???? Pls copy/paste what I say. It seems you are in the small text introduction that I added the other day to the article to make readers curious what follows.
Pls read the complete article! It starts below the small text!
WTC 1 & 2. What happened after collapse initiation?
- Thread starter tanabear
- Start date
???? Pls copy/paste what I say. It seems you are in the small text introduction that I added the other day to the article to make readers curious what follows.
Pls read the complete article! It starts below the small text!
Non-related field?
All experts wrong?
Sorry, what are you talking about?
And pls - don't call me a random guy. Random means apparently 'without aim or purpose' and I evidently have a clear aim and a distinct purpose. Don't you agree. Worried about that?
Topic is however WTC 1 & 2. What happened after collapse initiation?
Topic is not my person! Very interesting, of course, but OT. Random makes it even more confusing.
I have evidently some interesting info about topic (not random); that local failures take place to both parts, that the failures would be arrested, that friction must be considered, that basic assumptions by Bazant are wrong, that NIST's analysis is incomplete, etc, etc. Let's discuss those.
My person is of little interest except to my girl friend. What do you think about my observations? Topic! My girl friend thinks I have good ideas!
I can evidently reply to stupid questions about the strength of bolts and tilted squares squeezed through parallell lines ... but why not discuss topic.
BTW - what is 'kook'. Can't find it in my English-English, English-Japanese, English-German, English-French, English-Arabic dictionaries. English is not my first or second or third language or fourth language. And I have difficulties to understand American slur.
Does he mean a cook? Advice - do not cook a soup in a basket.
Or a book? Ever read one?
Or a look?
Or he cannot spell?
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Worried about that? Or you could not do it yourself? It is simple! Anybody can do my experiment.
Bazant is a serious researcher. You are an incompetent fraud. If you drop the top third of a building from a height of two miles onto the bottom two-thirds, you OBVIOUSLY destroy the whole structure.
Your errors have been pointed out to you repeatedly by people who know much more than you do. You are ineducable.
I'm worried about how people who do your experiment should measure the temperature of the legs, to determine when they've reached 500 degrees C. (or determine what temperature they actually do reach.) If your experiment is simple and you've done it yourself, then you should have no trouble describing the instruments you used. Why won't you reveal this information?
Respectfully,
Myriad
Newtons Bit
Penultimate Amazing
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You keep saying it's not possible, and I keep posting a picture that shows it is.
And guess what, this was actually recorded.
And what caused this? The collapse initiation was one wall being pulled inwards. This instability was due to a small 4 kip pull-in force combining with a reduction in the modulus of elasticity due to fire. Thus one side fell before the other, INSIDE the building.
Mashuna
Ovis ex Machina
What's not clear? You say you've modelled collisions in ships, the WTC1 and 2 are not ships. Thus, non-related field.
You're claiming you're right, and people who are experts in building demolitions are wrong.
You're someone I've never met, and you have a webpage. Random, in this sense, means I have no way to distinguish you from anyone else claiming special knowledge with a webpage.
For me, the topic is this. Why should I, as a non-expert, pay any attention to your website. There are many websites claiming all sorts of things. Yours, to me, looks no different to any others. You claim it is not important to submit your claims to a journal, I'm trying to explain why I think it is.
I'm not American, but here's your definition (it's not necessarily a slur):
Mashuna
Ovis ex Machina
I replied to the copy/paste that you made yourself. It may just be an issue around how you're using the term 'follow-up'. I don't think your paragraph reads how you want it to. It's not one of the big problems.
Grizzly Bear
このマスクに&#
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I'll be more than happy to point out what I question in your paper. You can take it how you will. I'll try to group sections dealing with the same topic to avoid answering duplicate questions.
What characteristics of this analogy match with the world trade center collapse:? My observations are the following:
- What similarities do the construction of ships share with the construction of the twin towers?
- What similarities are typical in collisions between two ships and two sections of the same building? Do ships typically have gravity as a driving force in the collision like the buildings had?
It comes off to me as an apples vs oranges comparison. I'm an architecture student meaning that I am somewhat of a layman as far as engineering is concerned. If you can clear this up I'd appreciate it.
