Other WTC7 Investigations: Aegis Insurance v. 7 World Trade Company Expert Reports

[benthamitemetric]

Not many in the general public know too much about this particular litigation, but this case was one of many that the SDNY courts dealt with in the aftermath of 9-11. I previously researched the arguments and testimony in this case while looking for more insight into WTC 7's collapse. The case revolved primarily around a claim of negligence, with Aegis and others seeking to recover losses against 7 WTC Co. and others for what they alleged was negligent design and maintenance of WTC 7 that contributed to the collapse of that tower. The claimants ultimately lost that case--not because they were wrong that the WTC 7's design contributed to the failure, but because the court did not see any such alleged negligence as a proximate cause of the collapse given the unforeseeable intermediary cause of the events of 9-11.

Anyway, this post is not about the legal merits of the case, but instead it is about the expert reports connected therewith. When I previously researched the case, I had been unable to obtain those expert reports as the district court does not maintain them in their electronic database. A recent thread on ISF, however, made me realize that the reports were, in fact, still available. Instead of obtaining them from the district court, however, they needed to be bought through the 2nd circuit. Well, ~$60 later, my gift to this forum and all those interested in studying the collapse of WTC 7 is the full suite of Aegis's experts' reports (plus the declarations associated therewith). I haven't looked at them in too much detail as of the time of this post, but my cursory pass through revealed an abundance of information and analyses. Please find them all attached below. (They are large files, so thanks to Mick for offering to host them here!)

The reports as follows:

• Analysis of the Impact of a Fire in the Mechanical Room (5th & 6th Floor) of the World Trade Center 7 Building by Jose Torero.
• World Trade Center 7 by Joseph P. Colaco (same file as above)
• Response of WTC7 to Standard Office Fires and Collapse Initiation by Colin Bailey
• Expert Report by Frederick Mowrer
  
• Report and Summary of Findings: Global Collapse Analysis, World Trade Center 7 Investigation by Guy Nordenson (Report 1, Report 2)

EDIT: One thing I would urge readers of these reports to do, by the way, is to remember the context. These experts were hired by Aegis to make the best case for the failure and collapse of WTC 7 being the result of negligent design and/or maintenance. These reports were likely highly edited and tailored (in consultation with Aegis's litigation team) towards that end. That is not to say they are inaccurate or not representative of the thoughts and conclusions of the authors, but it is a reminder that they are not necessarily an unbiased analysis of all aspects of the collapse. (If there were any evidence that the tower was demolished deliberately, by the way, that would have been a much stronger claim--fraud--for Aegis to argue, so you can draw pretty strong inferences against them believing controlled demolition was a plausible hypothesis by them pursuing the negligence claim alone).

 

[econ41]

......
EDIT: One thing I would urge readers of these reports to do, by the way, is to remember the context. These experts were hired by Aegis to make the best case for the failure and collapse of WTC 7 being the result of negligent design and/or maintenance. These reports were likely highly edited and tailored (in consultation with Aegis's litigation team) towards that end. That is not to say they are inaccurate or not representative of the thoughts and conclusions of the authors, but it is a reminder that they are not necessarily an unbiased analysis of all aspects of the collapse. (If there were any evidence that the tower was demolished deliberately, by the way, that would have been a much stronger claim--fraud--for Aegis to argue, so you can draw pretty strong inferences against them believing controlled demolition was a plausible hypothesis by them pursuing the negligence claim alone).

Thanks - and belated congratulations o your extensive documentation of these matters.

The issue has once again become a topic of lively dispute on ISF. Sadly at the mediocre level of discussion that often happens. And the error/distortions of context are ram,pant.

Thanks for the links - some of us were having difficulty sourcing the Bailey material...the "truthers" misusing it were playing coy with presenting or linking the sources. Your post a day late. No problem tho.

Thanks again.

 

[MikeC]

Dollars to donuts some CT answer to this is that the insurance company is owned by TPTB so is part of the cover up, and these lawsuits are all fixed in advance........

 

[benthamitemetric]

Thanks - and belated congratulations o your extensive documentation of these matters.

The issue has once again become a topic of lively dispute on ISF. Sadly at the mediocre level of discussion that often happens. And the error/distortions of context are ram,pant.

Thanks for the links - some of us were having difficulty sourcing the Bailey material...the "truthers" misusing it were playing coy with presenting or linking the sources. Your post a day late. No problem tho.

Thanks again.

Thanks, econ41. I wish I could jump into the discussion on ISF, but for reason, no one has approved my account for posting after I registered. Oh well. In any event, the discussion there is really misguided. It has devolved into quibbling about whether the Bailey report alone somehow invalidates NIST's conclusions. But it seems no one has stepped back and considered the context of the report. Again, the experts were not tasked with figuring out the cause of the collapse per se; rather, they were tasked with figuring out and presenting the best possible arguments to support Aegis's legal theory of negligent design being the proximate cause of the collapse. That doesn't mean they are wrong or that their theory is invalidate, but it does mean their theory shouldn't simply be taken as a comprehensive analysis of all possible collapse scenarios. In fact, their expert reports were almost certainly edited in collaboration with highly seasoned litigators who would have removed analyses and information that did not support Aegis's case. Moreover, the discussion over there is ignoring that these reports are interconnected. You cannot, for example, understand the temperature assumptions in Bailey's report without reading Mowrer's report. Again, that is because these reports were designed to be presented as a highly-tailored persuasive set of arguments in support of a particular legal theory and, in order for them to be accepted by the court as such, each needed to be rooted in the opinion of an expert on its relevant subtopic (which would have not been possible in a compilation report that blurred the lines of attribution).

