Total Building Collapse from a Single Column Failure

[ozeco41]

....thanks for returning to the OP.

Thanks. Let's see if you can discuss your own OP.

The main problem is your habit of ignoring what is posted - and in this case making untrue assertions that I have not answered your questions. Despite the structure of those questions - ambiguous and leading as they were - you asked 11 questions and I gave you 11 answers. Here they are:

Your Question #1

NIST makes the case that the failure of column 79 on floor 13 apparently caused by a girder walking off its beam seat at column 79 led pretty quickly to the collapse of the entire building leaving nothing standing at all.

I wonder... how universal this actually is?

My answer was:

Well I doubt that it is universal at all for two sets of reasons:

...and I gave the reasons in detail.

Your Question #2

Would column 79 failing at floor 29 have caused the global collapse?

My answer was:

No - it was a major component of the collapse mechanism but the manner of its failing required other component failures. Changing the floor doesn't change the reality that the Col79 failure was only one component of the collapse mechanism.

Your Question #3

Would any other single column failing on any floor lead to global collapse?

My answer was:

Not likely. Risks becoming a strawman - the actual WTC7 collapse was not "caused" by Col 79 and Col 79 was not the initiator of its own failure. It didn't "lead" as in at head of chain - it followed some and came before others.

Your Question #4

Could any single column failing on any other floor NOT lead to global collapse?

My answer was:

Near certain it wouldn't as a stand alone event.

You then made a statement:

(I don't suspect the failure of a column at the roof level would.)

My comment was

Moot.

Your Question #5

If so why or why not?

My answer was:

Not a valid generic claim....would always be building structure specific.

Your Questions #6, #7, #8 and #9

Is this single column failure applicable to any multi story high rise? Would it have to be steel framed? Would it have to be a minimum building height? Would there have to be a minimum number of floors above the failed column?

My answer was:

All are false stated as they are as generic claims.

(Plus some advice which you choose to ridicule.)

Your Question #10

If the single column failure global collapse outcome is not more or less universally applicable what was it about 7 WTC's design and column failure at floor 13 that allowed for a single column failure to lead to global collapse?

My answer was:

This statement is not valid as a premise..therefore this:

Your Question #11

Should NIST have discussed this or not?

My answer was:

...is moot.

Eleven questions Sander. I answered all eleven. I am prepared to engage in discussion of those answers BUT your evasions and false claims need to stop.

If you don't want answers why ask the questions?

If you want to limit who answers why not try saying "Answers not wanted from ozeco because......"

You are fond of asking questions, ignoring the answers THEN shifting the goal posts by asking other unrelated questions - evasions or derails.

Why not simply respond to legitimate answers? So your concluding insult with this:

Don't beat around the bush. Answer the questions if you can. And skip the rubbish about generalities are always false.

Deserves a stronger put down -- but my polite rebuttal is:
1) I don't - you do.
2) I already have. Your innuendo that I cannot is offensive. Your inference that I have not is a lie.
3) If I choose to respond to your comments I will always discount false generalisations and any other false logic that stands in the way of understanding.

Ball in your court. Do you agree or disagree with my 11 answers to your 11 questions? I've stated them exactly as first posted. Several of the answers are wide open to legitimate comment. Go for it.

 

[JSanderO]

Here is my comment with reframed questions:

Obviously column 79 didn't cause the collapse. Its "failure" was some which enabled that which was supported by it to collapse.... and apparently NIST thought that other columns around 79 failed lickity split and that turned into what they call a global collapse.

A bunch of things when awry at / under col 79 and column 79 could not do its *normal job* and *caved* ... according the NIST... taking the entire building with it in a single column failure initiation explanation

Ergo: (1) Can a single column failure cause a high rise to collapse? Not the column... but its failure... not doing what it was designed to do..

(2) Does the location in elevation of the failed column have anything to do with global collapse?

(3) Could a single column failure in a *typical* grid of columns framed high rise suffer global collapse from a single column failure?