- In order for there to be momentum and/or velocity there must necessarily be acceleration. So in effect this assertion is wrong. Regardless of the failure mode whether it's what you'd like to have us believe, or otherwise the net acceleration begins at zero and increases the moment the mass begins to fall. This may very well confuse readers, it certainly comes across as odd to me.
- This may very well be true for ship collisions but I still fail to see how it mutually compares to man made structures that must constantly resist a gravitational force. A ship is built much differently than a building as you must be keenly aware of. In the end this boils down to the same question I began with; what is mutually common structurally speaking between a ship and a skyscraper that dictates the behavior under failure conditions?
- I appreciate that your passage here addresses one of my complaints, but not completely. Again, this boils down to my very first question, and how they are structurally alike. In other words what validates your analogy here?
- These failures sound a lot more typical of post and beam construction methods that are common in traditional steel frame design (seen here). Source Article
- The world trade centers were built much different than this however. If some of the core columns failed, the loads were transferred via the hat truss at the upper-most floors to the perimeter columns. If either system failed completely, then there's little to nothing to arrest further collapse. The structure was built roughly the same all the way up with variations in columns thickness varying as required for loads.
You've obviously listed a number of other criteria but for me to address them will require more time. For now I will respond to what I can readily respond to.
- [For (7)] --- Has it occurred to you that the columns were subjected to a multitude of shear forces? Both gravitational and lateral from the building itself?
- Why did the perimeter columns separate into thousands of pieces 10-12 meters long? It is clear that when you wrote this paper you did not study the towers as well as you claim. The columns were not continuous pieces along the entire height of the towers. They were built in sections approximately 12 meters (3 stories) tall/long. They all separated because of the explanation provided below for (9).
- [For (9)] --- First of all this is false. Flat-out false. NCSTAR 1-3C provides information for connection failures in the structural components. The claim that they have not explained this is therefore wrong. They also explained this same thing for the columns that were directly hit in the plane impacts.
I have not read Bazant's paper in full detail so I will read this as if taking the point at face value. If in fact they model it as if the upper section is 'indestructible' then I have perfect criticisms in their justification for doing so. However, I can also accept that the upper block does not need to be totally intact to progress the collapse; only sufficient mass to overpower individual structural components in a domino effect. If anything that appears to be the gist of their model.
However, you must keep in mind as well that it's a highly simplified model of a complicated collapse event, and should be interpreted accordingly. Those who have truly read Bazant's paper have a better idea of his actual content, my criticism of the model itself in terms of visual representation may change upon reading it comprehensively however, looking at the model without prior reading I have my views of it.
I expect this behavior with noodle, not with interconnected column sections. The moment this deformation impacts connection points, can you honestly say that deformation will not result in some kind of connection failure?
Remember that unlike in your proposed experiment we're not dealing with a structure with only 4 columns, We're dealing with a structure built with 47 core columns and over 200 perimeter columns. No single columns can support the entire weight of the building, Columns working as a system can. The scale of weight and load bearing is worlds apart. THis is a flawed logic on your part.
The next part I got to was this: Collapse Model
I've already addressed this. You're treating the structure like a traditional steel frame building. This model holds little significance as it does not accurately depict the way in which the structure was built: Core columns in the interior, and perimeter columns on the exterior. THe core housed mechanical services (elevators, wiring, plumbing, etc).
Next was your section on other potential collapse scenarios: Postulated model
This one equally fails to accurately represent damage to the core structure as part of collapse analysis. The core, is designed to take half the loads, your model suggests that the core structure is still capable of carrying the floor loads without the lateral bracing offered by the perimeter, but also assuming that it would be capable of supporting all floor loads from the upper section ins an already weakened state. This is not the windsor tower Heiwa.
For the two scenarios you posted, I don't know if those are the types of examples you expected to convey through these, but as a reader that's how it comes across to me.
- This statement in figure 8 of your paper simply baffles me. Look at any video and you will see the dust cloud in the wake of the main collapse being pulled in by air currents following the mass. Is this your idea of a straw man?
It's absurd that you've made the same claim as a number of other members on this forum. That was a very simple observation and you misrepresented it.