 

[benthamitemetric]

Not many in the general public know too much about this particular litigation, but this case was one of many that the SDNY courts dealt with in the aftermath of 9-11. I previously researched the arguments and testimony in this case while looking for more insight into WTC 7's collapse. The case revolved primarily around a claim of negligence, with Aegis and others seeking to recover losses against 7 WTC Co. and others for what they alleged was negligent design and maintenance of WTC 7 that contributed to the collapse of that tower. The claimants ultimately lost that case--not because they were wrong that the WTC 7's design contributed to the failure, but because the court did not see any such alleged negligence as a proximate cause of the collapse given the unforeseeable intermediary cause of the events of 9-11.

Anyway, this post is not about the legal merits of the case, but instead it is about the expert reports connected therewith. When I previously researched the case, I had been unable to obtain those expert reports as the district court does not maintain them in their electronic database. A recent thread on ISF, however, made me realize that the reports were, in fact, still available. Instead of obtaining them from the district court, however, they needed to be bought through the 2nd circuit. Well, ~$60 later, my gift to this forum and all those interested in studying the collapse of WTC 7 is the full suite of Aegis's experts' reports (plus the declarations associated therewith). I haven't looked at them in too much detail as of the time of this post, but my cursory pass through revealed an abundance of information and analyses. Please find them all attached below. (They are large files, so thanks to Mick for offering to host them here!)

The reports as follows:

• Analysis of the Impact of a Fire in the Mechanical Room (5th & 6th Floor) of the World Trade Center 7 Building by Jose Torero.
• World Trade Center 7 by Joseph P. Colaco (same file as above)
• Response of WTC7 to Standard Office Fires and Collapse Initiation by Colin Bailey
• Expert Report by Frederick Mowrer
  
• Report and Summary of Findings: Global Collapse Analysis, World Trade Center 7 Investigation by Guy Nordenson (Report 1, Report 2)

EDIT: One thing I would urge readers of these reports to do, by the way, is to remember the context. These experts were hired by Aegis to make the best case for the failure and collapse of WTC 7 being the result of negligent design and/or maintenance. These reports were likely highly edited and tailored (in consultation with Aegis's litigation team) towards that end. That is not to say they are inaccurate or not representative of the thoughts and conclusions of the authors, but it is a reminder that they are not necessarily an unbiased analysis of all aspects of the collapse. (If there were any evidence that the tower was demolished deliberately, by the way, that would have been a much stronger claim--fraud--for Aegis to argue, so you can draw pretty strong inferences against them believing controlled demolition was a plausible hypothesis by them pursuing the negligence claim alone).

Now that I have had more time to go through these, I should also add that there is a section of the Nordenson photographic analysis report that is included in the Mowrer report PDF. The way these PDFs were divided up is based on the way the court subdivided various filings and documents across the 16 volume record of filings provided from the district court case as part of the appeal process. Perhaps when I am back in the office next week and have easy access to more powerful PDF software, I will try to make more streamlined and intuitive report pdfs.

 

[econ41]

Thanks, econ41. I wish I could jump into the discussion on ISF, but for reason, no one has approved my account for posting after I registered...

My advice would be "Don't waste the effort!" If you havent recognised me - I post there as "ozeco41" - long ancient history reasons for the two posting names - no longer relevant - so I stick with the "Computer Doctor" avatar graphic to show who I am. Real identity not secret - follow the web site supporting many of my personal graphics.

The two main problems "over there" at ISF are confusions from "levels" - two aspects of levels:
A) The the first and probably the most obvious one is the wide range of levels of reasoning skill on display. When I get serious discussing these issues of process and meta process I often use a crude ranking scale. 1-2 for grade (primary) school level; 2-3 for High School; 3-4 for Undergraduate etc. The issues you identify are 3 or higher - understandable by High School students who may need it explained. Should be clear to graduates with some real world experience. The truther advocates are operating at 1-2 using bare assertions and blatant dishonesty. There is no effective way to address the issues when the "debunker" opponents post at levels 1-2-3 and the process problems - meta process in many cases - are at Level 4. And that is before we even get to the technical issue. So if you check my handful of posts I've deliberately framed the logic and discussion process errors in comments at levels 4-5. - long term plan to be on record. Over the heads of the two truthers.

The key issue is probably "Context" as you identify and in various modes - which leads to the second aspect of "levels" - the levels of technical system. So

B) Second issue of levels - Technical Level:
The "truthers" are explicitly arguing details without reference to context - level 1-2 reasoning at technical level 1 - details - and quote mined out of legitimate context.

