John Jones
Penultimate Amazing
Total Building Collapse from a Single Column Failure
- Thread starter JSanderO
- Start date
-
- Tags
- wtc collapse wtc7
Hearing is not understanding.
jaydeehess
Penultimate Amazing
Failure of col 79 causes debris rain on lower floors includin #5 and in the vicinity of TT1(and others).
In addition , as col 79 drew down floors all the way to the rooftop it would be pulling in floor pans around it, causing stress on beams and girders attached to other columns. So you have lateral pull on columns plus heavy debris buffeting from falling debris. Then, once the EPH does tilt, you have whatever heavy machinery was in it also coming down.
Nice try... but no cigar.
jaydeehess
Penultimate Amazing
You don't think that a buckled col 79 would cause heavy debris rain on the 47 floors along its length?
You don't think that , specifically in WTC7, that this would affect lateral bracing of nearby columns?
You don't think that machinery(hvac or elevator motors) falling 42 storeys could destroy , say, TT1?
I find that if a girder on flr 13 walked off its seat... that the local floor area it supported would not come crashing down on to floor 12 with such force as to destroy the floor area or knock the same girder off its seat... or certainly cascade down to the load transfer structures one after the other.
No I don't.
If it did, which it likely wouldn't... it would leave a column un braced on 1 of 4 sides and not subject to Euler buckling... said columns would be no different than the bracing that a perimeter column has - 3 sides.
And I don't think removing the girder by any means would buckle column 79 at flr 13 either. Do you?
Why?
Last edited:
Mark F
Graduate Poster
- Joined
- Aug 4, 2012
- Messages
- 1,746
If there was enough heat to cause the girder on 13 to walk off does it stand to reason those same fires may have had an adverse effect on adjacent floors on that same column, making them more susceptible to catastrophic failure if one floor collapsed?
Mark,
I simply find the scenario implausible and a single girder walk off.. would not cause the column to fail from buckling. I further don't see why multiple floors around column 79 would all experience similar heating and girder walk offs...
Now how would that work... all at the same time?
How many floors of missing girders turns into a buckling situation?
I am not saying this is impossible. I am saying it seems both implausible and not explained.
Explain please.
Now Ozzie is going to repeat his column 79 had to fail for the EPH to collapse bit...
Last edited:
ozeco41
Philosopher
No - I'm not.
If this thread ever gets around to considering reasoned arguments starting from known facts - then I may be interested.
But chasing strawpersons and speculations whilst ignoring known facts simply ain't my scene.
EDIT:
PS From whence cometh this idea that girder walk-off all by its little lonesome caused Col79 to fail>>>>all the rest follows??
Last edited:
No - I'm not.
If this thread ever gets around to considering reasoned arguments starting from known facts - then I may be interested.
But chasing strawpersons and speculations whilst ignoring known facts simply ain't my scene.
EDIT:
PS From whence cometh this idea that girder walk-off all by its little lonesome caused Col79 to fail>>>>all the rest follows??
I quite agree with the thrust of this comment.
First... color me dumb but I have been laboring under the presumption that NIST explanation began with heat causing steel of the beams to expand and push the girder off the seat and that led to the column failure.. the part I don't understand or know if they detailed.
I've requested someone explain the process which led to the failure of column 79 and then to the global collapse. Actually I am not that concerned whether or not the girder walks.
As far as failure from Euler buckling, my understanding (limited) is that it is related to slenderness ratio and therefore the column needs to be COMPLETELY unbraced... ie having it braced by three beams such as an exterior column is not subject to Euler buckling.
So why does one girder walk off... or a series of the one floor above the other lead to Euler buckling?
Perhaps if someone could simply detail the process I could have the fog lifted. I won't say it's impossible. But I will say it's not been explained (to me).
Not related.. I don't think col 79 buckled. I think, as you may know that it was pushed over by the failure of TT #1 which had a beam framed over to column 79. and once it was pushed over all the column 79's above fell straight down. But that's another story and one that I CAN understand.
Last edited:
jaydeehess
Penultimate Amazing
I am not disputing that your TT1 led collapse is compelling.
