The 9/11 Forum

It is all a problem of formulating the problem in the correct way as far as I am concerned.

My hypothesis is that the rigidity is not required to effect complete collapse.

That is the alternative explanation:

In my terms there would be a portion of the block which is rigid. The fact that this portion would keep getting smaller would not be a problem in my terminology: | | -> |

So you can ignore that portion.

Then there would be another portion that would be deforming /.

So you would have ejecta and deforming block and deforming building all at the same time.

The "magic number" would then be a block that would finish deforming just as the nothing more is ejected and there is nothing much left of the building to destroy.

If you imagine a non-deforming block that is large enough to destroy the building by weight alone if it were placed at the top. There must be something left at the bottom which represents that block since there is nothing much left of the building.

Take whatever IS there, and subtract it from that block. The remainder is the extra "unexplained" energy that is needed.

Otherwise you can ask what the chance was of such a block spontaneously disintegrating through quantum forces alone.

On the particles, I offer this:

henry-couannier-vs-greening-concrete-pulverization-calcs-t298.html#p7812

Ah yes!

So you need to estimate the average density of the material in the building set the hardness to a level where it can survive the fall (but not the stopping).

Then see how much damage, at a minimum is done by the stopping.

Work out how much material was left in the footprint, subtract from how much you need. and then find out how much additional cracking you need to get the object to break into particles able to be carried by the wind.

It is the energy component represented by that additional cracking that is the interesting part.

The trick is that there is no actual block that ever corresponds physically to what one needs, so it is a guestimation process.

I suppose next you are going to tell me to get to it then aren't you?

Darkwing wrote:In my terms there would be a portion of the block which is rigid. The fact that this portion would keep getting smaller would not be a problem in my terminology: | | -> |

I'm with you there. Eroded, but not disintegrated immediately. There is some evidence that was not the case, though. Looks pretty Fu'd quite quickly, hard to say what was left after a few seconds.

Take whatever IS there, and subtract it from that block. The remainder is the extra "unexplained" energy that is needed.

This point is going to take some work. But maybe the rift is not as great as it seemed. Too much to tackle now. There is plenty of energy to do this from PE alone, I don't expect you to take my word for it but I'm soundly convinced. If you want to pursue the energy end of it, I'd recommend the energy rate of change over time, the exchange between PE, KE and dissipated energy - units of POWER. Still, I don't think there's anything to be had there.

When you think back to my stick figure like this:

/\________________________________

that long line essentially represents the average profile of the resistive force; the bump to fail a story in the beginning chews up a lot less than gained from dropping - you know, give or take a little comminution and gas expulsion. Bazant calculated the energy required for full rotation hinge buckling (calcs maybe not super accurate but ballpark) - this did not happen according to observations of debris. Ergo, all that energy not consumed as per his model. That's a shitload of energy. It's hard to make up for that, in itself, with chemical explosives. Of course, they can be strategically leveraged, and that makes direct joule-for-joule comparison pretty much meaningless.

Darkwing wrote:I suppose next you are going to tell me to get to it then aren't you?

Haha, well if you're a particularly efficient computation engine, we might all get to go home a little early.

There is plenty of energy to do this from PE alone, I don't expect you to take my word for it but I'm soundly convinced.

Remember, the block has already been surviving the crushing process. So you need to work outwhat it's velocity would be falling through the underlying material.

When you think back to my stick figure like this:

/\________________________________

that long line essentially represents the average profile of the resistive force; the bump to fail a story in the beginning chews up a lot less than gained from dropping - you know, give or take a little comminution and gas expulsion.

Let me just explain my requirement that the block be large enough to achieve this WITHOUT being dropped: This is the only way that the block can be large enough that the energy required to push it off course would be smaller than the energy required to go straight down.

I think this is absolutely crucial in the whole thing. Without this requirement the block can be quite small.

This is the single most important feature of this block imo. If it were any smaller it wouldn't crush the building all the way down.

You COULD do it with an initial drop too, but we are already accounting for the end velocity and the terminal velocity at a another point in the equation and since these are derived from the initial velocity plus the density of the lower building we can't use those again. Doing it my way allows you to treat the drop distance plus the initial jolt as a single term already expressed as mass.

