http://www.rcac.purdue.edu/news/news_wtc.cfm

Wow, "pre determained conclusions". How can you accurately identified damage and weak points from a hypothetical computer model animation you created! It's going to show what you want it to show and do what you want it to do! I rather deal with open scientific debate and anlysis of the actual footagel. Cough*......not to mention they were government funded.

This simulation appears to be a fair hypothesis of the the impact damage caused to the tower by the airliner but is similar to the NIST report where they only attempt to describe events up to "collapse initiation".

If only they could do what nobody has done to date - use the airliner and fires to fully and convincingly simulate the actual collapse of the tower(s), ie symmetrically, top to bottom, at freefall speed. Now that would be really interesting.

As you appear not to understand how computer models are calibrated, perhaps I should supply my take:
The computer program itself embodies the laws of physics, how structures deform under load, all stuff that is used every day to design all sorts of structures. Nothing hypothetical there.
The input data includes the structural details of the building and the aircraft. Nothing hypothetical there either.
The aircraft speed, direction and impact point are from the available data on the day. Some slight adjustments possible because of uncertainties of measurement, but not much hypothetical.
The computer output includes stuff that can be compared with available data, like the size and shape of the hole in the side of the building, the way the debris came out the other side, where that debris landed. If this matches, then it is fair to say that what cannot be matched - the details of what happened inside the building - is likely to be correct too.
The animation merely makes the computer results intelligible to people without an engineering education.

My concern with the nist report is just how many flat out assumptions it makes regarding evidence. Such a small percentage of the debris was actually tested so I don't see with the assumptions and the lack of actual evidence to back up the claims how this can be anything other than just a demonstration that was absolutely predetermined; it doesn't seem to add much that is new to the discussion.

When a plane crash is investigated by the NTSB all of the debris is brought together that can be found and the planes are really re-assembled in order to find a cause of the crash; it isn't until everything is gone over with a fine tooth comb that they can make determinations as to cause. Somehow with nearly all of the debris getting trucked off right away there was an ability to not look at the evidence and yet come up with firm conclusions.

The nist report is flawed in regards to the fire effects on the steel supports...after looking at the report and the dozens of videos what they claim was not happening. As a firefighter that is all I can really attest to, but the bottom line for me is that the report is flawed and makes a lot of assumptions and just flat out seems wrong, but there really will never be able to be any more of a detailed examination of the evidence as it has been shipped of somewhere to be melted down.

Something isnt right, but I doubt we will ever know the truth.

This is far more difficult to model than the initial impact. It's basically a chaos theory situation: the outcome can vary a lot with small changes to the initial conditions, and the initial conditions are themselves not measurable for locations inside the building. How the fire spread would have depended on what sources of infamable materials were present in the offices on the day, details that depend on how the fuel was splashed around by the office fittings that were present. The temperatures reached by the steelwork would again depend on exact details of where the insulation was damaged and where it remained intact.

However, the NIST fire models show temperatures varying enormously across each floor, and it is reasonable to deduce that the differential thermal stresses that this put on the steelwork would cause further breakages. Again, though details are not available, a break in one point might not be significant, but a break elsewhere could be the final straw for a neighbouring beam, which in turn could overload the next one and start a complete collapse. Once the top of the building started to move, no engineer would expect any other outcome than the observed total collapse, or would find anything suspicious in lower story windows blowing out, how fast the building fell, or any other of the "anomalies" put forward to cast suspicion.

I'm not saying I know who was or was not responsible, just that looking at the collapse of the buildings is not going to get you any evidence for an inside job.

Flyingswan, I see what you mean about delving into chaos theory with all the possibilities available. What I am looking for though is not necessarily the exact way that the buildings did fall that day, just a possible way they could have fallen based on only the airliners and fires. If you are correct that…



… then it should not be difficult for someone to produce a reasonable simulation of how this could occur.

Unfortunately, one of the best attempts I have seen so far is the NOVA pancake collapse simulation which overlooks the small (or perhaps rather large) issue of the internal and external support columns plus each floor's connection with them.

