The NIST report, start to finish

reply to post by Azp420


Again I don't really follow you. I ask you to demonstrate that a truss with all members intact can not generate a significant pull in force when heated. You answer that you can't because every structural engineer already knows this, and then ask me to demonstrate why it would be possible. It is the direct result of the truss being in catenary action. Or do you deny that this is possible at all? If not, show why you claim the force as result of the catenary is negligible. I don't really see why I should be the one showing this as I rely on the work from others. I don't have the software they use, nor do I have their models, so I can not repeat the results. It is up to you to show it is impossible, or at least show how you come to this conclusion other than your intuition. Else its just a baseless assertion. As for the fireproofing, look at that paper (ok you reject it but still). The trusses with fireproofing doesn't suffer much at all.

Originally posted by -PLB-
reply to post by Azp420

 

Again I don't really follow you. I ask you to demonstrate that a truss with all members intact can not generate a significant pull in force when heated. You answer that you can't because every structural engineer already knows this, and then ask me to demonstrate why it would be possible. It is the direct result of the truss being in catenary action. Or do you deny that this is possible at all? If not, show why you claim the force as result of the catenary is negligible. I don't really see why I should be the one showing this as I rely on the work from others. I don't have the software they use, nor do I have their models, so I can not repeat the results. It is up to you to show it is impossible, or at least show how you come to this conclusion other than your intuition. Else its just a baseless assertion. As for the fireproofing, look at that paper (ok you reject it but still). The trusses with fireproofing doesn't suffer much at all.

Why don't you demonstrate that it CAN generate a significant pull in LESS THAN TWO HOURS?

The only way to truly do what you suggest is make the trusses and leave off all fire proofing and test them in furnaces for two hours.

So why hasn't the NIST done that? Why should anyone BELIEVE the trusses could generate the pull force until it is PROVEN.

Is this a matter of people BELIEVING what they want until proven otherwise? Do we need to BELIEVE that skyscrapers must hold themselves up? Don't we all KNOW that? So why haven't we been told the tons of steel and tons of concrete that were on every level?

Forget the trusses. Suppose levels 91 through 95 of the north tower could be magically removed. So 15 stories would fall 60 feet in two seconds and impact at 44 mph. Could 15 stories completely destroy 90 STORIES?

Because if not this entire 9/11 business has been TEN YEARS OF NONSENSE. Where has any engineering school simulated that? Talking about trusses is just another useless endless distraction.

psik

reply to post by psikeyhackr


Why don't YOU demonstrate that it CAN'T?

See, we can go on all day here, Psikey.

Originally posted by Varemia

The majority of the time, the reasoning that is done by the people mentioned is based on faulty ideas and misconceptions due to the scale of the towers and how nobody has ever seen anything like 9/11 happen before.

Since this thread has now become Sheffield From Start to Finish*, that's the only reason I'm still in this thread:

"What then happened after the inward bowing is there was a stage at which a critical amount of inward bowing took place, and the columns snapped. And essentially the columns, once they snapped, the inwardly-bowed columns suddenly sprung back and out."
www.pbs.org...

I'm trying to figure out if this is a faulty idea on Shyam's part. Or a misconception. Or a lie. Or disinformation. Or is it actually NIST's position.


And while I'm away I'm also trying to figure out if this is Shyam's faulty idea, misconception, lie or disinformation.

"The measurements have indicated that Tower One collapsed in about 11 seconds, and Tower Two collapsed in about 9 seconds. And the argument goes that this is essentially the rate at which free fall would happen."
www.pbs.org...

Can you help me out? Do you know why he would say such things?




* I'm not knocking the discussion between Azp420 and PLB, but from where I sit I think both agree it's a poorly written paper. Even the person who introduced it into the thread as supporting evidence of something now says the discussion is a little pointless without contacting the authors for more info and that he has no particular loyalty to it. So why did he introduce it in the first place? Where's his validation and support for the paper? Why doesn't he contact the authors to support his supporting evidence?

Point being: Don't we have this information and calculations about the truss pull-in from NIST that you can be debating?

Originally posted by psikeyhackr
Why don't you demonstrate that it CAN generate a significant pull in LESS THAN TWO HOURS?

Because other people which are much better educated in this area than I am have already done that.

The only way to truly do what you suggest is make the trusses and leave off all fire proofing and test them in furnaces for two hours.

