Name five or six engineering professors who would be able to explain it.No engineer should have been puzzled by the runaway floor collapse.
Name five or six engineering professors who would be able to explain it.No engineer should have been puzzled by the runaway floor collapse.
Guy Nordenson comes to mind. I don't recall the names but... I attended a "AE911T" presentation at New Jersey Institute of Technology. The usual Gage dog and pony show. Didn't convince the students and 4 or 5 profs I spoke with thought it was bull pucky... including the head of the Civil Engineering department. I have two close friends who are profs / were profs at Universities and they would be able to explain it... also thought 911truth was rubbish.Name five or six engineering professors who would be able to explain it.
PM me. If you can put me in contact with a curently active engineering professor who is wiling to explain this in detail, step by step, and without any talk of controlled demolition, I am all ears.I have two close friends who are profs / were profs at Universities and they would be able to explain it... also thought 911truth was rubbish.
I would bet that all the prof at the department of civil engineering at my alma mater CMU can explain the collapse without missing a beat.
Anyone who has any understanding of structure and awareness of the pre collapse conditions finds the collapses were inevitable.
Go ask... and convince yourself,
And that is correct and adequate for most general enquiries. BUT misses the point here. SOME people want to know how the "descending debris" "blew everything away". Specifically:I dunno, y'all. As an informed layman, I tell people that each building got destroyed by a descending debris shield that blew away everything in its path. How much detail does the general population need to know? It's like, people generally accept that an object from space did away with the dinosaurs, and they don't go asking what was the composition and altitude of the ejecta or the exact environmental conditions that followed.
That is exactly the situation underpinning this debate which keeps going round in circles.It's still very close to how it happened, much closer than the CTs, and the mistakes are the result of an honest quest for knowledge.
That is always a desirable point in explanation. In fact SOME aspects of explanation need to distingush four sub-stages of mechanism.But if we distinguish sharply between initiation and progression, and asked,
That is near enough the "Limit Case" argument from Bazant & Zhou 2001-2. The accepted answer by those who are clear it is a "limit case" is yes. (There is a proviso I'll explain later.)"If for the sake argument the top block had moved freely straight down onto the bottom section "through the height of one floor" then would/could the collapse have progressed as a series of column failures, each localized to the story immediately below the collapse front?"
would the answer here be that yes, Bazant would be right in this (impossible-to-initiate) "limit case"?
I think "Yes!" But I'm not clear what you are intending.That would go directly to the truthers' "What if we lifted the top section the height of one story with a crane and dropped it?" scenario. It would debunk their intuitions about "the path of most resistance" etc.
Wanna bet? Just separate the members into (a) those who can process generic argument without needing the specifics and (b) those who cannot.The only interesting discussion was the cause(s) of the "initiation"... All steel AND concrete subject to out of spec heat was effected but some elements more than others and it's essentially impossible to know what was going on.... and where.
The engineering world does know why the progression of the collapse after initiated. NIST published this, and if 9/11 truth would read NIST, the collapse progression is explained. (hint, a floor in the WTC fails above 29,000,000 pounds, in general)...
The worry I have these days is that the progression of the WTC collapses is actually not known by engineering science. (It may be known by an engaged community of enthusiasts who have been developing the ROOSD model outside the confines of "academic" engineering research.) That is, I worry that engineers, as a profession, don't understand what happened to the structures of the of Twin Towers after the collapses initiated.
I hope I'm wrong about this. If I am, there will be a handful of engineering professors who can set me straight. Who are they?
Floor beams of large span - is part of ROOSD, large span = Open Office... Bazant beat MTbecause the structure is a framed tube with floor beams of large spans, the impacted floors may collapse ahead of the tube, thus depriving the tube wall of its lateral support against global buckling. (from https://archive.siam.org/news/news.php?issue=0034.08 "Why Did the World Trade Center Collapse?" Oct 2001)
That much is true. And it is true the several times Keith Beachy repeats the same in the remainder of the post.As seen in NIST facts, a floor in the WTC fails when over loaded past 29,000,000 pounds. This is the progression. Don't need an engineer to explain this. ROOSD is not needed, just the fact when the connections of each floor are added up, they can only hold so much. AT collapse initiation there was more mass falling than the first floor hit could hold, and the collapse could not stop. This is an engineering fact. Thus the progression of the collapse is Known, and can be seen by video.
Also similar to the Champlain Towers South collapse initiation (although the progression there was crush-up because the failure was at the bottom).But "progressive failure" also involved the progression of failures laterally through the frame as failed column loads were transferred to adjacent columns and this was a progressive process... similar to how a sink hole often grows in diameter.