Bazant calculated the energy required for full rotation hinge buckling (calcs maybe not super accurate but ballpark) - this did not happen according to observations of debris. Ergo, all that energy not consumed as per his model. That's a shitload of energy. It's hard to make up for that, in itself, with chemical explosives. Of course, they can be strategically leveraged, and that makes direct joule-for-joule comparison pretty much meaningless.

It would be enormously large if it was just spread haphazardly through the building.

So large that it is almost redundant to do the calculation in the first place.

But if you assume it was deliberately placed...

Making the mona lisa from random paint drops is exceedingly unlikely, yet I know a guy who can whip you up a copy in a couple of hours for a couple of bucks. Actually I'm lying, I don't. But you get the point.

Haha, well if you're a particularly efficient computation engine, we might all get to go home a little early.

Unfortunately my computation engine runs on pure distilled essence of coffee and beer, global supplies are running low at the moment I fear.

That's why I say this is a wicked problem though, once you understand how to formulate it properly you already have the answer, but its bl**dy hard to formulate properly.

Conceptually, at least, a single low energy event can cascade through a stable structure and destroy it, if that event is enough to destabilize a part of the structure and cause another structural element to be then stressed and fail and then another one to be overstressed and fail and so on.

In the case of a structure which is storing gravitational energy such as a building a progression of failures through the structure driven by the release of gravitational energy is possible if the safety factors do not permit the structure to remain standing with some of its structure gone.

You can likewise set up a row of dominos of increasing size and tip the first one and a few seconds later tip one 100 times the mass of he first and of course all the other 99 before that. One small lateral push with the help of stored gravitational energy toppled all that mass.

The destruction or the twin towers was enabled by the weakest link being over loaded and this weakest link happens to occur on the connection of the floor system to the columns which support them. Once enough floors were released from the supporting columns at the top and assembled as a mass on a single intact floor and this load exceeded the weakest link ... the connection of that floor to the columns it collapse and the domino effect was set off, only in the case of the vertical collapse of the floor system, the domino which was doing the toppling grew more and more massive as the progression proceeded.

There was no need to beef up the floor connections lower in the towers only beef up the columns which carried the cumulative loads of everything above bearing down on them. So the trick to destruction was releasing enough mass to start the progressive destruction of the floors by over loading.

Most of the truth movement seems to assume the structure being strong as you descend needed to have explosives to destroy the columns to enable it all to drop like a CD or even have explosions proceed top to bottom to mimic a progressive collapse. They ignore the way the floors were connected.

The truth movement will see the panels flying off as the result of explosions in the interior and cite high speeds as proof. Yet none of the facade panels is moving at the speeds they claim and they all appear to be toppling over from vertical to horizontal not spinning and rotating and certainly not distorted as if some massive explosion sent these panels flying from the facade. And we can see some assemblies of them perfectly flat of 10 or 20 panels weighing 50- 100 tons toppling over. How could they be exploded out and remain intact?

The truth movement sees the blasts occurring all around the facade as the collapse begins and explosions all around the building, exploding the floors yet no panels are seen blown off only ejected through the windows. This is likely from air being forced out but the floor which is at the collapse front. What else would a floor collapse constrained by those facade panels look like? Nothing would be forced out the windows?

The question is what was the mechanism to get all that floor mass going down. If the columns survived the crash and were able to redistribute the loads there was no reason for the floors to be over loaded. If enough columns were taken out by the plane strike perhaps the others would be overloaded and begin buckle and then fail and cause the floors to crash and being a progressive collapse.

Or could the columns of the core perimeter and the facade be weakened enough by fires to buckle and start the progression of tumbling floors when the floors crashed into one another and destroyed themselves and the mass accretion at the crush zone began?

In WTC 1 the top section lost it support and began to plunge down. This led to mass accumulation of the uppermost undamaged floor on the bottom section which failed and the collapse of the floors was on. So the question is how did enough columns get displaced at the crash zone to enable them to drop as they clearly must have done? Without the columns being displaced, the floors would not be forced into collisions.

The NIST myth would have us believe that the trusses sagged and pulled in the facade columns. But what would that have actually looked like if it happened? Lets instantaneously slice through a staggered set of facade columns and take them away magically.

