9/11 Structural Engineer's poll 19

[WARose]

A former colleague of mine who is a structural engineer (now retired and with apparently too much time on his hands ) discusses various conspiracy theories on the net. One of them is the 9/11 theory that holds that the buildings that fell on that day did so due to a controlled demolition. (A theory he feels is “nonsense”.)

You've probably heard followers of this theory called “Truthers” (or worse). In any case, aside from telling my friend that he is/was apparently a member of the CIA (and trying to say he wasn't even a structural engineer), apparently another angle of argument is to say that the profession is somehow afraid to talk about it (noting a lack of support in journals, etc) or that my friend somehow doesn't know what the profession talks about. That got me wondering how much this is discussed beyond my (and his) experience. So the question I have as sort of a poll for structural engineers:

Is the controlled demo theory something that is a regular topic of conversation with your colleagues?

AND (if the answer to the above question is “yes”) Do you feel compelled to view it one way or the other?

Speaking for myself, I cannot think of a single time it has come up (except in conversations with my retired friend mentioned earlier). I've certainly discussed the failures on that day with other structural engineers as an example of progressive collapse. But not much beyond that.

However, public awareness on the topic (I would call it misinformation) seems to have done nothing but grow over the years......and will likely grow more in the years to come.....so I thought I'd ask fellow structural engineers for their thoughts and ideas as to be better equipped to answer the public’s concerns in the future.

 

[Trenno]

So Building 7 fell due to an office fire. I read somewhere, a critical transfer element failed and thus lead to the progressive collapse.

Anybody able to elaborate?

There's been a recent push in the Aus standards (Link) for Structural Robustness - certainly gives a good argument to minimise transfers when debating with the Architect!

 

[WARose]

[blue](Trenno)[/blue]
So Building 7 fell due to an office fire. I read somewhere, a critical transfer element failed and thus lead to the progressive collapse.

Anybody able to elaborate?

Basically (as I have said elsewhere in this thread), WTC 7 was a bit odd in terms of it had a number of cantilevers (and other systems) to redistribute the vertical load. The building's layout (in plan view) overshot it's foundation (which was placed years prior the building being built). The result was that a lot of vertical load had to be redistributed from some of the upper floors down to the foundation. (A pic:

https://en.wikipedia.org/wiki/WTC_7#/media/File:Wtc7_transfer_trusses.png)

Perhaps this made the building more susceptible to the fire that brought it down.

As far as the actual "trigger" goes (i..e. what initiated the collapse).....the frequently mentioned culprit is a girder that was forced off its seat by thermal expansion of some beams that framed into it. This loss of bracing caused "Column 79" to buckle......and down the rest came.

I've read some "Truther" arguments that say the girder could not have been physically forced off its seat by the thermal expansion involved. While that may be true.....I ran some calculations that show very little movement was required to over stress the seat with the day to day gravity loads it would see.

 

[ornerynorsk]

7 has always been a bit of an enigma to me, but it helps to hear a more technical explanation (not a structural guy). I've witnessed chain-of-event situations in mechanical failures, albeit on a much, much smaller scale and complexity, that defy imagination at first glance, and then make perfect sense once the root cause analysis is performed.

What doesn't help is Larry Silverstein going on national TV and saying "that we decided to pull it". I read somewhere that he came out smelling like a rose on 7, to the tune of $500 Million to the good, after insurance settlements.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[IRstuff]

Interesting video from thread815-419858 shows collapse of an admittedly much shorter building after a fire.

TTFN (ta ta for now)
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[waross]

I saw a purported video of the collapse of building seven. A friend who is a retired demolition contractor said that it showed a textbook case of controlled demolition. The penthouse subsides first and then the entire building starts to drop as a unit.
The problem is, the video was taken from some distance away and I have never been assured that it is in fact a video of building seven and not some other building.
Would someone use a video of a different building to make a point on the internet?
As for Larry Silverstein; Could he have meant evacuate it?
At some point it would make good sense to acknowledge that the fires could not be extinguished and "Pull" out first responders.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ornerynorsk]

Verbatim - "I remember getting a call from the fire department commander, telling me that they were not sure they were gonna be able to contain the fire, and I said, 'We've had such terrible loss of life, maybe the smartest thing to do is pull it.' And they made that decision to pull and then we watched the building collapse." –Larry Silverstein

It could be taken either way, but it's a very curious way to state "we decided to get everyone out". When he says "pull IT", IT is a very strange way to refer to people. Sounds like he's talking about an object, like maybe a building.

