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OOS Collapse Propagation Model

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That's why we have mandatory fire suppression (sprinklers). Your making excuses for substandard workmanship. It's not hard to do it right. It's also not hard to make sure no one compromises it down the line, it's call using qualified contractors.

Do you think the towers could not deal with a normal fire? They did you know.

The design of floors in high rise is based on the assumption that the sprinkler system may fail. Or put in another way the fire protection is there in case the sprinklers fail.

I am not making excuses for substandard work but if you have ever seen a fire protection guy trying to spray a no 4 bar you would not be saying it is not hard. I would say its impossible.

Once you have some overspray on the bar it's nearly impossiBle to measure thickness without a gage measurement.

And if you think that a qualified ventilation contractor looks after sprayed fire protection then you must be nuts
 
I am not making excuses for substandard work but if you have ever seen a fire protection guy trying to spray a no 4 bar you would not be saying it is not hard. I would say its impossible.


And if you think that a qualified ventilation contractor looks after sprayed fire protection then you must be nuts


You need to find better subs. :(

It's like having an electrician that can fish a wire anywhere with no wall/ceiling damage to the guys that poke holes everywhere. Competent contractors do it right.
 
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You need to find better subs. :(

It's like having an electrician that can fish a wire anywhere with no wall/ceiling damage to the guys that poke holes everywhere. Competent contractors do it right.

Yes but it should be more expensive. Firstly more expensive to spray, because it's 10 times more difficult to spray bars rather than beams. And much more care needs to be taken in looking after it.
 
Yes but it should be more expensive. Firstly more expensive to spray, because it's 10 times more difficult to spray bars rather than beams. And much more care needs to be taken in looking after it.
Compare that to the cost of steel and other associated costs. Mostly the weight penalty, fabrication and installation over the whole structure. Make sense to have the fire guys take their time and do it the way the engineers want.
 
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Compare that to the cost of steel and other associated costs. Mostly the weight penalty on the whole structure.

Glad I don't work in your buildings then!

I think we have reached an impasse. See you next week for more exciting adventures on JREF.
 
Glad I don't work in your buildings then!

Hey, I give the engineers what they asked for. It's what I (and all my contractors) do. :)

ETA: We (and a lot like me) belong to a club we like to call "code +". Over-kill is not a bad thing and most of the time has little to no effect on our bottom line. Build it better is my motto.
 
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We specify things for a reason. It's the sub's job to do it the way we want it.
Just as when I specify a -7 titanium Hi-lite, I don't accept a -6 Aluminum rivet...
Do it right. Or you're fired.
 
Yes but it should be more expensive. Firstly more expensive to spray, because it's 10 times more difficult to spray bars rather than beams. And much more care needs to be taken in looking after it.

There are assemblies other than spray on FRM. And in some types of construction, the joists and deck are pre-assembled before lifted into place, these assemblies could already have the protection applied with easier application methods.
 
This is the statement given by Ms. Regenhard of the Skyscraper Safety Campaign in a congressional session on the NIST WTC investigation:


From these comments certain key words and phrases can be extracted:

politically correct
avoidance of blame
handled gingerly
no one wants to put anyone on the line
no one wants to look into...
skirted around
tiptoeing through the tulips
not taking a stand
abomination
a sin
an outrage against humanity
should have been investigated
sort of dealt with in a friendly basis



My guess is that she had no idea at the time of what we now sometimes call ROOSD.

My research has verified that her observations hit the mark perfectly.



As a follow-up, it would be interesting to know if the most prominent members of the Skyscraper Safety Campaign are aware of what we call ROOSD. Sander, I believe you mentioned commenting on this subject to James Quintiere, is that true?

Does anyone believe that Ms Regenhard, surviving parent of a deceased firefighter and co-chair of the Skyscraper Safety Campaign, should be given a clear, unambiguous description of the actual collapse modes of WTC1 and 2?

Within this environment there is an inability to approach the written record of the collapses in a critical way. Offocial = good and wise. All confusion about the collapses is believed to be due to 'truthers' or the 'ignorant laymen in the public'.

The NIST, ASCE or JEM are responsible for....nothing.