It lacks one important thing, a proximate cause for it to happen. While I know you assume a diesel fuel fire, and at the time of the NIST interim WTC 7 report I argued for possibility of it being correct. However just the fact of missing fuel is not enough to convince me.
It lacks one important thing, a proximate cause for it to happen. While I know you assume a diesel fuel fire, and at the time of the NIST interim WTC 7 report I argued for possibility of it being correct. However just the fact of missing fuel is not enough to convince me.
ozeco41
Philosopher
OK
So let's see if we can agree what we are discussing.
We have five scenarios before us in this thread and we keep switching, mixing or conflating them. They are;
1) Mine which says - ignoring NIST and working from zero base and known facts:
(a) We know as fact EPH fell>>>Col 79 (and all associated structural elements supporting EPH) MUST have failed.
(b) I have said and asked for rebuttal of "there are only two possible ways Col 79 could fail - viz (i) imposed gross overload (humorously stated as 'EPH triples its weight by magic') OR (ii) Euler buckling". Since "(i)" is not possible THEREFORE Euler buckling.
(c) That requires removal of horizontal bracing. THEREFORE something removed the horizontal bracing.
(I pause there - I cannot answer the obvious next question (at this stage) - then I conclude with
(x) Girder walk-off and Sanders TT failure are both plausible as contributing factors BUT NOT as single factor "causers" or "leading to's"
We will never be sure of the details.(z) Therefore "So what?" - Who needs the details and why?
2 NIST's Explanation which was based on final FEA analyses of four alternate scenarios viz 3 different mixes of debris impact damage and fire-induced damage plus one involving the removal of a section of Col79 as the only damage input.
All four led to global collapse but with mechanisms differing in details.
3) Sanders partially defined hypothesis which seems to be based on Transfer Truss failure as the sole initiating factor - associated with rejection of the girder walk-off factor. IMO neither is a plausible "single factor cause" and both are plausible contributory factors.
4) Several other speculations about possible contributing bits of mechanism BUT non of them framed as a complete and coherent hypothesis.
5) Sanders questions from the OP which I have suggested are not sufficiently well defined to be meaningful base for discussion. This is the legitimate OP for this thread.
So we should decide which topic we are going to discuss.
I suggest at this stage there are only two. Viz:
#5) The OP Sanders original questions under the heading: "Total Building Collapse from a Single Column Failure"
This is the legitimate OP topic. However:
#1) MY reasoning from near zero base - because it is a legitimate way of "getting into" Sander's OP.
And we don't need to discuss:
#2 NIST's Explanation may look tempting .. but the only thing needed with NIST is that we stop strawman caricaturing NIST and recognise what NIST really said THEN fit the real NIST explanation genuinely into whatever we are discussing.
MEANWHILE
NIST NCSTAR 1A - page 38 for the global FEA material.
Do you mean "What actually happened?" which has been my main focus OR "What does NIST say?" Those are two different issues and you need to be sure which.
Neither am I - my main concern for months has been with the truther case AND the debunker rebuttals BOTH making the same errors of context and assumption setting. A lot of to-and-fro argument with both sides based on false foundations.
A ..completely unbraced over a critical length which is load dependent.
B More or less true - we would need to be very specific before I would be certain.
It doesn't and it doesn't always respectively. Whether it is your own or someone else's you are chasing a strawman.
which process? What really happened OR NIST's explanation?
You said it. I'll take your word for it- for now---"Not related"
Last edited:
If we confine the discussion to failure modes of column which progresses as you say we have basically two:
increase loads
decrease capacity
Loads were not increased
How can capacity decrease?
Heating lowers capacity
mechanical damage such as horizontal impact deforming column
removal of bracing increasing unbraced length lowering capacity. NB when a steel column exceeds a SR ratio of 150 it has left the stable region and become too slender. This applies to the each axis and the column will buckle from Euler forces with either axis exceeds 150.
Columns which lose a single brace may not have the SR changed if the remaining braces provide the restraint effectively maintaining the SR ratio. This is the case for example for perimeter columns and corner columns.