To learn lessons to be applied to other and buildings which was at least part of the NIST mission in its study one would expect them to have to identify the key weaknesses or failures modes.

In the case of 7WTC it appears that the mechanical damage from WTC was on the SW side and did not initiate even local failures above it. It may have caused fires, but this is actually not obvious either. The impaled steel on the WFC did not cause fires, nor at Bankers Trust.

I infer that the proximate cause of the global collapse was not the mechanical damage from 1WTC. Mechanical damage from WTC falling debris made less of the frame to collapse in 7WTC 7 hrs later.

The proximate cause (according to NIST's report) appears to be the fires and what they did to the steel, the connections and so forth over a 7 hr period. NIST seems to assert that it was heat from fire broke the camel's back at column 79 floor 13.

(4) Was the column 79 floor 13 location *special*?

It has been pointed out (by another poster in this thread) that column 79 was heaviest loaded column in the building. (That needs to be verified but it is not an unreasonable assertion). Surely the load of column 79 at grade was more than it was at floor 13.

(1) Can a single column's failure reliably lead to a global collapse in a typical steel frame high rise? (1a) If not, why not? (1b) If so, why so.

 

[Seymour Butz]

(1) Can a single column's failure reliably lead to a global collapse in a typical steel frame high rise? (1a) If not, why not? (1b) If so, why so.

Probably not. Cuz buildings are designed to redistribute loads if a single column fails, assuming that there is no other damage. Evidence of this is the fact that 1, 2, and 7 stood after having more than 1 column severed.

And really, this is a poor avenue to take, IMHO, if your goal is tide sign safer buildings. The circumstances that led up to not having any firefighting efforts in the building are unique but it is foreseeable that other circumstances could arise. So better firefighting systems, that don't put peoples lives at stake would be a better avenue.

Also, IMHO, you're off track in thinking that col79's failure was the initiator of the global collapse. It wasn't. The cascading failure of the floors around 79 was. Much better to figure out why THAT happened since we learned in the NIST report on 1 and 2 that those (typical?) floors could hold much more than one additional floor.

 

[ozeco41]

Probably not. Cuz buildings are designed to redistribute loads if a single column fails, assuming that there is no other damage. Evidence of this is the fact that 1, 2, and 7 stood after having more than 1 column severed.

And really, this is a poor avenue to take, IMHO, if your goal is tide sign safer buildings. The circumstances that led up to not having any firefighting efforts in the building are unique but it is foreseeable that other circumstances could arise. So better firefighting systems, that don't put peoples lives at stake would be a better avenue.

Also, IMHO, you're off track in thinking that col79's failure was the initiator of the global collapse. It wasn't. The cascading failure of the floors around 79 was. Much better to figure out why THAT happened since we learned in the NIST report on 1 and 2 that those (typical?) floors could hold much more than one additional floor.

All three points well stated Seymour Butz. 1 and 3 essentially the same ones I have made a few times in this thread. In discussions elsewhere with Sander I have also made your point #2. The priorities are 1 - provide escape for people and 2 (or lower) look after the building.

 

[jaydeehess]

Also, IMHO, you're off track in thinking that col79's failure was the initiator of the global collapse. It wasn't. The cascading failure of the floors around 79 was. Much better to figure out why THAT happened since we learned in the NIST report on 1 and 2 that those (typical?) floors could hold much more than one additional floor.

,, and we understand how that came to be as well. It was partially due to the odd arrangement of the beams contacting the girder which saw beams only on one side of that girder meaning there was no constraint to the beam expansion pushing on the girder.