I attended a seminar at John Jay College a number of years ago at the Christian Regenhard Center. Quintierre, Ms Regenhard, Prof. Glenn Corbett were among those who attended. The seminar was to examine the response and investigation of NIST. They looked at official responses to large fires in the past, egress issues and so on.

They did not discuss engineering at all. I had the honor to speak with a few of the presenters including Quintierre and Ms Regenhard (She did not present)... and did an overview to Quintierre about ROOSD. He was interested but said he was not an structural engineer and not competent to evaluate its veracity. We corresponded a bit after that.

My take away from this seminar... (NOT a truther sponsored one) was that the presenters were not satisfied with how NIST conducted the investigation... and felt it was a "fail" not in the report content (not examined there), but in how they conducted the investigation. The content of the NIST report was not under scrutiny. If you don't properly conduct a disaster investigation... you can't get the best results.

This was not about truther or official claims... but about how the investigation itself was carried out. It was pretty telling because Quintierre l believe left NIST over this matter because he advocated the use of protocols similar to what the NTSB does in plane crash investigations. It was not clear that presenters believed that NIST intentionally bungled anything. None of them seemed pleased with what they did though.

I was hoping that NIST would have been present. They sent no reps as far as I could tell.

AE911T (inappropriately) set a table to *lobby* attendees .
 
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An article about James Quintiere and his thoughts on the NIST investigation is linked here.


Quote:

"James Quintiere, Ph.D., former Chief of the Fire Science Division of the National Institute of Standards and Technology (NIST), has called for an independent review of NIST’s investigation into the collapses of the World Trade Center Towers on 9/11.

Dr. Quintiere made his plea during his presentation, “Questions on the WTC Investigations” at the 2007 World Fire Safety Conference. “I wish that there would be a peer review of this,” he said, referring to the NIST investigation. “I think all the records that NIST has assembled should be archived. I would really like to see someone else take a look at what they’ve done; both structurally and from a fire point of view.”

“I think the official conclusion that NIST arrived at is questionable,” explained Dr. Quintiere. “Let's look at real alternatives that might have been the cause of the collapse of the World Trade Towers and how that relates to the official cause and what's the significance of one cause versus another.”

Dr. Quintiere, one of the world’s leading fire science researchers and safety engineers, also encouraged his audience of fellow researchers and engineers to scientifically re-examine the WTC collapses. “I hope to convince you to perhaps become 'Conspiracy Theorists', but in a proper way,” he said.

In his hour-long presentation, Dr. Quintiere discussed many elements of NIST’s investigation that he found problematic. He emphasized, “In every investigation I’ve taken part in, the key has been to establish a timeline. And the timeline is established by witness accounts, by information from alarm systems, by any video that you might have of the event, and then by calculations. And you try to put all of this together. And if your calculations are consistent with some of these hard facts, then perhaps you can have some comfort in the results of your calculations. I have not seen a timeline placed in the NIST report.”

Dr. Quintiere also expressed his frustration at NIST’s failure to provide a report on the third skyscraper that collapsed on 9/11, World Trade Center Building 7. “And that building was not hit by anything,” noted Dr. Quintiere. “It’s more important to take a look at that. Maybe there was damage by the debris falling down that played a significant role. But other than that you had fires burning a long time without fire department intervention. And firefighters were in that building. I have yet to see any kind of story about what they saw. What was burning? Were photographs taken? Nothing!”



This person used to lead the Fire Science Division at the NIST. He followed the NIST WTC investigation and his (very critical) comments are included in the 2005 congressional transcripts on the results of the NIST report.


This is what poster SanderO just wrote about an exchange he had with Dr Quintiere:

"I attended a seminar at John Jay College a number of years ago at the Christian Regenhard Center. Quintierre, Ms Regenhard, Prof. Glenn Corbett were among those who attended. The seminar was to examine the response and investigation of NIST. They looked at official responses to large fires in the past, egress issues and so on.

They did not discuss engineering at all. I had the honor to speak with A few of the presenters including Quintierre and Ms Regenhard (She did not present)... and did an over view to Quintierre about ROOSD. He was interested but said he was not an structural engineer and not competent to evaluate its veracity. We corresponded a bit after that."
 
I have no problem admitting that I did not understand a lot of things 4 years ago. So what? I have learned some, and moved on somewhat.