The detail of "girder walk-off" which is not significant at technical level 2 or 3 - girder walk off is a component of the plausible NIST explanation. The bigger picture NIST explanation does not fail if the detail is falsified...it potentially could but proof is needed and the truthers have no proof.

And the predominant "debunker' responses are matching the "truther" claims - tit for tat at the same level - which does nothing other than guarantee discussion will not progress- it will circle.

So I'm letting it all happen. A few interventions in order to be "on record' if ever serious discussion takes place.

Oh well. In any event, the discussion there is really misguided. It has devolved into quibbling about whether the Bailey report alone somehow invalidates NIST's conclusions. But it seems no one has stepped back and considered the context of the report.

Exactly - the problem of context. Check my comments over there going back weeks in the current discussion series and years in my discussions with T Szamboti. context context context.

Again, the experts were not tasked with figuring out the cause of the collapse per se; rather, they were tasked with figuring out and presenting the best possible arguments to support Aegis's legal theory of negligent design being the proximate cause of the collapse. That doesn't mean they are wrong or that their theory is invalidate, but it does mean their theory shouldn't simply be taken as a comprehensive analysis of all possible collapse scenarios.

Fully understood - but I doubt that saying that "over there" would be comprehended by the "warring parties" - both sides. I'll sit back and let the dust settle.

Fully agree your remaining comments:

In fact, their expert reports were almost certainly edited in collaboration with highly seasoned litigators who would have removed analyses and information that did not support Aegis's case. Moreover, the discussion over there is ignoring that these reports are interconnected. You cannot, for example, understand the temperature assumptions in Bailey's report without reading Mowrer's report. Again, that is because these reports were designed to be presented as a highly-tailored persuasive set of arguments in support of a particular legal theory and, in order for them to be accepted by the court as such, each needed to be rooted in the opinion of an expert on its relevant subtopic (which would have not been possible in a compilation report that blurred the lines of attribution).

 

[tadaaa]

Thanks, econ41. I wish I could jump into the discussion on ISF, but for reason, no one has approved my account for posting after I registered. Oh well.

OT - but have had the same problem!!!!

Conspiracy???

 

[econ41]

OT - but have had the same problem!!!!

Conspiracy???

Yes. We don't want anyone who can think posting there. That rules both of you out until you have the brain lobotomy.

Seriously however - if either of you cannot get in via normal registration with or without email follow up - PM me the details and I'll PM the Admins from within ISF. I've done that for others in previous years.

 

[tadaaa]

Yes. We don't want anyone who can think posting there. That rules both of you out until you have the brain lobotomy.

Seriously however - if either of you cannot get in via normal registration with or without email follow up - PM me the details and I'll PM the Admins from within ISF. I've done that for others in previous years.

lol, that's very sweet of you econ41 (I think I did see your ISF name posting on the forum)

I did actually get an email from an Admin - when I queried my failed application - he suggested applying again, which I did

but like the OP, have heard nothing since

I will try again after xmas

 

[econ41]

lol, that's very sweet of you econ41 (I think I did see your ISF name posting on the forum)

econ41 == Eric Conley - work the 41 out for yourself. I was moderating on another significant forum when I joined JREF - so I changed user names for reasons no longer important. Hence "ozeco41" where the OZ bit should be obvious == AU

I did actually get an email from an Admin - when I queried my failed application - he suggested applying again, which I did

but like the OP, have heard nothing since

I will try again after xmas

Understood. There were a few staff changes at the admin level following the JREF>>>ISF move. The offer stays open.

 

[tadaaa]

OZ bit should be obvious == AU

don't tell anyone but I have dual UK/Kiwi citizenship

the offers stays open.

and thankyou

 

[econ41]

don't tell anyone but I have dual UK/Kiwi citizenship...

My sympathy on the Kiwi part. I'm 63/74ths de facto AU (11/74 UK) de jure AU for many years. Born Yorksha - coal miner grandfather.

I suppose you know the joke about the time the NZ Condom factory in Aukland was destroyed and the NZ prime munister esked for hilp from AU?
(Other members pls ignore the cross Tasman rivalry - its like the family loyalty bit. Many years ago there was some concern about the large numbers of Kiwis migrating cross Tasman to set up residence in Sydney. Someone asked the then NZ Prime Minister to comment. He said "if a lot are leaving NZ to move to AU that should improve the average IQ of both countries.)

and thankyou

No prob.

 

[benthamitemetric]

I spent a little more time going through these today and I have to say that the Nordenson report is quite interesting. He also independently modeled the collapse; however, unlikely Bailey, he modeled WTC globally. His actual model is described in the portions of his report in the second Nordenson report PDF in the OP. Section 4 (starting on pg 75 of that PDF) outlines the vulnerabilities he sees with the WTC structure, while Section 5 (Starting on page 115 of the pdf) describes the global collapse, and even includes very detailed diagrams of the likely collapse progression. These diagrams are the sort of thing I wish NIST had produced more of in relating their theory of the collapse. He has a pretty clear explanation as to how he believes the inner supports failed prior to the collapse of the outer frame.