"Least resistance" in structures is statics: broadly simplified, the part that's overstressed the most fails first. (which is also why cars have crumple zones now.) (Also, this is knowledge hard-won by playing bridge construction games.Path of least resistance is electricity, not buildings falling - using "path of least resistance" nonsense, debunks 9/11 truth on the spot.
If I was that professor, I'd ask you whether you have read and understood the NIST report before re-explaining all of that. I would also ask you to read "Why Buildings Fall Down" by Matthys Levy. (It's the sequel to "Why Buildings Stand Up".)PM me. If you can put me in contact with a curently active engineering professor who is wiling to explain this in detail, step by step, and without any talk of controlled demolition, I am all ears.
Academics consider it part of their job to answer questions from the public within their area of expertise. This "service" function is often mediated by journalism, but it can take the form of answering a mail from a private citizen. Sometimes academics even write popular books or make videos unasked to share what they know. They will often say both that they enjoy explaining things to laypeople and that it challenges them to think more clearly. So I'm not as pessimistic about this as you are. The important thing is to pick the right expert."Give an unpaid lecture on the WTC collapses to someone with no engineering knowledge" is not what I'd consider a polite request.
Those are the two main reasons I became involved in and remained in these discussions. It was a lot more rewarding back in 2007-2013. Both "sides" were learning and lots of persons wanting to understand more. Then serious interest in the engineering declined in the on-line "layperson" discussions. Academic discussion had stagnated about about 2009 or 2010. Hence much of the reason the Bazant <> NIST et al differences have not been resolved in the domain of academic/professional formal publishing.They will often say both that they enjoy explaining things to laypeople and that it challenges them to think more clearly.
What interests me now once my technical curiosity was "satisfied" (more of less) was how people responded to and reacted to the event... maybe mass psychology... hive minds and so on. It seems crazy to me that the truth movement still has legs and people can be pulled into the rabbit hole... intelligent people. I can only attribute this to a widespread distrust of authority, government and even science.... and that environment nourishes conspiracies. Religion of course is anti science and so many people have "faith" and will follow what amounts to irrationality without hesitation. You can see this in the Gage story as his anti vax beliefs got him expelled from AE911T which "pretends" to be science and engineering based. I think the origins of the truth movement was very much anti establishment anti media... But like anti vaxxers they use (junk) science to support and sell their anti authoritarian anti science beliefs.Those are the two main reasons I became involved in and remained in these discussions. It was a lot more rewarding back in 2007-2013. Both "sides" were learning and lots of persons wanting to understand more. Then serious interest in the engineering declined in the on-line "layperson" discussions. Academic discussion had stagnated about about 2009 or 2010. Hence much of the reason the Bazant <> NIST et al differences have not been resolved in the domain of academic/professional formal publishing.
I suggest "ranking" those issues in "order of importance".Perhaps... and this is just a guess.... one of the least discussed aspects of the collapses was the roll the engineering designs played. Could other engineering design solutions have not collapsed? This is of course theoretical. But it does seem there should be some objective way to assess "survivability" of a high rise. It hardly matters in the WTC disaster. The buildings were sound and the failures can be attributed to out of spec conditions. Can we expect more robust strategies to resist fires than were used at the WTC? Should a "collapse arrest" feature by included?
As you know incident, emergency and counter-disaster management was a strong "sideline" of my career. I've been astonished at how those FDNY commanders managed to continue functioning and making the right "calls" through that incident. e.g. despite ~20 years of truther mendacity "pulling" WTC7 was the correct choice. So much for "on the day" command of response. The later political response and consequences is a far more complex discussion.What interests me now once my technical curiosity was "satisfied" (more of less) was how people responded to and reacted to the event... maybe mass psychology... hive minds and so on.
I was referring to the post collapse "dialogue" and the rise of conspiracies...As you know incident, emergency and counter-disaster management was a strong "sideline" of my career. I've been astonished at how those FDNY commanders managed to continue functioning and making the right "calls" through that incident. e.g. despite ~20 years of truther mendacity "pulling" WTC7 was the correct choice. So much for "on the day" command of response. The later political response and consequences is a far more complex discussion.
Indeed. It is surprising (and, to some, a bit suspicious) that it doesn't yet exist.So what Thomas B is after is not something unknown.
This something Uwe Starossek explicitly takes up in his book, Progressive Collapse of Structures, as I recall. I don't remember what he concludes. Judging by his list of publications, he's quite the expert on progressive collapse.Could other engineering design solutions have not collapsed? This is of course theoretical. But it does seem there should be some objective way to assess "survivability" of a high rise. It hardly matters in the WTC disaster. The buildings were sound and the failures can be attributed to out of spec conditions. Can we expect more robust strategies to resist fires than were used at the WTC? Should a "collapse arrest" feature by included?