I understood that BZ 2002 had it right - a simple, limiting case, not claiming to describe the actual WTC collapse scenario, just showing that the towers (and indeed any steel frame structure) were doomed once the top block reached a velocity equivalent to having fallen through one story (if you think about this, this holds true even if there isn't a block anymore!). The real world lesson is that you want to keep building from starting to fall.

I never claimed to have read, let alone understood, let alone have agreed with, any of Bazant's following papers. I did discuss the "crush-up-crush-down" thing for a while, and even opened a thread more than two years ago, asking users to clue me in on an amateur level: Bazant in a nutshell. There, I wrote on June 8th, 2012, that I had understood that the "crush-up-crush-down" model "isn't applicable to the WTC". Besides yourself, femr2 and ozeco41, others provided helpful posts: LSSBB, W.D.Clinger, ... oh well, and then the thread fell asleep, and when it was revived a year later, some Truther snatched it with nonsense, and I stopped reading.

That was more than 2 years after this thread was started and I informed all readers of their misinterpretation of BV eqs 12 and 17.

Page 2 of this thread:

CRUSH DOWN FOLLOWED BY CRUSH UP, 2006-2010, R. I. P.

BAZANT AND VERDURE EQUATIONS OF MOTION, EQS 12 AND 17, 2006-2010, R. I. P.


If we accept the ROOSD study as accurate, one logical consequence is that the claims in the papers BV and BL are incorrect.

BV eqs 12 and 17 are the origins of the 'crush down, then crush up' concept.


2 years is a long time but you did learn. In this sense you are smarter and more flexible than the following posters:

Newtons Bit
R Mackey
Dave Rogers and Myriad

NB and Myriad still cannot distinguish between the BZ argument and the crush down and up equations of motion in BV. Please read a collection of their comments linked above.

Can you spot any mistakes in their comments?


You don't think that debating random users, mostly non-experts like myself, on the internet, will get you anywhere?

Not my purpose. Don't underestimate yourselves. This forum is an excellent source for viewing common and popular memes.

I anticipated years ago that historic revisionism is inevitable on this subject. I want to record it in action.


For example, this is a new emerging meme within this environment:


The authoritative source describing the collapse progression mode is NIST, before them FEMA. FEMA told of "pancaking", NIST descibed in little (not much) more detail how floor2column connectors fail when impacted by descending floors from above, i.e. ROOSD. So yes, "this collapse mode is well recognized and well documented within available literature"
.

As I look over the entirety of the written history of the collapses and collapse modes, including JEM publications, media, and comments in and on technical literature, I see no evidence whatsoever that this meme is true.




Why does it bother you that a handful of posters on a rather obscure forum that no practicing engineer would ever go to for advice are - perhaps - wrong?

Are definitely wrong and in sharp denial of their mistakes. This environment is nothing special by itself, but it does serve as a microcosm of the most pervasive memes on the subject of the WTC collapses.

The group may be poor with technical argument, but it is very in tune to the memes which form historic revisionism of the technical history of the collapses. The group has even creatively made up some memes of their own.
 
“I think the official conclusion that NIST arrived at is questionable,” explained Dr. Quintiere. “Let's look at real alternatives that might have been the cause of the collapse of the World Trade Towers and how that relates to the official cause and what's the significance of one cause versus another.”
*snip*
In his hour-long presentation, Dr. Quintiere discussed many elements of NIST’s investigation that he found problematic.

It's rather disingenuous to mine quotes from Dr. Quintiere without any mention of what he found "problematic."

Quintiere said:
The official investigation conducted by the National Institute of Standards and Technology (NIST) concluded that the collapse was due to the fires heating the core columns that were stripped of insulation by the aircraft impacts. An alternative cause is considered that puts the cause on insufficient insulation of the steel truss floor members.

Dr. Quintiere objects the the NIST conclusion that if the fireproofing hadn't been stripped off, then the builidings would likely not have collapsed. He believes they would have, because the building code requirements are inherently inadequate.
 
More to the point, I guess, is this: M_T, do you think that Dr. Quintiere's list of "real alternatives" includes magical silent explosives and imaginary thermite cutting devices?
 
It looks to me that M_T tried hard to find evidence of CD, convinced there had to be, and having found none, bitching about engineers is his consolation prize.
 