And then there is the underlying detail that buildings are not simply "pulled" on a moments notice. Weeks of preparation = planning and foreknowledge. Mind-boggling implication.

My opinion, the jury is still out on the whole damned day. I may be callous, but for all of the good that there actually is in the world, mankind is capable of terrible, unthinkable, incomprehensible evil. For most of us, to think of something other than the accepted narrative, to ponder what the alternative really entails, simply overloads cognitive reasoning. I'm not 100% convinced one way or the other. I'm a naturally suspicious person, and too many things don't add up, but the "evidence" that most of the nut-job conspirists put out for public consumption doesn't hold a lot of water, either. One thing I am convinced of, is that if there is another side to this, it will never see the light of day.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[btrueblood]

Or maybe he meant to say "pull out" and just mis-speaked.

 

[ornerynorsk]

BTW - nobody was in 7 at that time. It had already been evacuated, so the "loss of life" comment is also unclear. 7 had no casualties that day.

Food for thought ~

Craig Bartmer, a former officer of the NYPD [1]:
"I walked around it (Building 7). I saw a hole. I didn't see a hole bad enough to knock a building down, though," said Bartmer. "Yeah there was definitely fire in the building, but I didn't hear any I didn't hear any creaking, or I didn't hear any indication that it was going to come down. And all of a sudden the radios exploded and everyone started screaming 'get away, get away, get away from it!' It was at that moment ...I looked up, and it was nothing I would ever imagine seeing in my life. The thing started pealing in on itself ...Somebody grabbed my shoulder and I started running, and the shit's hitting the ground behind me, and the whole time you're hearing "boom, boom, boom, boom, boom." I think I know an explosion when I hear it ...Yeah it had some damage to it, but nothing like what they're saying ...Nothing to account for what we saw I am shocked at the story we've heard about it to be quite honest."

In his book dealing exclusively with the mystery of WTC 7 collapse, David Ray Griffin has devoted an entire chapter to disregarding of the testimonial evidence by NIST. He quotes a journalist, Peter Demarco of the New York Daily News [2]:
There was a rumble. The building's top row of windows popped out. Then all the windows of the 39th floor popped out. Then the thirty eighth floor. Pop! Pop! Pop! was all you heard until the building sunk into a rising cloud of gray.

-----
While the 9/11 Commission ignored WTC 7 altogether in its report, NIST (National Institute of Safety Technology) did file several reports on their studies of the collapse of WTC 7. While NIST went to lengths in its tortuous analyses to state that it found no evidence of a demolition job in WTC 7, it was not honest in its study because it entirely ignored testimony of witnesses from both the inside and outside of WTC 7. With regard to the Twin Towers both the NIST as well as the 9/11 Commission had ignored witness testimony because eye witnesses to the event, numerous survivors from within the buildings, as well as those who watched things from very close quarters, stated unambiguously and consistently that bombs kept going off in all buildings.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[IRstuff]

Explosions are NOT indicative of bombs, per se. If you were to torch your house, you'd probably hear quite a few explosions, unrelated to the actual bombs in your basement. Cans of solvents, cleaners, etc. make fairly large bangs when they get cooked.

TTFN (ta ta for now)
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[ornerynorsk]

Agree with you IRstuff, there are other things that could have produced popping noises. However, even if there were a lot of spray cans, etc lying about in the buildings, would that have the force and energy to blow out windows of the type used in commercial highrises? Doubtful. A couple cans of air freshener or furniture polish just wouldn't do it. And there would be no reason for all of these aerosol containers to begin spontaneously bursting on floors of the building which had no fire. I remember a television interview of several fire dept personnel that day or shortly after that mentioned "bombs going off all over the place". They had been on the lower floors of 1 or 2 just prior to collapse, I don't remember which.