That's not a question we can answer. What we know is what type of fire the building was designed to be protected against.What's the biggest fire the buildings could have survived? (Or, more precisely, what's the worst combination of structural damage and fire progression that the buildings could have survived?)
Same thing, obviously the buildings were still up after half an hour of fire, but how short exactly is not a question we can answer with the data we have.Similarly, one could ask whether the buildings could have survived a shorter fire (i.e., one that was put out sooner).
Same thing, how much weight could exactly have been dropped on a floor? You have an expectation that the means exist to answer these question, when they don't.Finally, and I think either Starossek or Bazant (or both) mention this in passing, we could how high the planes would have had to hit for the buildings to survive.
The opposite is true: without an understanding of how to derive these answers from the construction drawings, the questions can't be answered. And if the knowledge needs to come first, it is much easier to acquire through experiments.So identifying the limit cases would be quite useful in helping us to understand how strong the buildings were and why they weren't built much stronger.
There was no silence. Building codes were changed as a consequence of 9/11.Again, this is something engineers would have done well to be talking openly about all these years. Their silence,
Article: The structural engineering profession studies events such as those of 9/11 to improve practice. Many of these studies, conducted by organizations such as the Structural Engineering Institute at the American Society of Civil Engineers (SEI/ASCE), the National Institute of Standards and Technology and the Federal Emergency Management Agency, have documented characteristics, such as redundancy and ductility, that enhance resistance to extreme assaults. Building on that information are researchers and practicing structural engineers striving to make our structures safe and economical for everyday use and also survivable when damaged.
I'm not sure what you're trying to accomplish by insulting me. But it seems to me that you should follow your gut here and, well, avert.In a retail context, that behaviour would get you labeled as a "Karen" customer.
(Seeing someone imply that answers should exist that shouldn't, and implying that information doesn't exist that does, produces a visceral aversion reaction for me.)
Hence my reference to "The later political response and consequences is a far more complex discussion." The focus of much of the debate has been on CT aspects. And - as this thread and its previous incarnations show - there has actually been very little discusion of the collapses in the professional literature. Most professionals understand that the collapses were "progressive failures" and have little need to debate the details. The details are neded in discusion with lay persons and especially when rebutting CT claims based on misunderstanding. Hence the reason the on-line debate is both divergent and in some aspects further advanced than formal academic discussion of "papers".I was referring to the post collapse "dialogue" and the rise of conspiracies...
I think the online guys such as you, femr2, Oystein etc... were more interested in the details and paid close attention to the visual record to inform their thinking.Hence my reference to "The later political response and consequences is a far more complex discussion." The focus of much of the debate has been on CT aspects. And - as this thread and its previous incarnations show - there has actually been very little discusion of the collapses in the professional literature. Most professionals understand that the collapses were "progressive failures" and have little need to debate the details. The details are neded in discusion with lay persons and especially when rebutting CT claims based on misunderstanding. Hence the reason the on-line debate is both divergent and in some aspects further advanced than formal academic discussion of "papers".
EXACTLY. Put simply most early analysts adopted macro level simplifications and ignored the actual mechanisms of collapse.I think the online guys such as you, femr2, Oystein etc... were more interested in the details and paid close attention to the visual record to inform their thinking.
Apologies, I don't intend to insult you.I'm not sure what you're trying to accomplish by insulting me. But it seems to me that you should follow your gut here and, well, avert.
YOU NAILED IT! Hall of fame!EXACTLY. Put simply most early analysts adopted macro level simplifications and ignored the actual mechanisms of collapse.
And thereby made what should have later been recognised as two fundamental errors. This thread is actually floundering over those same two errors.
Those early analyses followed two false trails. The first was focussing on the macro motions. 'Why did progression proceed at about 2/3rds "G"?' The second was chasing "One dimensional approximations" Nobody seemed to attempt to anlyse "what actually happend" i.e. tried to explain the actual collapse mechanism.
The NIST Report explicilty did NOT explain the progression stage tho - if you read NIST carefully - the principles were understood but not explicitly stated. Bazant & Zhou's limit case was a 1D approximation and thew "Tube in Tube design is as far as possible from being suited to 1D approx. OK for the B&Z 2001-2 "Limit Case" even tho many got it wrong. Totally wrong when replayed in B&V 2007 as "CD/CU".