With the gift of hindsight, what has been learned about structural vulnerabilities to these systems:

We now know that at any time since 1970 accidental or intentional local detachment of only 2 floor slabs in only one portion of either of the buildings could have led to catastrophic failure of an entire building. This coud have happened even without the loss of a single column.

Um, actually, that was Dr. Eager's initial "zipper" hypothesis in 2001, wasn't it?

Eager said:
The perimeter tube design of the WTC was highly redundant. It survived the loss of several exterior columns due to aircraft impact, but the ensuing fire led to other steel failures. Many structural engineers believe that the weak points—the limiting factors on design allowables—were the angle clips that held the floor joists between the columns on the perimeter wall and the core structure (see Figure 5).

But thanks for the "gift" anyway -- it's the thought that counts.
 
We now know that at any time since 1970 accidental or intentional local detachment of only 2 floor slabs in only one portion of either of the buildings could have led to catastrophic failure of an entire building. This coud have happened even without the loss of a single column.

Now know? This isn't an original idea of yours, Major_Tom. Every single one of the buildings I have ever designed would experience a total and catastrophic collapse if two the floor slabs suddenly detached. This isn't unique to my buildings, either. It's true for just about every single building ever built.
 
Now know? This isn't an original idea of yours, Major_Tom. Every single one of the buildings I have ever designed would experience a total and catastrophic collapse if two the floor slabs suddenly detached. This isn't unique to my buildings, either. It's true for just about every single building ever built.

Mr. Bit...

Perhaps the distinction here is when one refers to a twin tower slab *detaching* from the columns... it seems to refer to a 208'x208' less the core area... In a typical grid frame a detached floor slab might be no more than 25x25 or 30x30 and not impact the other slabs in the grid and perhaps not lead to a total building collapse.

It seems that the collapse in a grid style building would be local and not total even if one bay collapsed to the ground.

No?

So the distinction here I think is the column free space with huge slab areas.
 
Mr. Bit...

Perhaps the distinction here is when one refers to a twin tower slab *detaching* from the columns... it seems to refer to a 208'x208' less the core area... In a typical grid frame a detached floor slab might be no more than 25x25 or 30x30 and not impact the other slabs in the grid and perhaps not lead to a total building collapse.

It seems that the collapse in a grid style building would be local and not total even if one bay collapsed to the ground.

No?

So the distinction here I think is the column free space with huge slab areas.

Wat? It's no easier for a system of 60' long trusses at 3'-4" OC to suddenly detach from the structure than a grid of 30x30 wide flanges at 10'-0" OC. And neither is going to magically do it themselves.

Even in the WTC, the trusses detaching from the columns was a minor part of the collapse. Please see the NIST report for why collapse initiation started. Once started, global progression is a certainty.
 
I asked you before but you didn't answer (sorry if I did miss it). What is your problem with the towers floor system(you have actually misrepresented it)? It was not up to the extraordinary conditions of 9/11 but, why should it have been?

As I observed The Towers to "unpeel like a banana" - i.e. outwards - there was an obvious failure of the floor to column connectors. Once I found out that they were made from 3/8" steel angle welded to the column and two 15/16th bolts holding the truss - I wondered how the hell anyone had allowed construction to be that peared down!

If I have misrepresented anything, I apologise, as I have no direct experience of looking at The Towers - I've only trawled through the available stuff on the InterWeb - and we only have to go as far as these pages to see that not all folk agree with it!

I don't have a general problem with crinkly tin floor pans - they are a neat idea to avoid the forests of shuttering and props on more traditional sites - but I genuinely feel that despite good numbers to prove their worth - ultra thin floors and equally thinned down support structures are not a good development.
 
Wat? It's no easier for a system of 60' long trusses at 3'-4" OC to suddenly detach from the structure than a grid of 30x30 wide flanges at 10'-0" OC. And neither is going to magically do it themselves.

Even in the WTC, the trusses detaching from the columns was a minor part of the collapse. Please see the NIST report for why collapse initiation started. Once started, global progression is a certainty.

That wasn't the point.... I suppose if all the outside the core space is one slab and it collapses it leaves the perimeter columns and the core columns... they may then topple too.

if one bay collapses it leaves all the other slabs intact and most of the frame and it likely will remain standing.....

no?
 
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