Maybe the reason we have no credible explanation/simulation of the building collapes is that, short of adding explosive/cutting charges to the equation, nobody is able to pull it off?

right you are. There is no way on earth to explain the complete evaporation of those massive inner support columns at freefall speed of gravity.
If this were at all plausible, the designers and approvers of the design would have been prosecuted long ago for incompetence.
The fact is that no one is allowed to build projects of that scale that are supposedl, allegedly , this flimsy under relatively minor damage conditions.
If these solid steel-framed cages responded in this way to the impact of an aluminum skinned dart that burned cool enough for a woman to stand in the window nearby,
how in the hell were they were expected to withstand the potential earthquakes and hurricanes and fires that go into consideration for the design of every building?
Another thing, since the WTC complex was such a freakishly huge monstrosity of engineering in its day, can you even imagine for a second how much scrutiny
for safety the design would have attracted? It was THE MODEL of the architectural world. We are supposed to think no one was looking when this pathetic building
was designed to evaporate into dust should a plane hit it? THE ENTIRE WORLD WAS WATCHING this project , from beginning to end. LOL
It does not make sense.

The intellectually lazy turn a blind eye to the facts and assume that this is another 'Titanic' story, with some hidden edifying message to mankind of how the excesses of the rich can be folly, how man can over-reach his capacity and fall due to pride, etc. The people who planned the WTC demolition knew that it would be received by a soap-opera addicted , heavily medicated and obese America as whatever the Illuminati told them it was. The WTC was allegedly another Titanic, a massive monument to the self-indulgence of the rich which somehow deserved its fate, brought down by the weight of its own self-indulgent grandiosity. What a pile of b.s.
If incidents like the Titanic taught the engineering community anything, it was that when someone wants to build something massive that is going to hold a lot of people, you better take a close at the plans before you let them build it, and that is exactly what was done with the construction of the WTC.

On the contrary, there are plenty of engineering articles that find nothing suspicious in the speed at which the towers fell. Here's an example:
http://www.civil.usyd.edu.au/wtc.shtml

If you think that a building is designed to withstand the sort of loads generated by a block of a dozen or so storeys dropping on to it, please provide your evidence. And an airliner flying into a building at cruise speed, destroying 25% of the supporting beams at that location, does not constitute "relatively minor damage conditions".

yes it does. Modern skyscrapers are designed to withstand far greater stresses than that. The design of the World Trade Center, due its height and prominence,
was especially strong.

Because of the height of the WTC project, potential airplane impacts were a big consideration that went into the design and approval and safety specifications of the
entire project, as was fire safety . The building was designed as a heavy steel cage , it was not made of tooth picks. It is physically impossible for a metal cage construction
of welded steel to simply 'collapse' into fragments under the minor weight load of the small portion of upper floors. Especially the North Tower, where the impact was high on
the top of the tower , with very little weight. Think of the North tower as similar to a bird cage with a solid steel and concrete core standing in the center of it.
Try stamping on top of a bird cage sometime. It is not going to shatter. It might deform, flatten. THen put a solid rod of concrete and steel in the center of the bird cage
and try stamping on top of it. Try heating it and dropping a fridge on top of it . It is not going to shatter into toothpicks the way the tower did.
They do not design buildings to shatter like that, and they never collapse or burn down .


BUILDINGS ARE NOT DESIGNED THAT FLIMSILY. The World Trade Center 'bird cages' were sliced with cutting charges and then blasted to smithereens with either demolition
charges or some other weapon or a combination thereof.

Buildings are designed to support the static load of their upper stories, with a safety factor. The dynamic load produced by the upper stories falling only a few metres far exceeds this design load. If you don't believe me, ask the structural engineering dept. at your local university.

The aircraft impact design case for the WTC was a 707, postulated as lost in fog, flying at approach speed. The actual impacts were slightly larger 767s at cruise speed. That meant about ten times the aircraft kinetic energy available to cause building damage compared with the design case.