If one looks at the corner of the core of the twin towers... Col 501 for example was the most massive and presumable carried the most axial loads. It was framed such that it had a beam to its long axis web (short 22" side) The other axis had no bracing to column 502 but it did have a beam stub framed to a girder in the short axis which I suppose would be the brace. See the attached diagram. None of the column ends in the etc were restrained. All braces were some where between the ends at something like 3', 15' and 27' from the bottom of the column.
It seems to me.. that loss of a brace does not immediately lead to buckling, though it may lead to loss of capacity. I don't know. NB in the collapse of the twins columns 501 and 601 stood after the core strip down connected by the brace between them only. As a double column they were stable in the long axis but the SR ratio in the short axis far exceeded 150 and they toppled in the direction.
Euler Buckling in multi part (stacked columns) results in failure at the connection... the weakest point. The column to column connection does not require restraint to transfer axial loads. However Euler forces and buckling induce lateral forces in x and y axis and the splice connections are much weaker than the solid section and hence the unbraced multi part column buckles from Euler forces by having it's connections break apart. no web or flange crippling, for example. And this is what we see in the spire columns which failed from Euler buckling.
But
Did would happen Euler bucking if there was some sort of strip down of 5 floors on one side of a column especially with the dimensions of the 7wtc column 79 for example. I think not. I could be wrong.
A column may have twisted rather than buckled, broke it's connection to the one above and the whole line came down. Maybe.
I don't think col 79 experienced Euler buckling. Do you? It seems it would have to lose its bracing over something in the order of 20 stories (a guess as I don't know the size of column 79 at floor 13)... I did the calcs for Euler buckling see attached
Attachments
Last edited:
If one can rule out an Euler buckling scenario then the failure of a column line such as 79 has to be:
loss of support
rotation or translation out of alignment with the column line
mystery column destruction in the column line
I think too many people are attributing column failures to Euler buckling. I believe they are asserting the wrong mechanism. Euler buckling explains the spire collapse for sure.
However the failure more for most other columns in the world trade center was
fracture/parting/destruction of their end connection - column to column
There WERE some cases of buckling perhaps from heat weakening leading to loss of capacity
There WERE a few case of buckling from excessive axial loading ("new loads" redistributed in the last moments of top drop)
There WERE columns which were pushed off axial alignment (connections failed)
There were columns which lost support when columns below failed... column with no coupling to foundation can't support boo.
There may have been failures from multiple stresses and factors
My Assertion: There were very few to no failures from Euler buckling which drove the collapses.
loss of support
rotation or translation out of alignment with the column line
mystery column destruction in the column line
I think too many people are attributing column failures to Euler buckling. I believe they are asserting the wrong mechanism. Euler buckling explains the spire collapse for sure.
However the failure more for most other columns in the world trade center was
fracture/parting/destruction of their end connection - column to column
There WERE some cases of buckling perhaps from heat weakening leading to loss of capacity
There WERE a few case of buckling from excessive axial loading ("new loads" redistributed in the last moments of top drop)
There WERE columns which were pushed off axial alignment (connections failed)
There were columns which lost support when columns below failed... column with no coupling to foundation can't support boo.
There may have been failures from multiple stresses and factors
My Assertion: There were very few to no failures from Euler buckling which drove the collapses.
Last edited:
I completely agree that there is no real evidence of what caused the transfer structures to collapse. So while it explains to movements and matches the observations of the building the cause of the collapse can only be assumed.
NB that the heat claims of NIST at column 79 floor 13 are pretty much assumptions based on photos from outside the tower.
Have we seen any analysis of the steel of column 79 or the members framed into it? a resounding NO?
NIST's column 79 causes are simply made up inputs with a tad of evidence because we can see smoke from the region.
But
There are no cameras shooting low down all day long and none inside the building at any level aside from some early shots of rescue personal going into the lobby post the collapse of 1wtc.
There are anecdotal accounts of FDNY saying they say no fire. Cool... how extensive was their survey to produce that report? I don't think they lied. It's much like the report from 2wtc that there were isolated pockets of fire. There were! But that FDNY firefighter could not have done a very extensive survey for us to conclude that there were ONLY isolated pockets of fire.