 

[Landru]

I spent a little more time going through these today and I have to say that the Nordenson report is quite interesting. He also independently modeled the collapse; however, unlikely Bailey, he modeled WTC globally. His actual model is described in the portions of his report in the second Nordenson report PDF in the OP. Section 4 (starting on pg 75 of that PDF) outlines the vulnerabilities he sees with the WTC structure, while Section 5 (Starting on page 115 of the pdf) describes the global collapse, and even includes very detailed diagrams of the likely collapse progression. These diagrams are the sort of thing I wish NIST had produced more of in relating their theory of the collapse. He has a pretty clear explanation as to how he believes the inner supports failed prior to the collapse of the outer frame.

Are you trying to make a point? If so please state what it is and provide evidence.

 

[econ41]

I spent a little more time going through these today and I have to say that the Nordenson report is quite interesting. He also independently modeled the collapse; however, unlikely Bailey, he modeled WTC globally. His actual model is described in the portions of his report in the second Nordenson report PDF in the OP. Section 4 (starting on pg 75 of that PDF) outlines the vulnerabilities he sees with the WTC structure, while Section 5 (Starting on page 115 of the pdf) describes the global collapse, and even includes very detailed diagrams of the likely collapse progression. These diagrams are the sort of thing I wish NIST had produced more of in relating their theory of the collapse. He has a pretty clear explanation as to how he believes the inner supports failed prior to the collapse of the outer frame.

Thanks. I'll read it over the next few hours.

 

[benthamitemetric]

Are you trying to make a point? If so please state what it is and provide evidence.

Just making a note on where others could find the analysis of the collapse scenario as it seems to pertain to the most frequently discussed aspect of the collapse (whether global failure could be induced from a single point and whether it could progress without much visual movement of the moment frame). I was actually trying not to make a point as to its correctness as I have not had a chance to compare it to NIST's analyses or any other particularly set of claims about the collapse. Please feel free to delete that message and this one if you feel that type of note is too vague for Metabunk's purposes from an argumentative standpoint.

 

[Landru]

Just making a note on where others could find the analysis of the collapse scenario as it seems to pertain to the most frequently discussed aspect of the collapse (whether global failure could be induced from a single point and whether it could progress without much visual movement of the moment frame). I was actually trying not to make a point as to its correctness as I have not had a chance to compare it to NIST's analyses or any other particularly set of claims about the collapse. Please feel free to delete that message and this one if you feel that type of note is too vague for Metabunk's purposes from an argumentative standpoint.

All that is being asked is that you provide a link so people don't have to hunt around. Also, share the point you are trying to make. This is not a debate forum. The posting guidelines spell all of this out.

 

[benthamitemetric]

Understood. Thanks, Landru.

I should also note for posterity that I have emailed a link to this site to Prof. Hulsey and his research assistants Zhili Quan and Feng Xaio in the hope that the analyses in these reports will aid them in their current study.

EDIT: And I received a quick and kind reply from Mr. Xaio stating they would study the reports. Godspeed and best wishes to the University of Alaska WTC7 study team!

 

[Polly Math]

A comparison between this and NIST's analysis would seem inevitable. ARUP is far superior analysis both in terms of the greater use of temperature dependent elements, but also in the way that the sub model events are collated into the 4 case models.
I would prefer to have seen a more specific justification as to the flute gap and trench wall issues that existed around the girder that failed.

 

[econ41]

A comparison between this and NIST's analysis would seem inevitable.

Without doubt. The discussion I have seen to date has been on polarised "truther" v "debunker" contexts. Arguably neither NIST nor ARUP were targeted at that context tho' NIST's work was for piublic consuntion. The issue is whether or not the comparisons are/will be valid. And that requires definition of purpose or objectives - no point asserting that either is somehow superior without addressing the question "Superior for what purpose?" Is ARUP's superior for NIST's purpose? Both ARUP and NIST appear to have met their respective client's very different requirements.

I doubt that either had Internet Forum discussions as their primary target.

 

[Polly Math]

"Superior for what purpose?" Is ARUP's superior for NIST's purpose? Both ARUP and NIST appear to have met their respective client's very different requirements.

I doubt that either had Internet Forum discussions as their primary target.

This is FEA Vs FEA. ARUP accessed a whole host of drawings that NIST did not have to hand prior to 2008. These confirmed shear studs and end plates on the girder. Elements that NIST had not confirmed, so not included in their model. ARUP also did a very good job of modelling the floor system, down to the inclusion of the wire mesh.
I would imagine that ARUP must have ran a simulation with NISTs temperatures applied to the elements. At the very least Torero will have, given his position at the CTBUH at that time.
The NIST story of the girder failing in the heating phase was always difficult to accept for me. A failure in the cooling phase does however look more of a possibility. The ARUP analysis doesn't disprove NIST, but rather endorses their stated alternative mode of failure for the girder ie due to contraction of NE beams. It does however, ask some serious questions as to the accuracy with which NIST modeled the connection. I would say that drawing availability looks like the culprit. NIST were as accurate as they could be with the information that they had at the time.

 

[econ41]

Thanks - now I comprehend where you are coming from.