As a kid I used to have great fun throwing aerosol cans into the burn barrel and waiting for the ensuing explosion. Although they were better than black cats and cherry bombs, they were still pretty tame. The sound certainly would not carry through multiple floors of a finished building, nor would the concussion of what little shockwave they generate. Small quantities of solvents, household chemicals, etc are all relatively low energy. They just don't have the speed and energy content to propagate the kind of shockwave that commands your attention.

It's a very interesting subject. I love discussing it, but the first reaction of most people is anger when it is suggested that anything other than the official government narrative could have a spark of merit.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[IRstuff]

Are these people saying that the explosives were planted just prior to the collisions? That alone is challenging, since a typical demo is done with the building stripped, so that the specific members that need to be blown are readily accessible.

Are these people also saying that somehow, the rather imprecise process of crashing a jet into a building resulted in exact correlation with the a priori placed explosives? Or are they saying the explosives were placed on every single floor and that someone, somehow, was able to set up the specific explosives corresponding to the actual crash locations of the planes?

Or are they saying the explosives were planted when the buildings were built, in anticipation of this event 28 years after the construction? I kind of like this last scenario; it shows how deep the government conspiracy extends ;-)

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[SwinnyGG]

I've always believed strongly that the 'explosions' people refer to are the rapid failure of brittle elements of the structure such as windows, parts of the facade, and perhaps of the structural elements themselves.

In response to the veracity of eye witness testimony, I have three responses:

1) The average American has never heard anything actually explode, outside of a Michael Bay film. When a building is coming down, there's going to be a lot of things failing in a lot of different ways, generating a LOT of noise. There's lots of very large, very heavy things crashing into other large, heavy things with a lot of impact energy. That can be very loud, and can do things like make the floor of a building vibrate in a very unfamiliar way. Without understanding what is happening around them, what is the average person going to call an event which is extremely loud- maybe the loudest sound they have ever and will ever hear- combined with a building moving around them in ways they never thought possible? What vocabulary do they have to describe this event? 'Explosion' is one of the few terms that everyone knows.

2) The average American has what I describe as net-negative understanding of engineering (incorrect conclusions based on inaccurate assumptions because some complex engineering topics appear simple to the uninitiated), meaning that they have no idea how fragile something like a building can be when the right forces or stimuli are applied. They assume that buildings and bridges are monoliths that are impervious to damage and will last forever no matter what they are subjected to. We, as trained engineers, obviously know this is not the case. They don't understand things like the simply massive amount of energy contained in a fully loaded jet traveling at 500 mph, or that very large steel structures are often only strong when loaded the way they were designed to be loaded.

3) Ask any cop, or accident investigator, or anyone else who deals with witness testimony on a daily basis and they will all tell you the same thing: witness testimony is unreliable as often as not. People see things that aren't there, recall events in the wrong order, see faces they think they recognize, on and on.. not because they mean ill or are unintelligent, but because the human mind is not a perfect receptor and processor of information, and it often 'modifies' memories to make things fit within the person's understanding of the world. This is a fact, based on years of psychological study. If you don't believe it, there is ample reading about it. Add a massive adrenaline hit to the mix (which, biologically, does things like make lights brighter as pupils dilate and sounds louder as the brain goes into full fight or flight) and people's recollections of simple events can very quickly become unreliable.

 

[WARose]

Look and (especially) listen to any controlled demo and then compare it to the collapses on 9/11. You'll see and hear the differences pretty quick.

By the way, sorry to say a 17 story building collapsed today in Tehran (from fire):

https://www.youtube.com/watch?v=sPGr4D1-zDI

Condolences to the families of the firefighters who died.

 

[MacGruber22]

My opinion, the jury is still out on the whole damned day. I may be callous, but for all of the good that there actually is in the world, mankind is capable of terrible, unthinkable, incomprehensible evil. For most of us, to think of something other than the accepted narrative, to ponder what the alternative really entails, simply overloads cognitive reasoning. I'm not 100% convinced one way or the other. I'm a naturally suspicious person, and too many things don't add up, but the "evidence" that most of the nut-job conspirists put out for public consumption doesn't hold a lot of water, either. One thing I am convinced of, is that if there is another side to this, it will never see the light of day.