Ergo... you have to be very careful in assuming that when there were no reports means X, Y or Z was not or did not take place. It only means that the observer did not observe X, Y or Z where and when he looked.
We have very little evidence to build a real world model on. Same applies to column 79 which is why it is so silly to think of it as a real world explanation. IT IS NOT. It is a made up (wrong) model. PERIOD.
NB that the heat claims of NIST at column 79 floor 13 are pretty much assumptions based on photos from outside the tower.
Have we seen any analysis of the steel of column 79 or the members framed into it? a resounding NO?
NIST's column 79 causes are simply made up inputs with a tad of evidence because we can see smoke from the region.
But
There are no cameras shooting low down all day long and none inside the building at any level aside from some early shots of rescue personal going into the lobby post the collapse of 1wtc.
There are anecdotal accounts of FDNY saying they say no fire. Cool... how extensive was their survey to produce that report? I don't think they lied. It's much like the report from 2wtc that there were isolated pockets of fire. There were! But that FDNY firefighter could not have done a very extensive survey for us to conclude that there were ONLY isolated pockets of fire.
Ergo... you have to be very careful in assuming that when there were no reports means X, Y or Z was not or did not take place. It only means that the observer did not observe X, Y or Z where and when he looked.
We have very little evidence to build a real world model on. Same applies to column 79 which is why it is so silly to think of it as a real world explanation. IT IS NOT. It is a made up (wrong) model. PERIOD.
RedIbis
Philosopher
- Joined
- Jul 22, 2007
- Messages
- 6,899
Not only is there very little evidence, there's no physical evidence. No Column 79, not trusses, no critical components. We call what NIST has provided a theory, but it's really a hypothesis.
The failing of both the truth movement and NIST is to explain a plausible SEQUENCE or PROGRESSION of what NIST call global collapse and the truth guys call it total destruction.
NIST fails in their attempt to come up with initiation scenarios and does not bother to carry them into the global collapse mode. And their JERF supporters can't or will not do it either... witness the responses to the thread Can a Single Column failure lead to Total Collapse... none of substance.
Problem
When something falls down... it loses the support which hold it together and keeps it standing. Or something takes that away or crushes it (a distinct change from the static state).
The over arching reason we are told is that heat renders the structure or nodes that hold it together below the performance profile to be self supporting.
We are told that structure have reserve strength... they do... which means that the normal operating stress is below the design stress. This is referred to as a factor of safety. For most this is only a concept which applies to the columns. This would be wrong.
Global/total collapses are not single causes... like a bomb blowing the thing up... but a series of failures of the components and nodes... thousands and tens of thousands of them... each one feed forward into a newly and less robust system.
The fog has been created by the failure of NIST and the anti NISTIans to articulate the mechanisms or sequence of the progression of the failure of the components. On the one hand this is well nigh to impossible because the numbers and complexity are staggering. On the other hand no attempt has been made to OUTLINE the sequence, a possible sequence. All that NIST seemed to feel obligated to do is try to demonstrate how X temp can push some element out of spec... ergo global collapse. Epic fail.
Anti NISTians are hopped up on faulting NIST's silly models. OK they deserve some amount of ridicule.
But we passed that station 5 years ago. Now where are we going?
Ironically any attempts at non NISTian models are ignored or derided with the reason being details don't matter.
Maybe... maybe not.
NIST fails in their attempt to come up with initiation scenarios and does not bother to carry them into the global collapse mode. And their JERF supporters can't or will not do it either... witness the responses to the thread Can a Single Column failure lead to Total Collapse... none of substance.
Problem
When something falls down... it loses the support which hold it together and keeps it standing. Or something takes that away or crushes it (a distinct change from the static state).
The over arching reason we are told is that heat renders the structure or nodes that hold it together below the performance profile to be self supporting.
We are told that structure have reserve strength... they do... which means that the normal operating stress is below the design stress. This is referred to as a factor of safety. For most this is only a concept which applies to the columns. This would be wrong.
