plan before being built.

I doubt it. It would cost too much money to do that for every building. In my somewhat limited experience, I've never come across such a thing. If there was some requirement for big buildings, it certainly wouldn't be a secret. Architects and engineers assume their projects will last forever and have little concern about what happens to them when they've reached the end of their usefulness. Demolishing a building is not that big a deal anyway. It just takes time and money because what goes up, will eventually come down one way or another.

However, it is a standard demolition practice to drop a building towards an open area like a parking lot or an open plaza whenever possible.

Actually, I must differ even with this small concession. We may not be able to perceive the deceleration of the flyswatter with our limited sensory perception, but even that fly presents a brief moment of resistance resulting in a measurable deceleration to the flyswatter's velocity, even if only a nanosecond....at least at the point of contact and likely resulting in a deformation of the flyswatter's lattice.

Strongly disagree....pyroclastic flow IS the correct term. This event was markedly and observably consistent with a high-energy gas expansion event which is far different than a simple dust cloud from a building that has experienced complete structural collapse unaided by explosives (of which I can't think of one ever happening prior to what the govt insists to have happened X3 on 9/11, btw...). If anything can resemble anything else, then what good is analysis and facts?

You keep talking about this "avalanche" as if it is the initiator of the destruction event. I don't disagree there was a growing avalanche of debris...but it was the effect, not the cause. I also think it is blatantly wrong to ignore the unreal amount of materials that simply pulverized "themselves" in mid-air. There is just NO energy....NO mechanism for this to happen. Concrete floors can't just pulverize themselves and eject themselves upwards and laterally from a DOWNWARD destruction sequence....not without a LOT of help. It is quite clear that a MASSIVE debris cloud was already forming in the first few milliseconds of the initiation of the destruction sequence of towers 1 and 2. The pyroclastic flow of material was not just pushed out from the force of the materials hitting the ground. There was the presence of enormous amounts of HEAT creating that very very unique phenomenon.

You are entitled to your theories and opinions just like we all are. I am glad to hear that you do consider the events to be "an inside job" and I see that you also consider that explosives must have been used in some amount and fashion. I think sometimes we need to focus on details and the facts correct between all our various perceptions of what we all see and hear, but we also need to agree to disagree on some specifics until we are able to get to the point of moving forward to securing a REAL investigation that WILL uncover what we do not yet know, confirm some of what we suspect to be true, and set the record straight on those points where we are incorrect. Either way, I can say with CALM assurance that we don't know it all.....yet. But we DO know enough to challenge the BULL we've been spoon-fed from our servant government "officials"...

I appreciate the thought you've obviously put into your theory and your calculations. You many not be far off the mark in some areas, but at this point I am not persuaded by the bulk of your arguments.

There is also the issue of the large volume and occurrence of molten metal at the bases of all three buildings. I cannot see ANY mechanism for this phenomenon other than explosive or incendiary intervention. There certainly is not enough kinetic energy in the fall of materials to create fine, micron level disintegration AND heat up steel to it's melting point....and KEEP it that hot for WEEKS. To me, this is a major signature and solid evidence for a thermite-induced eutectic process. The findings of the FEMA/BPAT investigation were very striking to me.
http://911research.wtc7.net/wtc/official/fema.html

I think the ground smoked and steamed for 3 months after the demolition,
with water poured on it.
That's a huge amount of residual dissipating energy.
i doubt if thermite alone, would be enough.

Also there was iron spheroids found in the dust,
if this was caused by condensed iron vapors,
then the iron must have boiled,
not just melted.
and that, is a higher temperature than can be achieved by the thermite reaction,
that can only liquefy iron, not boil it.

yes, Freshkills, quite right,
the single fly does slow my swat, a tiny amount.

(that was exactly the point i was trying to make.)

By the time the curtain wall that was attached to the top 25+ floors on the east side of WTC 2 started peeling away from the building, the interior contents had already been pulverized.

Some clarifications about my "theory".

The avalanche was the result of the dropping of the tops onto the bottom.

The lingering high temp are the tell tale signs that some very very high temperature reactions which may have not even required oxygen had or were taking place. This may have been associated with collapse initiation and don't seem to be the result of natural causes.

The key steps as I see it were as follows:

Plane strike

damages several columns, starts fires, dumps fuel into the building which likely traveled to other floors. Local damage to several floors. nothing is collapsing.