- No Heiwa, the air being forced out by the pancaking structure causes these air jets. That is, unless you plan on arguing that the explosives were not only to weak to cause the exterior structure to 'explode outward', and so strong that they were capable of it. Paradoxes do not work here...
X
Slide Rulez 4 Life
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No. There are equal forces. This is hardly the same as claiming there is equilibrium.
More or less, and as near as can be determined from analyses which require assumptions.
Correct. And this is where the roles of gravity and momentum becomes very important. Remember, as more of the lower section is destroyed, more mass is added to the falling section.
For the falling sectoin to stop, the building has to provide enough force to couter not only the initial moving mass, but the mass gained as is moves downwards.
If the building is incapable of providing a sufficient amount of retarding force, the falling section will accelerate, thus requiring even more force to bring it to a stop.
But is it enough? You seem to be asserting that it is. Please preovide calculations backing this argument up.
Uhh... Sure.
This is why the floors and everything in between wound up compacted together.
Bazant made his assumptions, made his justifications for them, and backed them up with calculations. I'm not going to say his paper is perfect. Nothing with assumptions can be. Unfortunately, in engineering, assumptions are necessary or solutons will never be found. WHich is why engineers typically try to err on the side of caution when making calculations.
If I am recalling correctly (I could have different papers mixed up), Bazant made assumptions favouring the halting of the collapse.
Excellent! An assertion. I assume, since you are an engineer and well-experienced in such things that you have the calculations to back up this claim. Please provide them or I shall defer to the explanations of those who have provided such calculations.
Seeing as the towers were destroyed, I do not see how such conclusions are "evident". Please provide your justifications. Calculations would be nice.
So far, so good.
Not quite. The force F, being applied to the brick, does not have an equal and opposite reaction on the surface of the table. If it did, the forces would be in balance and the brick would not move.
Rather, is is the force of friction (which I shall call H) that has an equal and opposite reaction on the table.
The force of friction between the brick and the table is, of course, the perpendicular force to the contact plane (weight, in this case, which is mass x gravity) multiplied by the coefficient of friciotn between the surfaces.
H can at most be F, and if the brick is moving must be less than F.
Ignoring the confusing of force applied to the brick and friction, this seems correct.
Correct.
Correct.
Energy is always being wasted. Sometimes I feel just bothering to post in the CT subforum is a waste of energy.
My example was merely attemtping to illuminate what I thought was a misunderstanding between you and Mackey, the there would also have to be aforce of friction acting downwards against the lower structure in your scenario, equal to the one retarding the motion of the upper section.
Grizzly Bear has pointed out that I may have misunderstood the misunderstanding.
NIST had one goal, and that goal was not to perform an in-depth analysis of the collapse.
NIST was only concerned with what happened up to collapse initiation, and then showed that once initiated, the building was of insufficient strength to arrest the collapse.
This has been pointed out to you before, so please stop harping on NIST for not doing something that wasn't part of their job.
There are other competant and knowledgeable individuals who have taken more detailed looks at collapse progression, and their findings have agreed with NIST at least insofar as saying that once started, the process was unstoppable.
Except, it would seem, the individual who designed it, uses it as a principle argument, and figures children should do it. And who has so far been unable to provde any calculations validating the model as an accurate scale representation of WTC 1 or 2.
After all, it only costs a few hundred dollars, and involves fire and dangerous substances. Perfect for children!
Do you perhaps mean adolescents (14ish-18ish), Hiewa? "Kids", in the Western world, is generally assumed to mean young children. Under the age of 14 or so.
Do you really think 9-year-olds should be attempting your experiment?
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Am I worried that you appear to have invented experimental results rather than measure them? Yes.
It is for you to dispel these concerns by supplying documentary evidence that you have actually conducted the experiment. Or simply concede you have never done it.
Quite a good description of the situation. But NIST didn't show that, after initiation (the topic), that collapse would ensue. NIST just said that there was not enough strain energy in the structure (no calculations) to absorb the potential energy released (no calculations) so that collapse would ensue. NIST conveniently forgot further local failures, further displacements of parts, friction between these parts or that complete walls would have displaced outside the structure below that would have arrested the destruction before any loads were transmitted to intact structure below. Sloppy work, simply said.