Global/total collapses are not single causes... like a bomb blowing the thing up... but a series of failures of the components and nodes... thousands and tens of thousands of them... each one feed forward into a newly and less robust system.
The fog has been created by the failure of NIST and the anti NISTIans to articulate the mechanisms or sequence of the progression of the failure of the components. On the one hand this is well nigh to impossible because the numbers and complexity are staggering. On the other hand no attempt has been made to OUTLINE the sequence, a possible sequence. All that NIST seemed to feel obligated to do is try to demonstrate how X temp can push some element out of spec... ergo global collapse. Epic fail.
Anti NISTians are hopped up on faulting NIST's silly models. OK they deserve some amount of ridicule.
But we passed that station 5 years ago. Now where are we going?
Ironically any attempts at non NISTian models are ignored or derided with the reason being details don't matter.
Maybe... maybe not.
DGM
Skeptic not Atheist
You're always welcome to come up with your own. NIST's fits reasonably well with the events (JSanderO's is not bad except where we disagree on initiation).
"Truthers" have not come close to producing anything that even approaches a hypothesis. Why is this?
Are you basically saying that NIST should have continued running variations of the full collapse model, with different scenarios and model parameters, until they found a result that matched all of the external observables (including a brief "free fall" period for the upper exterior)?
I see several problems with that, starting with there being far too many model parameters to vary -- how do we know that the main cause of the differences between the modeled collapse and the observations wasn't the actual versus theoretical strengths of individual steel members, or slight dimensional differences between the blueprints and the as-build structure, or differences between the estimated and the actual loads per zone of floor, or any of dozens of other factors, any one of which could influence dozens to thousands of distinct individual quantities in the model inputs? We do not.
Perhaps that wouldn't matter so much, if they could do millions of runs; vary everything; do a genetic algorithm search. But, didn't each single run take months?
Okay, never mind that; marshall the nation's resources to do hundreds of runs at a time, decade after decade, until one is found to match... but does that that matching result now prove that all the inputs in that run are correct and the detailed chain of unobservable events produced in that run are what actually happened? No; it would likely be just one of astronomical numbers of possible matching results found, by scattershot searching, within a much vaster space of possibilities.
What, in the end, would be the point of all that? To confirm that letting a high-rise building burn for hours is a bad thing to be avoided... which we already know?
To rule out any possible scenario in which the same result could instead have been produced by controlled demolition using secret noiseless devices of unknown properties... which it couldn't possibly do?
There's no rationale to think that would be a good use of my tax money. Epic fail indeed.
Respectfully,
Myriad
jaydeehess
Penultimate Amazing
not entirely. The fire simulation program was another source. That simulation is a point of contention with the truth movement. Yet they seem to refuse to carry out one on their own.
True, but it is obvious that they would be relatively hot. Quantifying this might have been useful.
Ok, boiled down to few words, yes. Unfortunately its more than there is for the alternatives brought forth.
No one expects there to be. Not sure why you mention it.
This is a very odd comparison. The FDNY tour of WTC7 was in part to make sure there was no one inside. The report was that the FFs walked the entire length of the fifth floor, no fire at that time. We can assume the generator door was closed as that is the norm. We can assume it was not running as the louvers were closed. Did fire break out somewhere close to TT1 later in the day? There is no smoke or flames visible( no windows) that point to such an event.
It is possible, and I mentioned it years ago before the final report, that there was a fire and the smoke was being drawn up stairwells or elevator shafts, air being drawn in from below and, possibly through the slight gaps in the exhaust louvers. That would mask the existence from the outside. However, that is extremely speculative.
As for the 78th floor of WTC2 radio report, this is the only report from any fire involved floor in either building. It is also the lowest fire involved floor in either building. It represents the area hit by the tip of the port wing. It would be complete folly to expect that further inboard along that wing, where the fuel was, which hit higher floors, that the fires were equal in spread and intensity as they were on the 78th floor. I am surprised to see you infer it. Once again NIST utilized a fire spread computer simulation and compared visible fire spread to the computer predictions to arrive at a picture of probable interior conditions.
That is also what they did with the fires in #7.