If that is the case, why does about every truther claim it is not possible? How do they know this?

So why hasn't the NIST done that? Why should anyone BELIEVE the trusses could generate the pull force until it is PROVEN.

Because it is consistent with the science. I agree that it would have been great if they actually reproduced the whole mechanism and made actual measurements of the pull in forces or even column displacement. Reasons I can think of why they did not is that it is hard to reproduce a similar situation as there are several unknowns, and there is a limited budget and time available. The NIST report wasn't created to satisfy ever wish of you or me.

Is this a matter of people BELIEVING what they want until proven otherwise? Do we need to BELIEVE that skyscrapers must hold themselves up? Don't we all KNOW that? So why haven't we been told the tons of steel and tons of concrete that were on every level?

We believe many things without actually physically observing it. We believe the orbit of pluto is 248 years, yet we only know of its existence for about 80 years. We never actually seen it make a full revolve around the sun. We believe it because the science adds up. That is the reason why I ask Azp420 to show why the science does not add up. Without showing that it is a baseless assertion.

Originally posted by NIcon
"What then happened after the inward bowing is there was a stage at which a critical amount of inward bowing took place, and the columns snapped. And essentially the columns, once they snapped, the inwardly-bowed columns suddenly sprung back and out."
www.pbs.org...

I'm trying to figure out if this is a faulty idea on Shyam's part. Or a misconception. Or a lie. Or disinformation. Or is it actually NIST's position.

Can you explain why you think that is inconsistent with the NIST report? I must agree it is an odd sentence, because it says that after the inward bowing there was a critical amount of inward bowing. The word "after" should be "during" and everything is fine. Is that the problem you have with this quote or is it something else?

reply to post by -PLB-


Did I say it's inconsistent? I just can't find anywhere in the NIST report about this "critical amount". All I see is 55 and 62 inches, nothing about a critical amount. Nor do I see anything about this "snapping." Nor do I see any analysis of these two points.

So is it all right to change the words someone says and then everything is fine and dandy? (Hint: If you read the transcripts you'll find he says it more than once, so it's not just a case of him misspeaking.)

Originally posted by NIcon
Did I say it's inconsistent? I just can't find anywhere in the NIST report about this "critical amount". All I see if 55 and 62 inches, nothing about a critical amount. Nor do I see anything about this "snapping." Nor do I see any analysis of these two points.

The column displacement is investigated, including the moment of failure. I don't see what is so interesting about the snapping. What exactly is there to analyze and why is it relevant?

reply to post by -PLB-

What do you mean by "displacement is investigated"? Did they determine how much a column could bow inward before failure? Was it 55 inches? 62 inches? 74 inches? 84 inches?

What do you mean by "including the moment of failure"? What type of failure did they come up with?

Originally posted by -PLB-
Because it is consistent with the science. I agree that it would have been great if they actually reproduced the whole mechanism and made actual measurements of the pull in forces or even column displacement. Reasons I can think of why they did not is that it is hard to reproduce a similar situation as there are several unknowns, and there is a limited budget and time available. The NIST report wasn't created to satisfy ever wish of you or me.

How do you know it is consistent with the science if it has not been tested?

They tested 4 floor sections for 2 hours and they did not come close to collapse. But they were not bare of fire proofing. So if they try it without fireproofing and it still does not fail then their entire case blows up in their faces. It sounds like they need to not do the test and TALK, TALK, TALK, TALK.

So people can BELIEVE.

We believe many things without actually physically observing it.

It is a semantic flaw in the English language in that we do not have two different words for KNOW where in one case we mean that we KNOW through personal experience versus KNOW due to a second hand source that we regard as reliable. But BELIEVE means something else. Plenty of people BELIEVE there is a God but what evidence do any of them have? There are plenty of blurry photographs of Pluto. Where is there a blurry photograph of God?

Physics is not about BELIEVING!!!

It can be TESTED!

www.youtube.com...

Where is a physical model that can completely collapse?

psik

Originally posted by psikeyhackr
How do you know it is consistent with the science if it has not been tested?

They tested 4 floor sections for 2 hours and they did not come close to collapse. But they were not bare of fire proofing. So if they try it without fireproofing and it still does not fail then their entire case blows up in their faces. It sounds like they need to not do the test and TALK, TALK, TALK, TALK.

So people can BELIEVE.