Pre collapse of tops

fire is spreading, liquid metal seen pouring out of south tower corner opposite plane strike and close the exit location of engine, smoke color changing, no noticeable motion in the building except some facade column distortion. This period is about an hour and a half for the north tower and half that for the south tower. No evidence of any collapse, no visual evidence of explosions

collapse begins

Both towers tops tilt to the south and east. The large 32 story top of wtc tilts as much as 20°. The first movement in WTC 1 is the ocillation and then dropping of the massive antenna mast supported by the hat truss. This indicates that some central core columns and perimeter core columns such as 503, 504, 701, 801,707, 808, 1003 & 1004 (some of them at least) have failed (buckled, been cut???) and are not supporting the mast.

The tilting is accompanied by a vertical descent of the top sections. We also see what appears to be ejection laterally of smoke, debris, fire and building materials at the collision zone of the tops and bottom. There is some indication of explosions at the initiation of the descent and material is hurled up to 200 feet. Where the top and bottom meet it appears that the top's bottom is disappearing. This is likely the top's floors dropping into the shell of the bottom and beginning to accumulated on the upper most bottom's floor. It is also likely that that floor and perhaps the one below are being broken in places by the collision with the bottom floor of the upper section. Both top and bottom's core columns are stabbing at the floor slabs, beams etc as they now longer align axially. The lower sections of the top's facade are breaking apart, falling in or and or outside the core and some are pushed by the compressed air of the collapse or the explosions. The tops are not in free fall and and their core structures are being torqued, twisted and connections broken until it can no longer maintain any integrity and it collapses like a house of cards... pouring almost all of the material onto the upper floors. The lower section's facade contain the collapsing floors and stand above it for several stories because of their staggered construction.

Avalanche begins

The mass which has broken apart from the upper sections now is crashing down and accumulating on the upper floors once the floor areas are seeing their yield strength passed and they break, drop, crumble and begin accelerating downward. Each floor slows the avalanche a bit, but each floor then becomes part of it and adds its mass. The avalanche reaches a terminal velocity of about 80 mph. As it moves down it forces the air outward and breaks all the glass and sends all the light material outward (explosively and) almost uniformly around the perimeter. Little or no signs of fire are seen in these ejections. "Squibs" are seen many stories below the collapse front. They might be material that had fallen into shafts and faced no floor resistance at all only to shoot out horizontally when they encountered the pit and the debris excited blasting the elevator doors out, and then following the corridors and then out a window which was aligned with the corridor. (this is a guess).

The facade peels off in huge sections as the floors which supported them laterally have broken apart plunged down. The facade falls away from the building in assemblies of multiple panels and the highest ones land up to 450' away from the towers. The debris cloud from the initiation event is descending at almost free fall, impeded by air resistance and out paces the avalanche and obscures it after a few seconds.

In about 10 seconds the avalanche is over, the destroyed, crushed, pulverized material, much of it is suspended in the air is carried away in all directions as high speed by a hot cloud of air, heated from the friction and the fires ( and the incendiaries). This cloud deposits up to 2" or more of fine dust for up to 6 blocks or so. The core columns are scattered about the footprint mostly with some lying outside. The facade panels are radiating from the buildings mostly and as far as 450' from the building. Many are in tack except for the mangled or ripped off truss seats.

The collapse draws in "new clean air" behind it where the building once stood. Now the NW window carries the lightest dust and smoke over lower manhattan and across the east river to brooklyn. The hot duct cloud is so dense that it blocks all light until it settles into the powder seen on everything in lower manhattan.

Yes, and looking at that photo you attached...I must ask, how does a near perfectly symmetrical "crush front", as Sander0 calls it, ring the building with such a leaning "crusher" ??

EDIT: A better wording is... How does such a leaning "crusher" create such a near perfectly symmetrical "crush front" around the building perimeter?

To me, there is just no way the upper block of 30 or so floors from the South Tower could have acted in the manner you state. The building's contents were clearly being pulverized way too early in the process. I understand that you are trying to make sense of the progression of how things happened in this event....we all are. One thing that is very indicative of the use of explosives (to me) is the fact that the upper block of floors on the South Tower did not fall as a consolidated block all the way to the ground. Its movement was halted and it disintegrated before hitting the ground. This is beyond amazing, or so I had thought. I just read this piece of information last night and find it very interesting. It explains a LOT about the South Tower block's amazing defiance of the laws of conservation of angular momentum... This is from a DRG site, so hopefully you won't discount it too much, Sander0.