My queries were directed at the higher level issues of purpose - which are still relevant. But not at technical level direct comparison.

This is FEA Vs FEA. ARUP accessed a whole host of drawings that NIST did not have to hand prior to 2008. These confirmed shear studs and end plates on the girder. Elements that NIST had not confirmed, so not included in their model. ARUP also did a very good job of modelling the floor system, down to the inclusion of the wire mesh.

That is broadly the same as my understanding.

I'm aware of a recent "spurt" of interest in polarised "truther" v "debunker" discussions on a couple of other forums. At this stage of conspiracy related discussion the remaining few "truth movement" activists are focussed on discrediting NIST and have been misrepresenting ARUP et al for that purpose. Reality in my opinion - seems same as yours - both NIST and ARUP offer plausible "big picture" alternatives with some differences in details.

I would imagine that ARUP must have ran a simulation with NISTs temperatures applied to the elements. At the very least Torero will have, given his position at the CTBUH at that time.

That is my understanding.

The NIST story of the girder failing in the heating phase was always difficult to accept for me. A failure in the cooling phase does however look more of a possibility.

I've never needed to take NIST as literal at that level. "Walk-off" is a likely scenario - whether it involves one single or several cycles of movement. And single vector "push" or "pull" not likly - bending and twisting as well as displacement in one or two directions more likely. Plus it was not single item failure. The scenario had to involve multiple levels of removed bracing for that column to fail.

My interest in WTC 9/11 collapses goes back to 2007 - a long story - and my focus on explaining the mechanism of collapse of the Twin Towers. I've personally not given much attention to WTC 7 - it was much easier to be sure of WTC1 & 2 collapses - the engineering of WTC7 much more speculative.

The ARUP analysis doesn't disprove NIST, but rather endorses their stated alternative mode of failure for the girder ie due to contraction of NE beams. It does however, ask some serious questions as to the accuracy with which NIST modeled the connection. I would say that drawing availability looks like the culprit. NIST were as accurate as they could be with the information that they had at the time.

And good enough for their client at the time.

The politics of the two are vastly different - ARUP no holds barred on possible poor aspects of design. No need for NIST to emphasis those matters and arguable imprudent to do so.

 

[Polly Math]

Politics doesn't come into FEA. It does intrude on the opinion though.
All in all, NIST did not too badly. They more or less had the initiating event at floor 13 down to 2 possibilities. Their 2nd choice would appear to have been correct. I imagine they will regret not continuing their simulation, having not deemed the girder to have failed so early on. Looks very much like it would have failed on the cooling stage.
There's lessons learned exercises to be done at NIST re incomplete data etc, but all in all, to get the cause down to 2 possibilities in an unprecedented type of investigation into an unprecedented type of event isn't too shabby.

 

[econ41]

Politics doesn't come into FEA.

Your opening comment was "A comparison between this and NIST's analysis would seem inevitable." - and the comparisons will mostly occur in two arenas.
(A) "Public" discussion related to conspiracy theory; AND
(B) Professional discussion of the FEA comparisons.

The political setting for "A" is obvious. But it is potentially real for "B" also.

It does intrude on the opinion though.

Yes.

All in all, NIST did not too badly. They more or less had the initiating event at floor 13 down to 2 possibilities. Their 2nd choice would appear to have been correct. I imagine they will regret not continuing their simulation, having not deemed the girder to have failed so early on. Looks very much like it would have failed on the cooling stage.

Agreed and probably a good insight.

There's lessons learned exercises to be done at NIST re incomplete data etc, but all in all, to get the cause down to 2 possibilities in an unprecedented type of investigation into an unprecedented type of event isn't too shabby.

Which takes us back to my first comments. It was fit for purpose - remember that explaining the 9/11 event collapses was only one of NIST's 4 objectives. The "safety of future buildings" focus of the other three was arguably more important.

 

[Polly Math]

Agreed and probably a good insight. Which takes us back to my first comments. It was fit for purpose - remember that explaining the 9/11 event collapses was only one of NIST's 4 objectives. The "safety of future buildings" focus of the other three was arguably more important.

The engineering goal in high rise steel construction is to have a structure that can be left to burn out, without the prospect of collapse. This was clearly not the case with WTC7 and it is crucial to know the phase that the failure occurred in.
It is all too easy to be wise after the event, but it seems obvious now that the cooling phase should have been investigated more fully by NIST. The questions posed to them about this by the CTBUH certainly make more sense in light of these reports.
If the questions re plates, studs, cooling phase failure etc had been properly addressed by NIST at the consultation period, their analysis may have been better enough informed to have seen that the girder cannot pass the column west plate in the heating phase. This would have seen the analysis continue into the cooling phase.
NIST were not fit for purpose. They failed to take on board the questions asked within the public consultation period which turned out to be valid, and had a serious impact on the analysis results when taken into account. In fairness to NIST, their investigation perhaps did much of the heavy lifting for ARUP. The details that ARUP included though, do seem to have had a material effect on how the failure could have occurred.
If NIST had analysed the cooling phase closer, their investigation would better have informed future building safety.