It is consistent with science because first of all there is no science that refutes it. Secondly there is plenty of science that supports it. A number of studies have been done that come to the same conclusion. Sure it is not 100% absolute certain but science never is.

It is a semantic flaw in the English language in that we do not have two different words for KNOW where in one case we mean that we KNOW through personal experience versus KNOW due to a second hand source that we regard as reliable. But BELIEVE means something else. Plenty of people BELIEVE there is a God but what evidence do any of them have? There are plenty of blurry photographs of Pluto. Where is there a blurry photograph of God?

Physics is not about BELIEVING!!!

It can be TESTED!

www.youtube.com...

Where is a physical model that can completely collapse?

I disagree with your definition of believe. I think what you are talking about is faith. I believe something when there is a sufficient amount of evidence supporting it and none refuting it. That is also how science works. Science is not about absolute truth or absolute knowledge. Of course, the math that is involved with physics is about (absolute) proof. But the models itself never are. Just look at how Newtons laws were proved to be flawed by Einstein. And to some degree it is also a matter personal opinion. Some people will accept a certain theory more easy than others. That doesn't automatically mean one person is stupid or gullible, or the other is stubborn or close minded. Although bias is probably inevitable and does play a role with every person.

For your information, there is a scale model that models a single floor. But I don't have access to it so have not read it. If you are interested, it is called "Scale Modeling of the 96th Floor of World Trade Center Tower 1".

reply to post by NIcon


Its not that simple, many factors play a role, so you wont find the sort of answer you are looking for. If you are interested in this, take a look at NISTNCSTAR1-6 and NISTNCSTAR1-6C.

Originally posted by exponent
You need to have some evidence to start dismissing their results, not just i dont like it.

I have pointed out the evidence, the lack of debris in the footprints, the lack of slowing of the collapse wave, the NOVA video, that's about all the evidence needed to show how the towers ignored the laws of motion. I explained this already, you have a reading comprehension problem it seems. No wonder you buy into all the BS.

No, I already said that is rubbish and almost certainly a graphic image.

What do you mean certainly a graphic image? How does that make it rubbish? Are you saying the pic is rubbish, or NOVA's graphic display of the NIST report is rubbish?

Do you think the columns snapped like that, or not, and if you don't then what do you think did happen? Because as far as I can tell that is NIST's hypothesis, you either support it or you question it. Instead of trying to fill holes with nonsense in order to continue believing in nonsense, an intellectually honest person would ask questions.
That is what I am trying to get you to do with my posts, I hope to spark something in that brain matter that makes you go hmmmm and actually question the OS with an open mind.

I see, so you're playing the typical truther 'my high school education and limited reasoning about the collapse means my physics theories are unassailable!'

High school? I have far more than high school experience in physics and mechanical engineering.

Instead of keep making these claims why don't you actually refute my physics with what you think is correct?
That's the difference between me and you, I explain my physics and you can easily verify my claims, but you don't want to even consider that I might be right.

I explain why I disagree with what you present and get accused of presenting nothing. Everything I say can be verified. You just need to understand and except known physics laws pertaining to collapses, colliding objects etc. Well known fields of physic that do not change with a buildings design.

You don't know what you are talking about. That much is clear given that all plane impact studies of the towers show core column damage from the plane, something you say is impossible.

No study can show planes damaged the columns. They just made assumptions because without their assumptions their hypotheses would be even more nonsense. Studies, unless they have irrefutable evidence, are not proof of anything. They're nothing but appeals to authority, and if you don't have the experience to understand if what they claim is possible or not then you shouldn't be here supporting them. That is nothing but faith. You must be a religious person? Religious people do things on faith, scientific people look at evidence ,and facts, and what is already known.

Many trusses did fail, for a number of different reasons, but it was the failure of the outer wall that initiated the collapse, not the failure of trusses.

Oh I see, the story is changing now. It wasn't sagging trusses pulling in the columns that initiated the failure of those outer columns? Exponent has a new hypothesis!

Where in the NIST report does it show where a number of trusses failed for different reasons?

What caused the failure of the core then?

No, because I have done more than use my own personal incredulity and the soothing text of conspiracy websites. The only reason you believe their hypothesis contradicts itself is that you do not know what their hypothesis is.

I think I know it better than you do mate. You have done nothing but cry and whine about the OS, you have not presented anything but personal opinion based on a bunch of assumptions.

If trusses failed from planes impacts, and according to you OSers the columns became unstable from not having the trusses to hold them, then why didn't the truss failure scenario happen sooner?