Another facet of the destruction of both WTC1 & 2 is the massive separation of the outer facade into smaller chunks, many which were hurled laterally. The outer perimeter columns were amazingly interconnected with those wide spandrels. That whole facade was an amazingly strong interconnected lattice... How can something like that be literally torn to pieces with supposedly mainly downward forces (gravitational collapse) acting upon it? To disassemble that many intimate connections of steel would require some amazingly well focused LATERAL forces acting on that structure. Again, I can only see explosives performing this kind of work, not gravitational kinetics.

Damn good post FK!

Thanks Amazed!, I find DRG to be a huge asset to the quest for truth, and not just because he properly sources his research, but that certainly is to his credit.

Here is the DRG source for the Loizeaux quote:
50 Liz Else, “Baltimore Blasters,” New Scientist 183/2457 (July 24, 2004), 48 (http://www.911research.wtc7.net/mirrors/new_scientist/BaltimoreBlast_Loizeaux.html).

i think, i remember a description of a tower being a tube within a tube,
with both "tubes" being able to support themselves, separately.
To "bring down" such a structure into its' own footprint,
would require the center core (the inner-tube), to being "lowered" first.
The antenna drops first, and the top center, of building 7 does too.
If the perimeter walls, had began the demolition, and the core was left standing,
the towers could have fallen further from their foundations.

Sort of like creating a hole in the center, every thing else can "fall" into.
It makes me wonder, if the core of the towers was dropped a little with explosives
at their base. And each tower was built like 3 stacked separate buildings.
So, i'm guessing that the initiation of the collapse demolition was started inside, at the base of the top third, of each tower, at the core.
(pretty close to where the planes hit, curiously enough, i think.)

FK

If you study the vids of the north tower you can clearly see large "assemblies" of the 10x36 facade panels after they've "come off" the building. Some of these are 12 stories high (144' and up to 80' wide) 4 panels high x 8 panels wide. Several were obviously smaller assemblies.

Note in the video they are tipping over with no internal stress very much like what a tall wall would do or a flag pole. The top of the assembly is moving with more horizontal velocity than the bottom while the entire assembly descends at free fall acceleration. We can see the assembly become horizontal and it then continues to drop in a horizontal orientation until it hots the gound or in the case of the one cited the WFC.

For this to be "exploded off" the building, the explosion would have to exert a larger force at the top of the assembly which had enough force to dislodge it yet not break it apart. or there were explosions of decreasing force at each lower floor which went off at the same instant which also dislodged the panels yet not enough to distort this massive assembly which came off as a huge flat sheet.

What this ACTUALLY tells us (and you can see this in Chandler videos which he used to illustrate some his other theories) is that these huge sections were NOT exploded off the building and "ejected" at high speeds, but peel off and toppled over when the floors which held them laterally plumb were destroyed (by an avalanche - my theory).

Those who state that the facade was ejected explosively are not looking at the evidence in the videos. Further, the computed horizontal velocity based on the height they originated from and the distance they landed does not exceed 34 mph for any panel in the debris field. This is basic physics. 34 mph can be explained by the behavior of something toppling over... much like the top of a flag pole has a horizontal component as it fall over... and is displaced from its plan location by the height of the pole.

WTC 2 - the Tilting Top.

I believe that there was some "funny business" which caused the top to tilt and descend. This was associated with the destruction of columns on the SE side of the plan. With no support on the SE the rest of the building's column had to try to carry the load of the destroyed columns. This led to the NW side of the core to buckle under this enormous increased load. If there had been a "true" hinge point running though the interior of the structure from SW to NE, the NW corner would have risen as the SE corner dropped as the top tilted. IT DID NOT. The remaining columns to the NW of the instead of transferring loads down began to go into tension and the top of the tilting top on the NW side was supporting the floors below it. The hat truss was involved in this transfer of loads. And the structure was not in free fall and with no internal stresses. It was still transferring ALL the loads of the top in the remaining connected columns and in the collisions with the top of the bottom.

In a few seconds the stresses were completely exceeding spec for the connections of the upper tilting top. And when this happened it collapsed like a house of cards in a instant.

A thought experiment.