 

[Jeffrey Orling]

The engineering goal in high rise steel construction is to have a structure that can be left to burn out, without the prospect of collapse. This was clearly not the case with WTC7 and it is crucial to know the phase that the failure occurred in.
It is all too easy to be wise after the event, but it seems obvious now that the cooling phase should have been investigated more fully by NIST. The questions posed to them about this by the CTBUH certainly make more sense in light of these reports.
If the questions re plates, studs, cooling phase failure etc had been properly addressed by NIST at the consultation period, their analysis may have been better enough informed to have seen that the girder cannot pass the column west plate in the heating phase. This would have seen the analysis continue into the cooling phase.
NIST were not fit for purpose. They failed to take on board the questions asked within the public consultation period which turned out to be valid, and had a serious impact on the analysis results when taken into account. In fairness to NIST, their investigation perhaps did much of the heavy lifting for ARUP. The details that ARUP included though, do seem to have had a material effect on how the failure could have occurred.
If NIST had analysed the cooling phase closer, their investigation would better have informed future building safety.

Are you satisfied that in these studies that the progression to global collapse was seemingly ignored as far as I can tell. Sure we can see a causal relationship between the collapse of the EPH and col 79 and 80 below it. But that was followed by the collapse of the WPH... why weren't explanations provided as to how the columns beneath it became involved? Is that meant to be "self evident"?

What about an explanation for the kink and the counter clockwise rotation is the collapse of the moment frame of the perimeter? Should we get an explanation to explain this as part of the explanation of the collapse or simply the failure of a single girder at a single column is sufficient?

 

[Polly Math]

Are you satisfied that in these studies that the progression to global collapse was seemingly ignored as far as I can tell. Sure we can see a causal relationship between the collapse of the EPH and col 79 and 80 below it. But that was followed by the collapse of the WPH... why weren't explanations provided as to how the columns beneath it became involved? Is that meant to be "self evident"?

What about an explanation for the kink and the counter clockwise rotation is the collapse of the moment frame of the perimeter? Should we get an explanation to explain this as part of the explanation of the collapse or simply the failure of a single girder at a single column is sufficient?

The progression to global collapse wasn't modeled by ARUP, but rather only the initiating event, which I think they did a good job of analysing. The SAP2000 model that Nordenson uses to calculate the potential and dissipated energy by the falling floor does not look as accurate.
I wouldn't take any of these analysis as satisfactory in terms of demonstration of progression from damage to global collapse. Remember too, that these guys exist in a very small world academically. there is politics in the opinion, but not the analysis. Bailey especially is lenient on NIST, but still contradictory.

 

[Jeffrey Orling]

I think that one of the main things which "freaked" people out was the failure of the buildings to stand... that is arrest or isolate whatever failures were caused by the planes in the case of the twin towers and the fires etc. for all three. They see the towers standing after the planes hit them and so in my opinion NIST dropped the ball by not shedding more light on how they PROGRESSED (as the result of unfought fires) to global collapse in 15 seconds. I suspect in the mind of the public... this makes no sense...

Perhaps the same sort of fog remains with the 7wtc studies... Is the public to assume that a failure of a single column leading to a local floor collapse can result in the entire building collapsing in less than 15 seconds? Apparently that IS what happened. No denying that. My sense is that the after reports needed to shed light on why and how the fires caused global collapse... And is any steel frame vulnerable to the same? If not, why not?

I think the take away may be pretty frightening for many... if global collapse is a likely possibility for un fought office fires in high rise steel frames... what can be done... to mitigate this... if anything... And if there are retro fits... does it make sense? Is it too expensive? Does it come down to a cost benefit risk analysis?

And then there are examples of other building fires without "global collapse" which is reassuring. But what are the differences which allowed those buildings to stand and the WTC ones to collapse? I ask this because this is what I think the public expected and why many feel the NIST reports seemed like an obfuscation.

Do you think the after reports... including ARUP removes this fog?

 

[Oystein]

Are you satisfied that in these studies that the progression to global collapse was seemingly ignored as far as I can tell. Sure we can see a causal relationship between the collapse of the EPH and col 79 and 80 below it. But that was followed by the collapse of the WPH... why weren't explanations provided as to how the columns beneath it became involved? Is that meant to be "self evident"?

What about an explanation for the kink and the counter clockwise rotation is the collapse of the moment frame of the perimeter? Should we get an explanation to explain this as part of the explanation of the collapse or simply the failure of a single girder at a single column is sufficient?

Read Nordenson's report, 2nd PDF, Section 5.8 "Probable Collapse Sequence Stage 5 Analysis Details" starting on page 103 (page 153 of the PDF file).

...Figures 5.33a and 5.34. These figures illustrate that the buckling of the lower northeastern corner of the perimeter frame in Stage 4 causes the unbraced eastern half of the building to sway northward. The deformed shape closely resembles the visual evidence of the "kink" in the north façade of the building immediately preceding total collapse of the building (Figure 5.33b).

There's your "explanation for the kink and [a part of] the counter clockwise rotation".