That was on the one floor where the girder is hypothesized to have failed. However it would be noted that the floor below would also have seen elevated temps of its girder & beam system and they would have had less ability to take a load than in the pristine structure. Girder fails, floor fails and impacts next floor which has had its load bearing capability lessened and it can not withstand the dynamic load of the falling floor debris and it also fails leading to two floors worth of debris falling to yet the next floor down etc. Col 79, already at elevated temp at the region of failure of the girder is left with multiple levels of loss of lateral support on one side and buckles under its load, failing the floor systems along its length all the way to the roof. (at this point the structure will not succumb to global collapse BUT....) The resulting debris (some of which consists of the mechanicals located at the roof ) rains down on the lower levels impacting other load bearing members including, quite possibly, TT1, and its bolted connections.

 

[ozeco41]

All good thinking.

I've been trying to keep a very clear distinction between what we can assert as fact and what is speculation - admittedly some of it very highly plausible speculation but still open to other alternative explanations.

Which is why I still rank the NIST walk-off initiator as "speculation" alongside JSanderO's transfer truss initiator. And the possible plausible permutations can be many more.

And IMNSHO we will never be certain - and no-one has convinced me that the distinctions matter other than as individual personal curiosity. Which I understand and accept but it isn't grounds for further public expenditure on pointless won't go anywhere investigation.

All that IMNSHO as I have said.

 

[jaydeehess]

[qimg]http://conleys.com.au/smilies/thumbup.gif[/qimg]
All good thinking.

I've been trying to keep a very clear distinction between what we can assert as fact and what is speculation - admittedly some of it very highly plausible speculation but still open to other alternative explanations.

Which is why I still rank the NIST walk-off initiator as "speculation" alongside JSanderO's transfer truss initiator. And the possible plausible permutations can be many more.

And IMNSHO we will never be certain - and no-one has convinced me that the distinctions matter other than as individual personal curiosity. Which I understand and accept but it isn't grounds for further public expenditure on pointless won't go anywhere investigation.

All that IMNSHO as I have said.

One thing is certain, and its not actually part of this thread topic as far as I am concerned, and that is that there is more evidence that fire damage initiated, and contributed to, the progression to global collapse, than there is that any explosive or incindiary devices were surreptiously installed (before or on 9/11/01) and which then were used to initiate and cause global collapse.

 

[ozeco41]

One thing is certain, and its not actually part of this thread topic as far as I am concerned, and that is that there is more evidence that fire damage initiated, and contributed to, the progression to global collapse, than there is that any explosive or incindiary devices were surreptiously installed (before or on 9/11/01) and which then were used to initiate and cause global collapse.

Agreed - the real OP is:

...I wonder... how universal this actually is?

And that has two fatal flaws:
1) False premise that WTC7 was caused by Col 79 failure; and
2) False generalisations in both logic and in the structural aspects of single item causal failures.

So the topic is actually quite different from what really happened.

 

[Seymour Butz]

All three points well stated Seymour Butz. 1 and 3 essentially the same ones I have made a few times in this thread. In discussions elsewhere with Sander I have also made your point #2. The priorities are 1 - provide escape for people and 2 (or lower) look after the building.

Ok great. I quit reading your posts though cuz they've gotten too long winded

 

[Seymour Butz]

,, and we understand how that came to be as well. It was partially due to the odd arrangement of the beams contacting the girder which saw beams only on one side of that girder meaning there was no constraint to the beam expansion pushing on the girder.

That was on the one floor where the girder is hypothesized to have failed. However it would be noted that the floor below would also have seen elevated temps of its girder & beam system and they would have had less ability to take a load than in the pristine structure. Girder fails, floor fails and impacts next floor which has had its load bearing capability lessened and it can not withstand the dynamic load of the falling floor debris and it also fails leading to two floors worth of debris falling to yet the next floor down etc. Col 79, already at elevated temp at the region of failure of the girder is left with multiple levels of loss of lateral support on one side and buckles under its load, failing the floor systems along its length all the way to the roof. (at this point the structure will not succumb to global collapse BUT....) The resulting debris (some of which consists of the mechanicals located at the roof ) rains down on the lower levels impacting other load bearing members including, quite possibly, TT1, and its bolted connections.