Try fitting a few small fireworks to your birdcage. Bang! If it isn't completely destroyed does that mean the CD theory is wrong? When you've done that look up the use of similarity laws in structural modelling.

So the whole official story argument basically rests on the fact that the planes were going faster than usual? The speed of the aircraft is supposedly the difference between
a building standing or exploding into volcanic dust and coating the entire harbor?

And this explains everything, including the mysterious underground fire that burned for weeks afterward beneath the rubble?

The central core should have and would have been left standing if the 'pancake collapse' theory were true. According to that theory the floors slipped down along the central core column.
There is no explanation for why the central support core came down, or why the building virtually exploded into dust in a fraction of the time it would have taken
for a structural pancake collapse to occur.

The official story is just not true. No amount of deception can conceal the truth.

I LOVE YOU! Gr8 post. Your being fair and rational.


LoL, right on mate. But here is the keyword "explode"; buildings falling naturally through a gravity driven collapse DO NOT EXPLODE, nor do they fall vertically dead centered straight down! That's why we have controlled demolitions; that is the aim of controlled demolitions, to bring a building straight down, unto it's own footprint with little to no resitance, that's why they use explosives, to get rid of the resistance which will allows the building to fall rapidly eliminating restricting mass. Good post.

Yes, ten times the design impact energy does make a difference. A load much higher than design will bring down the central core as well as the rest of the building.

In case you hadn't noticed, 9/11 was unprecedented. No-one considered it likely before the event, so no buildings were designed to cope with it.

If you think the towers shouldn't have fallen down the way they did, and the world's structural engineers think otherwise, the burden of proof is on you to support your case. With detailed calculations.

You don't even have to melt the steel. All you have to do is heat it up to the point that it expands past the limit which the fasteners can hold. When you do that the structure is sufficiently weakened to allow for a collapse.

You go straight from discussing 'impact energy' to 'a load much higher than design' bringing down the central core.
Make up your mind, either you are discussing the impact or the load . The load was not that much larger ,
the planes very similar in size.

None of the simulations have yet explained how the central core would have been brought down during a 'pancake collapse',
or how by some miracle all three of the buildings fell perfectly vertically. ONe of the television computure simulations even conveniently left out the
fact that there was central support core at all.

In viewing films of the planned demolition of the WTC , it looks like the top of the South Tower began to topple sideways ,
and at that point the entire building was detonated, including the toppling upper portion, and all of it exploded into dust.






'The world's structural engineers' are not in unanimous agreement on this, despite whatever the controlled and centrally owned press bleats.
There is also peer pressure to conform that permeates 'the professions', little things to consider such as whether you will ever work again in
your chosen field should you rock the boat, that kind of thing.

Pudue University in West Lafayette is an areospace technology and engineering school. Students, faculty and coalition focus/study groups are constantly running hypothetical scenerios, models, simulations and experiments in all facets of said genres. This article was posted originally in The Exponent, the Purdue University student newspaper, as ulumni, students, faculty and area professionals are usualy interested in the latest studies being conducted there. The study is one of thousands that take place at the campus each semester and while my Alma Mater is highly respected in many fields it is what is, a study.


Ahem. Go Boilers!!

The impact of the aircraft was ten times the design kinetic energy. The top of the building falling on to the lower part was 'a load much higher than design'.

"Pancake collapse" is a gross oversimplification of a complex collapse that no-one has simulated in detail. See above for the reasons. The core at the impact level was damaged by the impact and the lower parts collapsed when the upper parts fell on them. Buildings fall vertically because of the direction in which gravity acts.

It doesn't look like the entire building was detonated to me. The bottom storeys remained intact until hit by the falling upper storeys, at which point thay collapsed in sequence because they were overloaded.
Name the engineers who have published analysis that conflicts with a collapse due to impact and fire damage. What "peer pressure" is going to affect, say, a Chinese engineer?