The 3 floors they supported would have no support on the facade side and be cantilevered from the core. Their core side connections would fail and they would drop. Three floors would drop down to the one below. Assuming it was overwhelmed it would then drop and the progressive collapse would ensue. But this would simply strip the floors from the core and the core would remain standing as the floors collapsed down and the facade either fell away or remained as a hollowed tube.

Destruction of the facade needs to be made to destroy the core. Call in the hat truss. The fiction here is that without the facade (sliced as noted above) the hat truss and the facade connected to it are now working differently. The facade which was supporting the hat truss is not being hung from it and the hat truss is acting like a boom crane boom and the facades the counter weight and the object lifted with the core being the central truss tower of the crane.

Now the core is hat truss is effectively carrying the facade and a substantial (half?) the floor loads and all of this is transferred to the core columns. So with the helpful hat truss the core now supports the entire load of the section about the severed facade. Let's assume the hat truss would not crush and it put all those loads on the core columns and they were now carrying 2 x their former load from the severed section up. Is it likely that they these columns would buckle if their loads was doubled when safety factors as high as 5 are part of high rise column design?

And were are all the buckled columns from up top? The observations shows almost all straight columns broken free at the their splices not buckled from overloading.

Something managed to get the columns up there at the crash zone out of alignment and plunging downward. What was it?

Conceptually, at least, a single low energy event can cascade through a stable structure and destroy it, if that event is enough to destabilize a part of the structure and cause another structural element to be then stressed and fail and then another one to be overstressed and fail and so on.

Yes, but it is usually unlikely to happen naturally in a way that goes through the path of most resistance.

The avalanche/domino examples are not really going through that path, the collapse progression just happens to go through the path of least resistance for each element. The dominoes, after all, prefer falling sideways. The fact that the collapse is going sideways is to their liking.

Tall buildings, on the other hand, are expressly designed to NOT like falling down.

ROOSD shows one way that that can be made to change, but the impossible condition required to initiate it is the key to understanding what it means.

In the case of a structure which is storing gravitational energy such as a building a progression of failures through the structure driven by the release of gravitational energy is possible if the safety factors do not permit the structure to remain standing with some of its structure gone.

That's what happens in those verinage examples. But again, these events are rigged to weaken the crucial elements beforehand. I think everybody is satisfied that that was not the case for WTC.

The underlying structure still had enormous redundancy.

The destruction or the twin towers was enabled by the weakest link being over loaded and this weakest link happens to occur on the connection of the floor system to the columns which support them.

I would contend the opposite in this case, but it is something that is very amenable to testing.

How these floor elements behave in situ under collapse conditions is a big issue.

Even so, if it is the wall connections failing you still have to explain the shattering of the concrete and exterior columns: most did not come off as large chunks but were dismembered element by element. The high energy ejections argue against this interpretation.

There was no need to beef up the floor connections lower in the towers only beef up the columns which carried the cumulative loads of everything above bearing down on them.

That is an excellent point, but it has problems in explaining the destruction of the facade and the crushing of the concrete.

If the wall connections were strong enough while these two things happened, why then did they suddenly fail afterwards. Why if they provide the resistance to the pancaking sufficient in size to allow the concrete to be crushed and perimeter to be shattered do we not see a judderry-stuttering collapse?

If the concrete was so light-weight as to become powder at the merest provocation, how is it supplying the mass needed to overcome the wall connections, surely the steel could not be made to behave coherently so quickly.

The truth movement sees the blasts occurring all around the facade as the collapse begins and explosions all around the building, exploding the floors yet no panels are seen blown off only ejected through the windows.

I would have to disagree with you there.

Personally it doesn't matter to me where any explosives were placed if they were placed, but I believe Achimspok would want to have a word with you about that particular assertion.

If enough columns were taken out by the plane strike perhaps the others would be overloaded and begin buckle and then fail and cause the floors to crash and being a progressive collapse.

I think that all parties agree that could not have been the case. Anyway, the initial tilt before the failure suggests a fulcrum at the far perimeter.