...the floor areas tributary to Columns 76, 77 and 78 have greater connectivity to the adjacent structure. Furthermore, the mass of the large tributary areas is greater. As the eastern supports of these areas fail, each floor level rotates about its remaining western support, creating a centripetal force that imposes tension on the rotating floor (Figure 5.35). The horizontal component of this tensile force in turn applies an eastward pull on each floor to the west (Figure 5.36).

The explanation that follows as a bit too complicated to reproduce in full - make sure to read it yourself. I am construing this a the centipetal force, resulting from floor slabs rotating around their western connection on columns 73-75 as they fall with col 76-78, and creates a lateral load on the remaining, western, core columns to make them fail close to simultaneously. That's "how the columns beneath [the WPH] became involved".

 

[Jeffrey Orling]

Oy, Thanks.. I am thinking that the plan form itself might have led to the counter clockwise twist... the first quote you cited doesn't xplain why it sways northward and not south for example... but if the sequence of collapse on that east side begins in the NE maybe the rest is pulled toward it with the west being more rigid so it lags behind?

 

[Oystein]

I think that one of the main things which "freaked" people out was the failure of the buildings to stand...
...
I think the take away may be pretty frightening for many... if global collapse is a likely possibility for un fought office fires in high rise steel frames... what can be done... to mitigate this... if anything... And if there are retro fits... does it make sense? Is it too expensive? Does it come down to a cost benefit risk analysis?

And then there are examples of other building fires without "global collapse" which is reassuring. But what are the differences which allowed those buildings to stand and the WTC ones to collapse? I ask this because this is what I think the public expected and why many feel the NIST reports seemed like an obfuscation.

Do you think the after reports... including ARUP removes this fog?

None of the reports was written with laypeople's fears at the forefront of objectives. They were written for engineers, developers, law makers, code authors, courts and legal parties, all supposedly qualified in their fields.

The common wisdom seems to be that the proper way to keep a building from collapsing progressively and totally is to prevent local collapses in the first place. Once you allow for local collapses to be inside the envelope of design objectives, where do you stop?

Yes, buildings can collapse totally. When they are tall, they will collapse fast if and when they collapse. Every reasonable building with space for humans is vulnerable to collapse, total collapse, from some initiating event. All you can design for is foreseeable events, and the most you can achieve is to allow humans to evacuate in time before collapse ensues. You can debate what the limits of "foreseeable" are, and you can look at smarter ways to design against those foreseeable attacks, but you cannot reasonably hope to make every building safe from every possible event.

 

[Jeffrey Orling]

None of the reports was written with laypeople's fears at the forefront of objectives. They were written for engineers, developers, law makers, code authors, courts and legal parties, all supposedly qualified in their fields.

The common wisdom seems to be that the proper way to keep a building from collapsing progressively and totally is to prevent local collapses in the first place. Once you allow for local collapses to be inside the envelope of design objectives, where do you stop?

Yes, buildings can collapse totally. When they are tall, they will collapse fast if and when they collapse. Every reasonable building with space for humans is vulnerable to collapse, total collapse, from some initiating event. All you can design for is foreseeable events, and the most you can achieve is to allow humans to evacuate in time before collapse ensues. You can debate what the limits of "foreseeable" are, and you can look at smarter ways to design against those foreseeable attacks, but you cannot reasonably hope to make every building safe from every possible event.

I don't know if this is true. The NIST study was authorized by congress. It was not undertaken by the a professional engineer society. Sure technical recommendations regarding life safety were the concern and these would be written by technical experts.. who write Building Codes.

Not every building is subject to complete collapse from local failure. That statement is completely without basis in fact.

Obviously high rises being stacked up are more vulnerable to global collapse... but designs can mitigate and isolate local failures perhaps vertical and laterally (plan form).

The column free hull and core plans may be more vulnerable to global collapse. These are built for one reason... economy. Once they get a threshold level of failure... seems as if the building is doomed. No?

 

[Polly Math]

Do you think the after reports... including ARUP removes this fog?

In a word, no. Torero would be the guy I would like to speak to out of all the experts in relation to this. His previous work on predictive fire systems for buildings left him well placed to speak more on progression. ARUP cleared up some fog around the initiating event, but not around the progression to global collapse.
As for Nordenson, , there's a few interesting points raised, and a lot of "ifs" and "buts". The model he uses to gauge potential and impact energy from falling floors is "interesting" let's say.
All in all there is more compliance than defiance in these reports.

 

[Jeffrey Orling]

In a word, no. Torero would be the guy I would like to speak to out of all the experts in relation to this. His previous work on predictive fire systems for buildings left him well placed to speak more on progression. ARUP cleared up some fog around the initiating event, but not around the progression to global collapse.
As for Nordenson, , there's a few interesting points raised, and a lot of "ifs" and "buts". The model he uses to gauge potential and impact energy from falling floors is "interesting" let's say.
All in all there is more compliance than defiance in these reports.

This is an excellent comment... and underlies my frustration with these reports and with all the internet discussions over the years... Net warriors may be ill equipped to drill down into such complex matters.. as progressive systems failures in buildings. But there seems to have been a side stepping of some of the big questions... in my mind... about high rise vulnerability to complete collapse.