Take a 32 story building and lift it from the top? What would happen? It would collapse in an instant The columns structure is design for compression. The columns would stretch and break. The column splices will fail in shear in a instant.

Take a 32 story building and tilt it over onto one edge and "let go". What happens? Will it tilt over because the center of gravity is outside the foot print? It would were it a completely rigid block. It is not a rigid block, it is FRAME - a 3D grid and the connections will fail in SHEAR.

Can the edge of the 32 story building support it? No, it requires ALL the columns in the plan. What happens? All the connections of beams and columns will break the instant you let go and it will collapse like a house of card.

People can say they don't believe a building could disintegrate at the top of wtc 2. They simply do not understand statics and the design of steel structures, standard frame or hull and core. I have been trying to explain this to many in the truth movement who simply don't understand structure, statics and so forth. There is lots of resistance because they apparently want to believe that EVERYTHING in the collapses was the sign of CD. Most of it was natural. The cause was unnatural (CD) or engineered destruction of key elements. Once THAT was done, the building collapses were natural.

DRG is a great thinker and very logical does his research. But he is human and fallible and he doesn't understand structure and quotes others who be believes DO understand structures. And some of these referenced experts are wrong about some things. I have sent an email to DRG pointed out some questionable statements and explaining my logic. He responded that he was too busy at the time to look into what I wrote. That was perhaps 2 months ago.

Bazant, NIST, FEMA, AE911Truth all make mistakes. I make them, you make them and when we do, we need to step back, acknowledge the error and revise our position accordingly.

I began believing that everything was "CD" and then began to study the structures and re examine each and every claim made by the "truth movement". I found they made some errors... as did NIST etc. But the fact remains that the official story has TOO many inconsistencies and errors in the reports and we need a new investigation and it sure looks like there was "help" in getting those buildings to collapse (naturally).

I am an orphan of the truth movement having been active in AE911Truth even serving on their board for a while and found I disagree with some of their statements though I agree with their thrust to get a new investigation. I certainly don't support the 19 hijackers did it theory.

What you don't get SanderO, is that your courteous questions and observations are presented in a way which somehow suggests that the Official Story is actually correct and factual.

And that is an absurd proposal, all things considered.

I've long said that for the sake of argument, one could concede virtually any point within the OCT, and still prevail in the argument, for there are SO FOOKING MANY other points that do not fit like the towers collapse does not fit.

Amazed,

I respectfully disagree. I do not support the OCT - NIST explanation. Their report does not discuss the collapse, but it makes up some ridiculous non credible explanation as to what initiated it - heat from the fires.

The truth movement has rejected rightfully so, their collapse initiation fairy tale and then gone on to claim that the collapse itself was ALSO am explosive CD type destruction. I don't agree with NIST because they don't discuss the collapse. I disagree with the truth movement which DOES and claims it's CD. I say it was natural and agree with them that the initiation was UNNATURAL - call it CD if you will.

It is the initiation of the collapse of the twins where the lies are deception are taking place. I have several "scenarios" - speculation on what initiated the collapse and they DO INVOLVE explosives and incendiaries and not office fires.


My beef with the truth movement vis a vis the twin towers is that their reasoning about the collapse is flawed and they have not looked into how the structure might and DID fail and collapse naturally. They cling to reductionist and over simplified physics principles and refer to the building as being two blocks and expect the upper section (block) to act as a rigid block and tip over the side. This is completely showing a total lack of understanding of engineering and what was taking place.

If you trace the path of the NW side as it "tilts" you will see it also is descending. There is no fixed hinge position. Second, as it does tilt the lowest SE corner move NW INTO the building. If the hinge point were at or close to the SE corner then the NW corner would have to raise as it rotates about that hinge. Of course this didn't happen. The NE corner DOES NOT rise as it rotates when the upper section tilts. This is basic geometry. Essentially what was happening is that the NW columns held a bit, the SE ones were "disappeared" structurally and so the SE section of the top "dove" dove into the SE corner of the bottom... and continued to until the upper sections NW columns were buckled and not connected to the lower section. THEN the rotation slowed and the vertical descent increased and this caused the mutual destruction in a crush down crush up event and the upper section seems to collapse like a house of cards in a instant when its frame can't hold it together... without axial support on its columns or being in free fall and without internal stresses.

The truth movement wants people to believe that this instant was the instant of a massive explosion when it was turned to dust. That certainly would look like what happened, but it wasn't what happened.