This is an unbelievable paragraph. You go from broad speculation that suggests demolition to complaining about conspiracy theorists and their "evidence". Your comment regarding an evil world fits squarely into "evidence".

You give off the vibe that you get your second medical opinions from your plumber.






"It is imperative Cunth doesn't get his hands on those codes."

 

[ornerynorsk]

IRstuff, I don't think anyone is disputing that it wouldn't be a challenge. Challenging, yes, impossible, no. In addition, 7 was never hit by a plane. Pre-planted 28 years in advance? Not sure I've ever heard that one, but let's just say highly unlikely :>). Yes, I know . . . . sarcasm.

Good points, everyone. As I said before, I am not 100% convinced one way or the other, though I do steer toward the official version. After all, 100's of people would be privy to the operation were it an actual conspiracy. I really don't see that many people being able to keep a secret of that scope and magnitude, even under the threat of death. Is that kind of evil possible in our own government? You better believe it.

Anyway, once we fear to play the devil's advocate, if even for the sake of casual discussion instead of actual discovery, we all become yes-men. Bought and paid for. The danger lies in summarily dismissing ideas which venture outside of what we consider to be normal, particularly where there are some unmitigated outliers that muddy the lens and absolute proof is not necessarily possible. But, it's really not normal to intentionally fly airplanes into buildings then, is it?

So, how many of you take the Warren Report at face value??? Haha. Really, let's not go there.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[ornerynorsk]

MacGruber22, I'm not sure what is so unbelievable about not being convinced 100% one way or the other. Kudos to you if your mind is made up. I like to think from more than one angle. I was not aware that this thread was exclusive to the "Yep, that's exactly the way it happened" club.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[WARose]

[blue](ornerynorsk)[/blue]
I was not aware that this thread was exclusive to the "Yep, that's exactly the way it happened" club.

It isn't. I (for one) welcome alternative p.o.v.(s).

I especially would like to hear the commentary of a impact guru (on some of the things I have said and his/her comments in general).

 

[ornerynorsk]

Thanks WARose. I love hearing both sides, as well. It really does deserve to be discussed from all angles, if for no other reason than to respectfully exhaust all possibilities for the memories of the 2996, all those who have died from related causes, all those who have yet to die as a result of exposure to dust and debris, and all of those who had their loved ones mercilessly ripped from their lives. That miniscule shred of uncertainty demands at least some attention.

If I were a betting man, I would bet that there are plenty of folks on Eng-Tips who share at least some doubt, as well, but aren't comfortable being on the "wrong" side of the discussion. That's OK, though, for some us that is our comfort zone. If it causes someone to question and think, to open a door and peer into those otherwise verboten places, whether or not they participate, that's what separates us from the animals.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[WARose]

[blue](ornerynorsk)[/blue]
If I were a betting man, I would bet that there are plenty of folks on Eng-Tips who share at least some doubt, as well, but aren't comfortable being on the "wrong" side of the discussion.

In any failure, there is going to be some doubt/questions. In this case especially because we are talking a situation [with regards to WTC 1&2] involving two very complicated processes: impact and dynamic buckling. Even most structural engineers don't deal with those topics on a day to day basis.

 

[MacGruber22]

ornerynorask - you are more than welcome to have any opinion you want here or anywhere else. That doesn't mean you get to be sheltered from strong criticism of your generalizations and reliance on allusion/doubt as evidence.

It really does deserve to be discussed from all angles, if for no other reason than to respectfully exhaust all possibilities for the memories of the 2996, all those who have died from related causes, all those who have yet to die as a result of exposure to dust and debris, and all of those who had their loved ones mercilessly ripped from their lives.

That is called a red herring argument. Now, there is obviously a place for pathos in many argumentative situations. However, it is not substitute for evidence and analytical rigor that is required to evaluate the mechanics of such a complicated building collapse. In your search for an alternate cause to the collapse, you may find better footing by sticking to challenging the specific investigative engineering findings in the previous reports.

"It is imperative Cunth doesn't get his hands on those codes."