The 3 floors they supported would have no support on the facade side and be cantilevered from the core. Their core side connections would fail and they would drop. Three floors would drop down to the one below. But this would simply strip the floors from the core and the core would remain standing as the floors collapsed down and the facade either fell away or remained as a hollowed tube.

Much of the core did it fact remain standing for a while in one of the towers.

But this only really makes sense if you take a 1-dimensional slice. In 2-dimensions you can see the thing becomes asymmetrical very quickly. Once one side of the building fails the material will aggregate towards that side.

The symmetry-asymmetry problem is one of the biggest problems in my mind, because it forces you to accept Bazant's solid block to get the collapse to go all the way to the bottom all around the core.

The facade which was supporting the hat truss is not being hung from it and the hat truss is acting like a boom crane boom and the facades the counter weight and the object lifted with the core being the central truss tower of the crane.

That is why NIST stipulates core failure as the initiation event, Femr can tell us if that matches observation.

Again, the problem is going to be accommodating the tilt into this picture though.

Something managed to get the columns up there at the crash zone out of alignment and plunging downward. What was it?

That is the problem, they were never out of alignment as the ROOSD scenario requires. The tilt means that even though that scenario is the most likely with the step-out initiation, the step-out initiation is completely irreconcilable with observation.

To the extent that ROOSD tells you what would be required for a natural collapse to have occurred it also reductio ad absurdum tells you that it could not have occurred.

To be fair ROOSD doesn't claim to be the only possible natural collapse scenario, but I have yet to see anyone propose anything better.



I am of the opinion though that, ironically, it is Bazant himself who manages to rule out any natural collapse scenario positively.

I should've said this thread needs to be moved to other technical issues.

That is the problem, they were never out of alignment as the ROOSD scenario requires. The tilt means that even though that scenario is the most likely with the step-out initiation, the step-out initiation is completely irreconcilable with observation.

I caution against a rush to judgement based on an artificially constrained set of choices. As you pointed out earlier, there is no real drop. Columns did not disappear, they failed. Failure, no matter the cause, will have an influence on the geometric arrangement of members and also the degree of deformation of failing members. Maintaining alignment and plumb necessary to achieve rated capacity (near if not optimal as built) once substantial deformation (e.g. tilt) occurs is essentially impossible, the only question then is how much the capacity is reduced. Bending and buckling at initiation were observed directly in WTC2 and perimeter misalignment observed in both towers after initiation.

ROOSD is a collapse progression model. It is not meant to deal with collapse initiation or or tilt.

The fundamental question is: If certain conditions are reached, is ROOSD possible?

I introduce some basic principles involved with initiation, such as perimeter stripping, but the focus is clearly on ROOSD, not how ROOSD conditions are created.


In all honesty, I introduced the OOS idea originally to silence people who take the arguments in Bazant and Verdure and rigid upper blocks too seriously. I reintroduce it because many truthers seem to repeat that natural progression is physically impossible and a whole bunch of crap about the "path of most resistance", blah, blah....

Personally, I am just tired of hearing false and misleading arguments repeated over and over again.


I am not interested in the details of collapse initiation is this paper because it will be dealt with in another paper, the outline of which you can read in the OPs of this thread:
http://www.the911forum.freeforums.org/early-movement-of-wtc1-made-simple-t346.html

When people talk of the upper block "tilting", or a rigid block, or a hinge, I know they have not read or understood much of the new data achimspok has been taking, which is presented at the link above.

That issue is best dealt with separately in a paper which focuses on only that.

Maintaining alignment and plumb necessary to achieve rated capacity (near if not optimal as built) once substantial deformation (e.g. tilt) occurs is essentially impossible, the only question then is how much the capacity is reduced.

My feeling about this is that the two constraints work against each other.

I accept your point about plumb, but would it not be the case that the further from plumb you move the less likely a complete collapse is to occur precisely because of the geometric arrangement?

I liken it to trying to crush a candle from above with your hand. If you are exactly plumb it will crush all the way down, leaving a circle of wax at the bottom. But if you are even slitghtly off plumb or the candle is not uniform it will spit out. It will snap at the first opportunity.

Snapping candles is analogous to the top falling off. The more off plumb the failure was the quicker it will happen.This is different from a domino case where the collapse progresses in the direction in which the remaining elements are least stable.