And the same for the ensuing collapse. It could be a series of timed explosions proceeding down the tower IMITATING a collapse. But that would be wrong, in my judgment. It was a natural progressive structural failure. And this could be seen as a progressive top down CD... if you want. It wasn't.

The argument with the OCT is collapse initiation. They got that all wrong and I am 1000% with the truth movement there.

And this means, of course that the planes were "shock and awe" and a distraction from the "CD" to follow which would iniate the natural collapse. Apparently it was decided that the WTC had to be destroyed completely (for multiple reasons?) and the shock and awe of the strikes was not enough.

If the twins stood, they would have needed a third strike in WTC 7 but manufactured the absurd "reason" that debris from the collapse of WTC 1 caused those fires which again "initiated" wtc 7's collapse. We know that was hooey of course. WTC 7 was slated to go because in apparently were all sorts of records someone(s) wanted destroyed and collecting insurance claims etc. was a swell idea.

The collapse of WTC 7 is the clue to the fact that the planes were shock and awe and initiations were NOT fire caused.

Well, we are all entitled to our disagreements, of course, and we are all entitled to splitting hairs.

My guess is that the truth in the details will never be known.

Amazed,

We obviously can disagree over opinions and theories. But we can't disagree over the facts.

My efforts have been to establish the facts related to the structural failure of the twin towers in particular. Even before we look at the videos and the debris photos we need to understand structure, the twin towers in particular, and the how any complex composite structure will fail structurally. These are facts that there should be no "disagreements" about.

I see very little analysis from AE911Truth or other 9/11 truth advocates about the structure of the twin towers, ie how they could collapse, what were their vulnerabilities and so forth. Instead I read statements that there were "incredibly strong" and it was impossible for the them to collapse, impossible to collapse in 14 seconds, impossible to fall in or close to their own footprints and so forth. These are unqualified speculative statements.

There are some who are closely studying the video and trying to induce from them what happened. Chandler has done some excellent work, but he has made several mistakes in his analysis and conclusions. But that type of analysis will shed light on the details of what happened. And we can come away with some facts which there should be no disagreement on.

However, even agreeing on the facts of the structure, how it can fail (and all structure can fail) and what such a failure could look like seems to a barrier or hurdle which is muddying the waters in the search for truth and what CAUSED the buildings to fail and fall. And that cause I believe was unnatural and there was motive and so forth. But this is another matter.

The case to be made for a new investigation needs to focus on the cause not the collapse, in my opinion, because the collapses were natural and predictable failures based on the huge mass which was released and began to descend, but on how the collapsed were caused. The make a conservative case, with limited speculation puts the truth movement squarely in the realm of science when discussing the twin towers. Speculation leads to unproven theories and many scientists and engineers are no comfortable with this approach. And they are not comfortable with the work of NIST or FEMA either and so they have no "home" and probably are more concerned with the policy reversals than getting at the causes (perhaps).

In any case, considering that there are hundreds of thousands of architects and engineers and physicists and so forth, AE911Truth has only impressed a tiny percentage of them, something must be wrong. Admittedly AE911Truth focuses on the general public and draws its professional supporters in with BFT presentations. But they seem to be doing painfully little in real analysis using those professionals. Instead they cite their numbers and support of their basic CD message.

This is a complex technical and political problem and cool heads and rational minds must prevail or we will never get at the truth - the cause and who was behind the events of 9/11.

SanderO

We may be much closer to agreement than we think....

I understand your point about the "unnatural" aspects, and I also understand that you are a trained engineer of some sort, which I am not.

I'm not sure that counting the number of architects and engineers who have signed on at AE, as a percentage of the total count of that profession(s), is a meaningful way to assess what people think or believe. That, because many people are simply afraid to express their thoughts on this matter. My opinion is that a certain percentage of the population is UNABLE to come to terms with the truth inside their own heads, much less speak about it in public. My opinion is that certain inherent and internal defense mechanisms are at work.

Just like the population at large, there are many architects and engineers who would simply prefer to turn their pretty heads and walk away, if you get my drift.

I agree with you, and so do others that I have read here and there, that whoever the perps were on this "unnatural" destruction, they studied the building's unique structure and made meticulous plans as to how to "attack" the building for maximum and desired effect. They exploited the building's unique characteristics.

That is one possible explanation for the fact that the ACTUAL blueprints, original blueprints, are not to be found.