And that is the central error I identified in that Wikipedia article - Bazant & Verdures "CD/CU" is a 1D approximation. The same error that the online debate has mostly broken out of is still reflected in the professional literature which has stagnated, And the ambiguity faithfully presented in the Wikipedia argument.
All three were subjected to fires that were bigger than specified in the design parameters. That aspect is ignored or lied about by truthers claiming "office fires". A mendacious play on words. None of them were the "office fires" the buildings were designed to withstand.All 3 collapsed totally... and all were subject to fire/heat not effectively mitigated.
Correct. The fire sprinklers had a lower floors zone supplied by mains pressure then higher level zone or zones provided with buffer storage tanks and replenished by pumping. I cannot remember more details. Of course failure of water mains meant no sprinklers to the lower zone and only minutes supply for upper zones. And the killer >> deliberate choice to not invoke the regime of "active firefighting" which would include "feet on the ground" firefighters but also booster pump replenishment of water for both sprinklers and firemen's hoses. >> and no mains electricity power available therefore replenishment would involve ad-hoc electricity supply generators >> it gets worse doesn't it?All 3 collapsed totally... and all were subject to fire/heat not effectively mitigated.
7WTC was not flooded with jet fuel. There was fire fighting and sprinklers... but as a result of falling debris the water main which supplied 7WTC was destroyed and could not replenish the sprinkler system. There was also loss of power... which may have rendered the lift pumps for the sprinkler system inoperable. (don't recall what kind of sprinkler system the building had).
Take care that you don't get lost in circularity chasing your tail. Remember the design includes - is premised on - the "three hour fire rating" So the "How long...?" questions are subsumed in the assumptions about "active fire fighting commenced within three hours.." (And not forgetting the PRIMARY objective of fire rating - "All occupants escaped")But I am curious about the amount of fuel to generate the heat to do its thing to the steel in the col 79 vicinity. How long would typical office fires burn... before they consume available fuel?
There was fuel stored in the building but not on the floor we are told where col 79 "failed" and the collapse was "initiated". This is confusing/concerning. But I suppose it unlikely that a fire would be allowed to burn that long under "normal" circumstances.
I don't know how long and hot the fuel load on that floor at that location was. I know about hr ratings and the build supposedly had fires bring 6 or 7 hrs .... I don't recall... but longer than 3 hrs. So of the contents was typical and there was no sprinklers... and no active fire fighting... another building could see the same fate... at least lose a column and surrounding floor. Successful load transfer would be dependent on the steel design... beams, girders and floor plates.Take care that you don't get lost in circularity chasing your tail. Remember the design includes - is premised on - the "three hour fire rating" So the "How long...?" questions are subsumed in the assumptions about "active fire fighting commenced within three hours.." (And not forgetting the PRIMARY objective of firerating - "All occupants escaped")
Don't miss the key point. No active fire fighting and it still lasted nearly twice the fire rating. To my thinking that subsumes all the concerns about how much fuel. Again - come at it from yet another direction - if you have a building designed for active firefighting starting within three hours (MAXIMUM - probably far less) AND you deliberately leave it without either active fire fighting OR working sprinklers >> you deserve what you get. Probable collapse.I don't know how long and hot the fuel load on that floor at that location was. I know about hr ratings and the build supposedly had fires bring 6 or 7 hrs .... I don't recall... but longer than 3 hrs. So of the contents was typical and there was no sprinklers... and no active fire fighting... another building could see the same fate... at least lose a column and surrounding floor. Successful load transfer would be dependent on the steel design... beams, girders and floor plates.
I don't know what the 3hr rating is actually for... time to do active fire fighting? Time to evacuate? I don't think it means time to total failure...Don't miss the key point. No active fire fighting and it still lasted nearly twice the fire rating. To my thinking that subsumes all the concerns about how much fuel. Again - come at it from yet another direction - if you have a building designed for active firefighting starting within three hours (MAXIMUM - probably far less) AND you deliberately leave it without either active fire fighting OR working sprinklers >> you deserve what you get. Probable collapse.
Yet another alternate "take". Of course another building would risk the same fate. It is NOT guaranteed but...
And all the details as to how it fails are not relevant to the primary question "Would it fail?"
Both those two - and the order of importance is reversed so: Time to evacuate and time to START active fire fighting.I don't know what the 3hr rating is actually for... time to do active fire fighting? Time to evacuate? I don't think it means time to total failure...
LOL.Apologies, I don't intend to insult you.
I was trying to characterize your line of discussion, not trying to say anything about you personally.
Yeah, that's not how I wanted that to come across, sorry.You almost literally said, "Your type ('Karens') make me puke ('produces a visceral reaction')."