And when this is politely pointed out to NIST, they just reply in an updated FAQs that the top intact floor could carry a lot of floors but, when sufficient floors were loaded, the top floor would fail. That is not an explanation for global collapse.
Bazant's theory has been totally debunked. Like NIST Bazant ignores further local failures, further displacements of parts, friction between these parts or that complete walls would have displaced outside the structure below that would have arrested the destruction before any loads were transmitted to intact structure below. Bazant assumes perfect alignment of an upper block that remains 100% intact during a 'crush-down' after initiation, when a child understands that the upper block cannot remain intact and that perfect alignment is impossible. This crush-down theory is simply stupid.
And that's where we stand today.
A ship is a steel structure and WTC1 is a steel structure = related fields.
Re topic, pls start a new thread about your personal worries.
A. They are steel structures where the primary loads are carried by primary members.
B. Momentum and energy are transmitted. Upper blocks are driven by gravity, ships are driven by thrust of a propeller.
C. Correct - but the acceleration took place prior to the collision. We are looking at what happens afterwards. And we start with the instance of contact where only mass and velocity count.
D. After initiation the columns are assumed disconnected and misaligned, i.e. no upper columns put any load on any lower columns. Any load from above must pass through the floors that evidently fails. After arrest evidently all the load from above pass through the locally failed parts (floors) and contact points of entangled floors (the arrest zone) and will be transmitted to the intact columns below as before initiation. Evidently there will be lateral forces applied on the columns in the arrest zone, but these columns are not subject to compression any more. I assume the lateral forces will be resisted by the spandrels. A complete structural damage analysis will confirm this.
E. I have summarized Bazant's paper in my article + provided a link to Bazant's paper. Read it.
F. My 4 column model test is just to show that four columns under compression do not fail heated to 500°C.
G. As shown in my article there is no pancaking structure. Only partially failed floors in the arrest zone; the floors are damaged by the columns, but still held at one edge like a hinge. Air jets are not possible. Actually, the local failures I expect would not produce any rubble at all.
Thanks for your interest in my articles.
Re your other comments I think they are correctly described in the article without further comments.
If you read my article carefully you should see that, when the floors of the lower section in the arrest zone fail and then break the floors from above - also locally damaged - by friction, no extra mass is added to anything, particularly not to the upper block that is being destroyed. Only energy released is wasted due to friction.
Thus - the total mass remains constant (except the mass of two upper walls that should drop off outside the structure below).
The energy of the moving mass of the upper block, or what remains of it, is wasted as friction in the arrest zone (apart from the energy that is absorbed to produce the local failures). No mass is added to anything.
It is quite easy to make that mistake when you are not familiar with structure damage analysis.
After arrest, the gravity loads/forces of the failed upper parts are evidently transmitted to intact columns below as explained to Grizzly Bear above.
Thanks for your interest in my article.
And evidently two other sides of the upper block should fall outside at such an initiation - quite clear from the picture actually (I use it too in my article)! What happens afterwards is described in my article.
I am happy that you assist in debunking Bazant that assumes a vertical drop without misalignment at initiation. Welcome to the Truth and Justice group of people.
What's wrong with a thermometer? Mentioned in the model test description. Pls read!
A thermometer ?
Quite a lot, I would have thought. I'm no research scientist but (off the top of my head) I would be looking at measuring the fireward surface, outwards-facing surface and internal temperature at maybe 4 points on each of the 4 legs.
I make that 48 thermocouples wired up. Perhaps 24 would do.
Please add yet another safety note to your "children". Do not approach this contraption with "a thermometer" as you are likely to experience serious burns and quite possibly be killed.
Heiwa - have you conducted this experiment yourself? Yes or no.
JihadJane
not a camel
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gumboot - ->
*****Of course simple physics will tell you that the cores alone - especially after the battering of the collapse - simply could not remain standing for any length of time. Tall thin structures are far too unsteady - which is why radio towers are stabilised with cables. *******
Very funny!
*****Of course simple physics will tell you that the cores alone - especially after the battering of the collapse - simply could not remain standing for any length of time. Tall thin structures are far too unsteady - which is why radio towers are stabilised with cables. *******
Very funny!