Because government agents were involved in this, there will be no more official investigations. I admire everybody's optimism and hope in this regard, but I know how the government operates well enough to say that THERE WILL BE NO MORE OFFICIAL INVESTIGATIONS.

There is and has been an OFFICIAL COVERUP, and the cards have been played.

The only investigation will be done by private interests and individuals. The govt has done its thing, and the case is closed.

Amazed,

I am an architect and my first job out of college was for Emery Roth & Sons who had just completed the twin towers! Of course this was an engineered destruction and whomever did the engineering clearly understood the structure and considered how to make the collapses look like they had come from the plane strikes and ensuing fires.

As important as it is to have the structural plans, specs, construction and test logs, we can actually REVERSE engineer the buildings from the architectural drawings we DO have and the films and stills of the construction. We actually know almost all we need to know about the structure at this point. We don't know the size of the lateral beams in the core, the type of steel they were, the design on the beam stubs and virtually nothing about the welds and column splices. We don't know the beams used to support the mechanical floors.

We do know the size and type of steel for all the columns, facade and core, the construction of the facade panels, the floor assembles, the floor trusses, the slab thickness. And we even know the specs of truss seats and the number of bolts used to connect the facade columns and spandrels. We know the specs for the windows and the aluminum cladding.

We can calculate the weight of the concrete (I have) and the weight of the columns. We even know the total weight of the facade panel steel. Engineers have calculated the total weight of the steel. We know the design live load, though we can only guess at the load of contents like furniture and equipment.

So we know much more than most think we know and certainly enough to understand the structure and its limits of performance. The structure is not as mysterious as you imply.

Understanding the collapse, and how to initiate it is not terribly complex. This is because the structure was so simple and actually quite vulnerable once some serious nasty stuff was done to it. Once the tops were "freed" from the columns holding them, the more or less straight down, almost free fall collapse was the ONLY outcome. That's my assessment as an architect of almost 40 yrs.

Could they have been constructed in the first place,
with a method of "collapsing" them in the future,
built into that design?
This could be why the original blueprints,
were "disappeared."

Lunk,

This is clearly a possibility, but I think rather a slim one. I suspect that getting those tops to drop may have involved the following principles:

Remove the support of a sufficient number of columns in the core. This can be accomplished in several ways and was probably done to something like 40% of the core columns or less. Each column has a "reserve" strength which meant that if one column were "removed" the remaining columns would be able to carry the increased loads. Removing a column can be accomplished by an explosion which blasts it laterally, a chemical attack which renders it to "a non loaded bearing member" of one that is able to support much less than its design load and so it buckles under load. A buckling column will pull down all the beams it supports and pull what those beams are connected with.

The 23 interior core columns carried much less load than the 24 core perimeter columns. But "dropping" the second rows from all sides would act to pull at the 24 perimeter columns. This would be rows 600 & 900 in the long core axis. These were all accessible from inside elevator shafts of the express elevators.

The key perimeter columns to attack would be 501, 508, 1001 and 1008 - the four courner. The columns alone carried about 1/3 of the floor loads outside the core.

Further the attack of the core needed to provide some "asymmetry" to facilitate the top sections above the "column attacks" to move off axis to enable the upper sections to drop. This could be accomplished by buckling columns on one side by the use of heat and severe overloading. You can't overload any of the columns unless you remove the load on some of the other columns. Could this have been done with delayed extreme heat which weakened columns on one side in advance? Possibly.

It's also possible that some of those 23 columns in the center were attacked way down in the structure. It doesn't matter were the force line is interrupted. If you "take out" a column on the 20th floor and make it severely "weakened" or structurally invisible, all columns above that columns "drop" and pull down all the beams (lateral support) which is connected to them. The antenna which preceded the collapse of the tops may likely indicate that several central core columns were "taken out". We can't know for sure at what floor and it may not matter.

As the key selected perimeter columns were rendered structurally below spec (weakening from heat or severing partially) the other columns now carried their loads. When enough key columns no longer were supported their axial loads what was above them began to drop as it was unsupported. This type of asymmetrical failure would lead to the tops sliding laterally as the dropped and even rotate as long as the moment connections of the top sections held the top "rigid and appearing as a "block".

The top would remain as a rigid appearing "block" if in free fall and or if the structure's moment connections were stiff and strong enough to not shear under increased loads.