Sagging trusses can not put a pulling force on columns, any extra force that might act on the trusses from any centenary action would just cause the trusses to sag more. If you can picture that in your head, and still see the trusses pulling in columns, then your experience in this field must be zero. That is just a logical conclusion mate.
You can argue all you want, but real physics trumps your fantasy world.

reply to post by -PLB-

Thanks for the reference, but I've read them quite a few times so could you be more specific? I didn't see any analysis of the critical moment for the columns and what happened at that moment. I certainly don't see what Shyam stated.

I also don't see how it's so complicated. From NCSTAR 1-6:

"The exterior wall instability was induced by a combination of thermal weakening of the columns, inward pull forces from sagging floors, and to a much lesser degree, additional axial loads redistributed from the core."

That doesn't sound like a lot of factors to me.

reply to post by psikeyhackr

How do you know it is consistent with the science if it has not been tested?

Do you really think they need to test known reactions? We know what happens to steel when it is heated, believe it or not its been done before and the reactions are known.

reply to post by -PLB-

I ask you to demonstrate that a truss with all members intact can not generate a significant pull in force when heated.

Originally posted by Azp420
No matter what the deflection, if none of the members have failed, the truss is unable to generate pull-in force under this loading configuration.

The top chord cannot be in tension without transferring it to the bottom chord and putting that in compression.

Since load is applied at the top of the truss forces are transferred via the diagonals to the bottom chord. A top chord in tension would put the bottom chord in compression. This means the top chord would also have to carry any load in bending which is not being carried by catenary action. I've shown it does not have the capacity to do this.

It is the direct result of the truss being in catenary action. Or do you deny that this is possible at all?

As I mentioned in my previous post, this is an unheard of phenomenon and I was unaware of it until this thread. I'm open to being proven wrong, but I've yet to see how it would be possible in this case. All my calculations and visualizations thus far indicate that it is not possible, although the possibility exists that I may be missing something.

I don't have the software they use, nor do I have their models, so I can not repeat the results. It is up to you to show it is impossible, or at least show how you come to this conclusion other than your intuition. Else its just a baseless assertion.

I can't quickly just whip up these kinds of models either, but I can determine if they are plausible based on their published results. I showed mathematically how I came to my conclusion.

As for the fireproofing, look at that paper (ok you reject it but still). The trusses with fireproofing doesn't suffer much at all.

Originally posted by Azp420
Most fire proofing is not designed to offer much protection after about two hours anyway, and I'm sure there have been many fires around trusses lasting longer than that, or fires where trusses weren't fire proofed.

The protected simulations only ran for 60 minutes.

Originally posted by Varemia
reply to post by psikeyhackr

 

Why don't YOU demonstrate that it CAN'T?

See, we can go on all day here, Psikey.

But you can't demonstrate anything. I demonstrated that a self supporting structure stops a small percentage of its mass trying to crush its own support. It is called experimentation. Does that have anything to do with SCIENCE?

www.youtube.com...

So where is your demonstration?

psik

Originally posted by hooper
reply to post by psikeyhackr

 

How do you know it is consistent with the science if it has not been tested?

Do you really think they need to test known reactions? We know what happens to steel when it is heated, believe it or not its been done before and the reactions are known.

But isn't the amount of TIME required to heat the steel affected by the QUANTITY OF STEEL?

So why doesn't everyone want to know the amount of steel on every level of the towers?

Oh yeah, that would not be SCIENTIFIC!

Whatever happened to the south tower has to accounted for in a ONE HOUR time frame. But there had to be enough steel on the 81st level to hold another 29 stories.

psik

Originally posted by psikeyhackr

Originally posted by Varemia
reply to post by psikeyhackr

 

Why don't YOU demonstrate that it CAN'T?

See, we can go on all day here, Psikey.

But you can't demonstrate anything. I demonstrated that a self supporting structure stops a small percentage of its mass trying to crush its own support. It is called experimentation. Does that have anything to do with SCIENCE?

www.youtube.com...

So where is your demonstration?

psik

How many effing times does this have to be disproven? Your model has NOTHING to do with the collapse dynamics of the towers. They didn't crush down like that AT ALL. It's called a BAD EXPERIMENT.

reply to post by NIcon


Take a look at 1-6C chapter 6. They analyze 5 different situations and determine if instability occurs.