If the WTC buildings were least stable in the face of lateral forces, we would expect the progression to favor moving laterally, i.e. off the building.

In all honesty, I introduced the OOS idea originally to silence people who take the arguments in Bazant and Verdure and rigid upper blocks too seriously.

There is no block, it is a mathematical fiction to describe all the forces acting on the building.

But 1) there must be some sort of physical analogue to it and 2) Bazant likely introduced it because he knew it was the only way to make the building crush all the way down.

the "path of most resistance", blah, blah....

The path of least resistance is as close to a fundamental property of space and time as you are likely to get. You can use it in almost every field in some way, from Macro-Economics to Particle Physics. "Blah, blah..." misses the point.

When people talk of the upper block "tilting", or a rigid block, or a hinge, I know they have not read or understood much of the new data achimspok has been taking, which is presented at the link above.

The point made in the Jaynes article (which seems to be my hobby horse now, hi-ho silver) is this:

E. T. Jaynes (1957) Information theory and statistical mechanics, Physical Review 106:620

"Phenomena in which the predictions of statistical mechanics are well verified experimentally are always those in which our probability distributions, for the macroscopic quantities actually measured, have enormously sharp peaks. But the process of maximum-entropy inference is one in which we choose the broadest possible probability distribution over the microscopic states, compatible with the with the initial data." (p. 627, author's italics)

In other words: If it smells like a mule, it sounds like mule, sounds like a mule and kicks like a mule we likely need not perform DNA analysis to determine if it is a mule. Its probably a mule.

If all that we need to know is whether this is a mule or a dolphin, I believe that further observation is not going to be all that illuminating one way or the other and endless argument about whether the hat-truss was hither or thither is unlikely in the extreme to influence the outcome.

Much more interesting is the behavior of specific elements like the floor assemblies and perimeter columns during the actual event.

The path of least resistance is as close to a fundamental property of space and time as you are likely to get. You can use it in almost every field in some way, from Macro-Economics to Particle Physics. "Blah, blah..." misses the point.

The path of most resistance, that is claimed on the home page of the AE911T website.

Passing false arguments off as proof of demolition does not help the 911 truth movement.

You should read more of the forum before lecturing me on applications of least resistance. Your early posts can act as little poster-boys for the classic bad demolition arguments.

Long time readers know we've been through this before.

Please provide more meaningful, useful comments or refrain from taking up space here. This is not a forum open to the public.

The 911 truth movement's claim is that the collapse which they denied occurred... since they postulate that the everything was exploded in sequence from top to bottom could not have taken 14 seconds since there was this pesky path of most resistance which would simply not let the material drop at .7 G or so. The top did not drop at free fall and there was resistance which made the collapse take 50% longer than free fall.

But 100,000 tons of debris is gonna be dropping pretty damn fast through the resistance of 4" lightweight concrete slabs on some flimsy bar truss joists.

How long does the truth movement claim such a collapse SHOULD take? Show me the math.

The path of most resistance, that is claimed on the home page of the AE911T website.

Again I think this is just a simple misreading.

Nobody is arguing that the thing went through the path of most resistance. But it did go through the path that WOULD HAVE BEEN most resistance had it been a natural collapse.

Most of the arguing I see here is about semantics rather than mechanics.

Long time readers know we've been through this before.

Yeah, you see that's not really impressive to me:
http://en.wikipedia.org/wiki/Groupthink

Maybe I'm just a muckraker though.

How long does the truth movement claim such a collapse SHOULD take? Show me the math.

It doesn't matter...

Or I should say, it doesn't matter outside of those who find the engineering puzzle an interesting thing in and of itself. But if that is the case you have to ask yourself why you are not studying the collapse rates of x-mas pudding instead.

Do you want mechanics? What force is present that displaces a 12+ story chunk of building 60+ m to the side so it falls through air? Gravity is directed downward.

The relevant principle is principle of least action.

Do you want mechanics? What force is present that displaces a 12+ story chunk of building 60+ m to the side so it falls through air? Gravity is directed downward.

The relevant principle is principle of least action.

Yes.

Least action is off the building.