Failure will occur when the steel passes its elastic limit. It remains intact, though elongated and distorted and weakened etc until the point that member's yeild strength is exceeded. Then it fails catastrophically. If you overload a column by adding weight it will buckle. As many have noted you can add weight but you could have and did have a load redistribution which resulted from the destruction of various key columns.

So in my judgment the destruction was engineered by selectively destroying the load carrying capacity of 40% of so of the perimeter core columns along with some of the center core columns. This destruction likely was not done simultaneously. It could have been, but the timing was not as important as much as removing enough core columns from their ability to carry axial loads and then having the remaining ones slowly go into overlaid status (exceed their ultimate yield strength). As this condition of overloading the remaining perimeter core columns progresses the structure reaches a point where the columns remaining undamaged can no longer support the loads - they are now trying to carry loads over their limit and they will buckle and the columns above and the structure they are connected to will drop. With asymmetrical removal, the upper columns will move laterally so that they are "free to drop" with no string columns to crush - but lateral beams and concrete slabs or simply no resistance if they plunge into a shaftway.

Once the upper section had moved out of column alignment the planned collapse would ensue as the floors in the lower section were now going to see the full load (weight) of the structure above. This came in two types of "impulses". One impulse to the lower structure was the columns above acting like concentrated loads punching through the slabs below and lateral beams like a hammer through a sheet of glass. The second impulse was the collision of the upper section's bottom slabs and the lower sections top slab. This was the accretion of mass that quickly built to an unstoppable avalanche as the floors simply were overloaded after 4 or 5 times their safe working load was exceeded. The destruction of the lower sections upper floor slabs left the facade columns with no lateral support.

It's conceivable that the facade could have stood (unstable) without the floors like a huge hollow tube. That would have been a real demolition nightmare for the clean up crews especially with a compromised core structure to work from (if it didn't collapse). So it's likely that some of the diagonal corner trusses which were 24' tall were attacked. This turned the tube to 4 planes - extremely thin (high aspect) and unstable. They would then be easily susceptible to small lateral force pushing them away and that force was supplied by the avalanche "debris" since as it pushed laterally as well as downward in its descent. The facade peeled off in large assemblies because there was little stress on the connections of one panel to the other. When they tipped too much the sheared or ripped the bolts holding the facade columns together and the same was true of the spandrel splices. The assembly size (peels off facade) was likely determined by the nature of the horizontal impulse from the avalanche.

The only "thing" left standing would be the core columns of the lower sections. This was seen in "the spire". They were also very very high aspect and would sway and oscillate breaking their splices and dropping like a vertical stack of dominos would. It's likely that some might have had some attacks of heat low down in the structure to ensure that they would drop down and not over as they would fall up to 1000 feet away. A few seconds after the avalanche has made it to the ground, it mass had also provided horizontal impulse to the base of the core columns and that might have been enough to shake them (their connections) loose and drop them.

The splice connections were meant to move, but not the way this event made them move and so they sheared and broke and the columns came apart in the 36' sections that made them up.

The above "scenario" is my "speculation" of how this collapse could have been initiated. One can go into more detail (speculation) about the specific columns which were targeted and how they might have been attacked.

i think the key here, is that each tower, was built in thirds.

So the initiation of the collapse,
must have started inside, at the core, near, or at, the bottom of the top third of each.
There probably were other specific areas taken out in preparation, for the demolition.

Well it's all very interesting, and plausible. I am still puzzled by the pulverized concrete.

In any event, it was executed brilliantly.

Sander0, I'm intrigued by your elaborate theories of the progression of the destruction of these buildings. Certainly, your experiences as an architect would afford you some special insights and I think this explains your desire to be as specific as possible in trying to understand what happened. For me, I am content to KNOW that a preponderance of evidence exists to show that a pre-planned, controlled demolition event (actually three separate such events) did in fact take place. I am quite comfortable with the amount of information we already have to support CD as a matter of FACT and no longer a matter of speculation. It is, therefore, not imperative for me to know the exact details of where the charges were actually placed and the other related fine details of the "job", although I find such information interesting and fascinating.

What bothers me most is that we have people running around who were in control of these crime scenes and, complicit or not, were directly responsible (and should be held legally accountable!) for the overt systematic removal and destruction of EVIDENCE from what is arguably THE LARGEST AND MOST IMPORTANT CRIME SCENE IN AMERICAN HISTORY (except perhaps Pearl Harbor). Whether these persons were a part of the overall conspiracy or NOT is almost irrelevant....the removal and destruction of evidence of a crime IS A CRIME!