When the issue is treated as let's kill the fire before it gets out of control and let's get the people out in X minutes... it doesn't address what happens when it is out of control. Should arrest and isolation be a design objective?

 

[Oystein]

...
Not every building is subject to complete collapse from local failure. That statement is completely without basis in fact.
...

I didn't say "from local failure".

One could argue that the failures in the WTC towers weren't strictly local:
In the twins, damage apparently cumulated over several floors, many columns, many joists on the the affected floors. The initial impacts already cut a lot of columns. I think you agree.

So let's talk about #7: It seems that the consensus is that cutting col 79 somewhere low is likely to initiate total collapse, but in all the models, it was floor failure over several stories that made 79 buckle. It seems less obvious that some one girder connection alone, without the addictional damage that had also accumulated over time, would have sufficed to start the cascade of floor failures that left col 79 fatally unbraced. In the NIST model, several other connections - most significantly the c77-80 girder connection failure on c80, fl14, had initiated its own cascade - had failed or were damaged before c79-44 fell. In the ARUP and Nordenson models, I am not sure how far they went with the dynamic simulation resulting from the c79-44 pull-off.

Connection failures on several floors isn't that local, and perhaps none ought to have happened in the first place. Then again, the designers did not, and could not have been expected to, foresee that fires would start on several floors (or spread between floors that had their fire stops compromised) and have the benefit of sprinklers not working and fire department lacking capacity. The building stood the required 3 hours, a time within which some firefighting ought to have begun, or all bets are off anyway.

 

[Jeffrey Orling]

Oy.... a few points and it may be semantics...

What is local? A few sections of a few floors would be local to me... but maybe this is not to you? Clearly when you have fire it is organic and spreads and will involve more and more of the building without effective mitigation like fire stops... and so forth open office plans by their very nature enable fire spread throughout a floor. You don't disagree do you? Same with open stairs connecting one floor to another. Vertical shafts are another path for flame spread... as are the gaps between the slabs and the skin of the building.

The fact is that the twins survived the local mech damage from the planes... and without fire likely would still be standing. The fires spread because there was ineffective fire mitigation in design and practice. You realize of course that the original design did not include sprinklers! Ha?????????????

 

[Oystein]

Yes, it's semantics - there is a continuum from strictly local (one element fails and all else remains pristine) to complete and total. There isn't a line that you can reasonable draw to describe what is "local" in any part of every building.

As fires spread ... think this to its logical conclusion were a local fire with local damage over time affects the entire building with "local" damages everywhere.

 

[Jeffrey Orling]

Yes, it's semantics - there is a continuum from strictly local (one element fails and all else remains pristine) to complete and total. There isn't a line that you can reasonable draw to describe what is "local" in any part of every building.

As fires spread ... think this to its logical conclusion were a local fire with local damage over time affects the entire building with "local" damages everywhere.

So let's be a bit arbitrary or "rational" and try to define how much destruction from whatever cause would be considered "local". I consider the damage from the planes to be local... the gash in 7wtc to be local. I consider multi floor fires to be local. I even consider the collapse of the floors to the NE of col 79 to be local over a few floors.

Global to me is when the entire building is collapsing...

But sure lots of locals become a global!

 

[Polly Math]

Net warriors may be ill equipped to drill down into such complex matters.. as progressive systems failures in buildings. But there seems to have been a side stepping of some of the big questions... in my mind... about high rise vulnerability to complete collapse.

Who is equipped to demonstrate an understanding of progressive collapse of a high rise steel building? The unprecedented nature of the collapse requires an analysis that would turn conventional fire engineering thinking on its head. I don't see any such thing here. If Torero in particular could have demonstrated this in a FEA, I am sure he would have done so long before the AEGIS court case. And if Torero cannot, then neither can NIST.
I don't think there is any side stepping going on as such by any of these experts. They were posed a question that assumed NISTs initiating event would lead to a progressive collapse, and they produced analysis and opinion that reflected this assumption.

When the issue is treated as let's kill the fire before it gets out of control and let's get the people out in X minutes... it doesn't address what happens when it is out of control. Should arrest and isolation be a design objective?

The conventional thinking of ARUP, NIST and anyone else in the fire sciences arena is that a steel framed building experiencing a worst case scenario fire, should be able to be left to burn out completely without fear of collapse. This was always conventional thinking, and WTC7 doesn't change that as remaining the underpinning principle and rule for high rise steel design.
Many fire science innovations begin life at Edinburgh University, "fire grid" being a prime example of this. If anybody was going to come up with a plausible analysis that showed a single initiating event leading to progressive global collapse, they would have done it.
It's off topic, but if it is of interest, you can hear Prof. Torero speaking about fire grid and other innovations from Edinburgh here,

 

[Mick West]

Sorry guys, there's such a lot of material in these reports that this is destined to be an endless thread. Please start individual threads for individual topic, with regard to the posting guidelines. If you want to have an endless discussion, then you know there are other forums more appropriate for that.

Girder stiffness discussion moved to:
https://www.metabunk.org/does-the-e...tions-demonstrate-anything.t7185/#post-173554