I don't remember the temps being all that high on the lower floor supports and columns due to the intact fire proofing. If anything, I find it improbable that they got high enough to lessen strength much since, if I recollect correctly, fire proofing is applied to allow an area to " burn out " without the steel reaching the failure temps.

Perhaps only elevated temps are enough? I don't recollect anymore if steel loses strength through temp increase linearly or if there's a curve.

 

[Newtons Bit]

I don't remember the temps being all that high on the lower floor supports and columns due to the intact fire proofing. If anything, I find it improbable that they got high enough to lessen strength much since, if I recollect correctly, fire proofing is applied to allow an area to " burn out " without the steel reaching the failure temps.

Perhaps only elevated temps are enough? I don't recollect anymore if steel loses strength through temp increase linearly or if there's a curve.

It's a funny curve.

 

[ozeco41]

Ok great. I quit reading your posts though cuz they've gotten too long winded

No worry - not many people are interested in reasoned explanations these days - so you are not alone. The underlying problem remains however - If someone posts a medium length bit of nonsense it takes about 4-5 times that number of words to put it right. Part of the reason I long ago gave up responding to trolls. Not worth the necessary effort to rebut and playing "Whack-A-Mole" isn't my game.

I occasionally post a concise summary of FACT which can be briefer - see post 121 - and the following posts #121 and #123 with two members expressing appreciation. But sound LOGIC and reasoning takes more words if the arguments are to be both valid and bullet-proof.

 

[JSanderO]

Probably not. Cuz buildings are designed to redistribute loads if a single column fails, assuming that there is no other damage. Evidence of this is the fact that 1, 2, and 7 stood after having more than 1 column severed.

And really, this is a poor avenue to take, IMHO, if your goal is tide sign safer buildings. The circumstances that led up to not having any firefighting efforts in the building are unique but it is foreseeable that other circumstances could arise. So better firefighting systems, that don't put peoples lives at stake would be a better avenue.

Also, IMHO, you're off track in thinking that col79's failure was the initiator of the global collapse. It wasn't. The cascading failure of the floors around 79 was. Much better to figure out why THAT happened since we learned in the NIST report on 1 and 2 that those (typical?) floors could hold much more than one additional floor.

I am not off track because I DO NOT think column 79 was the straw that broke the camel's back. As you pointed out the twin towers each had multiple columns severed at stood after that so it wasn't a column failure which was the initiator... but it was a more likely that the columns that were remaining soon had their strength whittled down... and the floors collapsing and the frame gone kitty whampus and the ROOSD mass was created and that destroyed the tower.

As I suggest the proximate cause was more like the transfer truss which when THEY fail WOULD immediately involve multiple columns including 79, 80 and 81 under the center of the EPH...

So another question is:

Could the failure of TT#1 and or TT#2 cause the building to collapse?

 

[Animal]

Here is my comment with reframed questions:

Obviously column 79 didn't cause the collapse. Its "failure" was some which enabled that which was supported by it to collapse.... and apparently NIST thought that other columns around 79 failed lickity split and that turned into what they call a global collapse.

A bunch of things when awry at / under col 79 and column 79 could not do its *normal job* and *caved* ... according the NIST... taking the entire building with it in a single column failure initiation explanation

Ergo: (1) Can a single column failure cause a high rise to collapse? Not the column... but its failure... not doing what it was designed to do..

(2) Does the location in elevation of the failed column have anything to do with global collapse?

(3) Could a single column failure in a *typical* grid of columns framed high rise suffer global collapse from a single column failure?

To learn lessons to be applied to other and buildings which was at least part of the NIST mission in its study one would expect them to have to identify the key weaknesses or failures modes.

In the case of 7WTC it appears that the mechanical damage from WTC was on the SW side and did not initiate even local failures above it. It may have caused fires, but this is actually not obvious either. The impaled steel on the WFC did not cause fires, nor at Bankers Trust.