I place primary blame first and foremost on Rudolph Giuliani as NYC mayor...however, I've recently learned from watching a Kevin Ryan video that apparently Richard Tomasetti of Thornton-Tomasetti Engineers and Michael Burton (along with other "officials" from NYC's Department of Design and Construction) also had input into "clearing" the decision to remove and ship off the WTC steel. While one might surmise that a few truckloads of steel could have been removed early in the process due to a gross "falling through the cracks" loss of control of the WTC destruction site, you just can't ignore the fact that there was protracted PUBLIC OUTCRY for this destruction of evidence to be HALTED for MONTHS...yet it continued without response from NYC officials. Where was the FBI? Where was FEMA? Who was SUPPOSED to be in charge? Surely SOMEONE woulda/coulda/shoulda halted this process!! But it just didn't happen. If this wasn't a DIRECT AND DELIBERATE attempt to hinder a major crime scene investigation and protect perpetrators, I don't know WHAT IS!!

To me, it's like when the 2nd plane hit the North Tower....from that point forward, there was NO QUESTION it was NO ACCIDENT.... Likewise...after MONTHS of public protest about destruction of evidence...there is NO WAY that it could be argued that it was just "an honest mistake"...or a breakdown in the chain of command...NO FREAKING WAY! The later, safely AFTER-the-fact....Tomasetti tries to pass off his part in "clearing" the steel haul-off operation by saying "had he known the direction that investigations into the collapses would take, he would have taken a different stand." Sorry, but I know the stench of BS when I smell it...nice try!

This is the part of 9/11 that I believe is still the most likely actionable....but time's a wastin' and "THEY" know it...

Here's the link to Kevin Ryan's video:
http://video.google.com/videoplay?docid=718236659434732032#

Link to info on Tomasetti and Burton:
http://www.historycommons.org/entity.jsp?e...ard_tomasetti_1

Here's a link to some very recent actions from NYCCAN along the lines I'm talking about here:
http://nyccan.org/join.php#instructions

This is my theory -
Highly pulverized concrete floor decks....highly pulverized office furnishings...missing floor pans...missing truss assemblies...missing intact human bodies...thousands of FRAGMENTS of bodies small enough to fit into a test tube = high explosives

Combine these phenomena with the presence of massive amounts of iron microspheres and unreacted nanothermite found in the WTC dust along with visual evidence that shows intense heat reactions in the form of obvious pyroclastic flowing clouds of dust/gases and the intense, odd melting of many vehicles near and around the base of the towers. Don't forget the large pools of molten metal found beneath all three downed WTC buildings that persisted for WEEKS. There was FAR more energy working at the WTC's than what could EVER be created merely from a gravity-only "collapse".

When we consider the pulverization or grinding of most of the material to very fine grains we need to compare and contrast the twin towers and WTC 7.

The truth movement and the OCT seem to agree that the top of the building collapsed down, likely from destruction of the structure on floors 7 -13. This was a CD collapse.

What was the nature of the debris of WTC 7? Was it the same "quality" as the twins? If not, what was the difference?

If it was substantially the same as the twins (no large slab sections or identifiable "objects" etc.) it would imply that the twins might have "collapsed" as well and a collapse of such mass can and will "pulverize" the contents.

This does not remove the explosives or heat which may have caused the collapses, but WTC 7 that clearly seems to be happening in the lower stories.

There is talk/discussion of WTC 7 falling at free fall and so this IS a collapse. To me this a type of "proof" that the twins collapsed as well. All three buildings left very similar debris. The twins of course had their core survive a bit and the facade peeled off and fell away whereas wtc 7 can pretty much straight down. All three had pulverized contents...and amalgamated heated compressed meteor like "rocks" created.

Breaking up concrete, to dust, and heat for months after, and free fall speed,
through the direction of greatest resistance?

And how many other skyscrapers have completely fallen,
into their own footprints, to heat before and since?

i think, the initiation of the demolitions of the towers could have been started anywhere within, and below the roof, in the top third, of each tower.
And that is where the planes collided (below the roof, in the top third of each tower)
Most people still don't know that building 7 was demolished hours later,
that same day, on another block, without a plane even.

(edit) clarification