I infer that the proximate cause of the global collapse was not the mechanical damage from 1WTC. Mechanical damage from WTC falling debris made less of the frame to collapse in 7WTC 7 hrs later.

The proximate cause (according to NIST's report) appears to be the fires and what they did to the steel, the connections and so forth over a 7 hr period. NIST seems to assert that it was heat from fire broke the camel's back at column 79 floor 13.

(4) Was the column 79 floor 13 location *special*?

It has been pointed out (by another poster in this thread) that column 79 was heaviest loaded column in the building. (That needs to be verified but it is not an unreasonable assertion). Surely the load of column 79 at grade was more than it was at floor 13.

(1) Can a single column's failure reliably lead to a global collapse in a typical steel frame high rise? (1a) If not, why not? (1b) If so, why so.

In short yes. NCSTAR Vol.2 Sec 12.4.7 (Page 594) They ran a simulation without fire damage nor building damage, removing one section of the Col 79 between Floor 11-13 and the building structure failed.

 

[RenaissanceBiker]

The connections were obviously not strong enough to deal with the dynamic forces of a collapse.

We design connections to be strong enough to support ordinary static and dynamic loads. We do not normally design them to be strong enough to withstand such a catatrophic structural failure. If we did, every structural member would also be designed to resist such a load and every structure would end up being a doomsday vault (with the accompanying doomsday cost of construction).

/engineer

 

[Seymour Butz]

In short yes. NCSTAR Vol.2 Sec 12.4.7 (Page 594) They ran a simulation without fire damage nor building damage, removing one section of the Col 79 between Floor 11-13 and the building structure failed.

In a typical building?

I think not.

 

[Seymour Butz]

No worry - not many people are interested in reasoned explanations these days - so you are not alone. The underlying problem remains however - If someone posts a medium length bit of nonsense it takes about 4-5 times that number of words to put it right. Part of the reason I long ago gave up responding to trolls. Not worth the necessary effort to rebut and playing "Whack-A-Mole" isn't my game.

I occasionally post a concise summary of FACT which can be briefer - see post 121 - and the following posts #121 and #123 with two members expressing appreciation. But sound LOGIC and reasoning takes more words if the arguments are to be both valid and bullet-proof.

Brevity speaks volumes.

 

[Newtons Bit]

In a typical building?

I think not.

No, that's pretty typical. Typical steel buildings have no inherent resistance against column failure, it typically has to be designed in.

 

[Animal]

In a typical building?

I think not.

typical building.....as in typical structural grid.....no.......however the report gives a clue.......

From the NCSTAR 1-9 Vol.2

"The General Services Administration (GSA 2003) and the Unified Facilities Criteria (FC 2005) provide guidance for conducting a progressive collapse analysis for facilities with underground parking and/or uncontrolled public ground floor areas. However, the guidelines also recommend that buildings with generally unique or distinguishing structural features be evaluated for other scenarios where loss of a vertical support could lead to disproportionate damage. For WTC 7, Column 79 would have been a possible candidate for such an analysis, given it large tributary floor area of approximately 2000 Ft², had such guidance existed in the l980s."


Bolding mine.

 

[jaydeehess]

It's a funny curve.
[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_1632947e051936e249.jpg[/qimg][qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_1632948a21f7ed91a2.jpg[/qimg]

Having a bit of trouble reading that graph. Same graph twice, right?

Shows loss of 50% at 600C and approx 30% at ~450C.

My stainless steel wood stove Chimney is rated to withstand 2000F (1093 C)for one hour. Of course neither my woodstove or my chimney needs to carry almost no load. Point is that a wood fire can be expected to generate byproducts that, if ignited, can cause the chimney to reach over 1000 C. I have no trouble believeing that in a fire, the structural steel can reach at least the point at which the steel has lost 25-30% of its normal strength.

If that is a girder, and the girder seat at the column, and this girder has been moved such that it now has only a fraction of its normal contact area between girder and girder seat, its quite concievable that the girder flange and/or the girder seat fails.