Truss Failure Theory Inconsistent; Critically Flawed

Hopefully, this isn't taken as being "off-topic":

Isn't NIST's job to find out as many shortcomings in materials and standards used to construct buildings? They needed to find out which, if any, standards weren't met, and if there were problems with materials used.

I would think it'd be difficult to perform their job when they had very little actual evidence to look at. NIST is probably frustrated as hell, just as many here are, with the lack of evidence available. Their frustration is apparent in reports like:

wtc.nist.gov...

..wherein they state that NO STEEL WAS RECOVERED FROM THE WTC 7 debris.

My questions lie more in why the evidence isn't available than actual mechanisms of failure.

In another thread I stated jokingly that we should ask the Myth Busters to build a tower as to specs and fly an airliner into it. Another member then, not understanding that this was sarcasm, proceeded to let me know how ridiculous that suggestion is. This member then stated "You could never be one 100% sure of colums destroyed, flow of fuel etc,etc..." to recreate the disaster as it happened.

And actually he makes a good point. How could both towers collapse perfectly when they were two different buildings hit in different locations by different airplanes? Seems like there's too much coincidence. Or am I wrong?

To get back on topic, the truss failure theory still doesn't explain why the buildings fell as quickly as they did.

I'm asking the experts here (Vushta and Howard) what the calculations are for the difference between the static and dynamic loads everyone is speculating on? I find it hard to believe that even complete failure of one set of trusses (even on one whole storey) would cause the entire building to collapse (when we take the central core into consideration). Unless the change from static weight to dynamic forces of that weight above would be enough to disintigrate the structural elements below the failure...I'm seriously just asking.

Those trusses worked from the time the first employees moved their personal effects into their offices/cubes until an hour after the impact of the first plane. Fires weakened the steel, buckling caused inward and outward bowing of the outer columns (which as I understand where structural for wind load bearing; whereas the vertical load was supported by the central core), breaking the attachment points of the floor trusses and in an instant, (one hour after the first impact) the first tower turned to dust...is that basically how it happened?

Originally posted by Griff

Originally posted by BigTrain
I do not believe that a failure in load trasfer caused the collapse. I believe it was the soul result of collapsing floor trusses which caused the collapse because as the floor fell, it greatly reduced the lateral stability of MANY columns, and that is why u have a sudden collapse, because of the lateral failure of multiple columns all at once.

I have a question about this. When the trusses were failing, do you believe that they all fell at once or do you believe they fell chaotic? If they fell chaotic, wouldn't they then give lateral support by kinda forming a diagonal type support? That is if one side fell while the other side stayed connected. Just a question.

Or, would taking out the core result in floors sagging/trusses failing/exterior columns being "pulled" in (i.e. buckling)/ and when the load became too strong it collapsed at the weekest part of the building (the impact zones)?

No matter how they fell, the only way they can provide lateral support is in their designed profiles. It is the top flange of the floor that transfers the inward forces to the core. If there is no connection to the core, how can there be load transfer. And once these floors fell, it was game over. If you watch the video, the big puffs of smoke, which only occur once or twice, which shoot out the building like 20-30 floors below the collapse I believe are some of the floor sections pancaking slightly ahead of the exterior collapse.


[edit on 3-8-2006 by BigTrain]

Big Train,

I see what you are saying. I was looking at it as the connections to the core missing but the outer columns intack. But basically, after thinking on this thought more, I have concluded that you're right. The floor trusses wouldn't be butting against the core or exterior anyway, once collapsed, because of the size. Take care.

Originally posted by cryingindian


And actually he makes a good point. How could both towers collapse perfectly when they were two different buildings hit in different locations by different airplanes? Seems like there's too much coincidence. Or am I wrong?

Um, bro, one building tilted, the other fell straight down, and both hurled debris for blocks, how is this anywhere near a perfect collapse?

Train

[edit on 3-8-2006 by BigTrain]

Originally posted by Griff
Big Train,

I see what you are saying. I was looking at it as the connections to the core missing but the outer columns intack. But basically, after thinking on this thought more, I have concluded that you're right. The floor trusses wouldn't be butting against the core or exterior anyway, once collapsed, because of the size. Take care.

NIST report states the truss to perimeter columns were failed in a downward motion. The truss to core columns were not failed in a downward motion.

Originally posted by Valhall
NIST report states the truss to perimeter columns were failed in a downward motion. The truss to core columns were not failed in a downward motion.

Thanks Valhall. So, That actually would go along with my theory of the core being taken down right?

Originally posted by Valhall

Originally posted by Griff
Big Train,

I see what you are saying. I was looking at it as the connections to the core missing but the outer columns intack. But basically, after thinking on this thought more, I have concluded that you're right. The floor trusses wouldn't be butting against the core or exterior anyway, once collapsed, because of the size. Take care.

NIST report states the truss to perimeter columns were failed in a downward motion. The truss to core columns were not failed in a downward motion.

Thats right, the majority of the connection failures would be at the exterior walls. The most important thing here is that, even under normal everyday working conditions, if one floor were to come crashing down onto the next, even without fire and plane impact, the floor being impacted still doesnt have the capacity to resist the upper floor.

Train

Originally posted by Valhall

Originally posted by Vushta


How do you know this if you don't have all the data and the referenced data may not be all the data involved in the conclusion?

Vushta,

Have you read the report? Because this question makes me think you haven't.

Okay, you're the NIST and you've been tasked (and paid) do perform an exhaustive investigation, analysis and modeling of what happened with the towers. And you issue your final report and use your one shot at reviewing the metallurgical evidence on this statement (I'll paraphrase because I'm not going to go find this portion of the report for the 14th time):

Of all the steel we looked at none of it looked like it got over 250 C except for two pieces that we think got to 600 C - and by the way, we think those two pieces got that hot while they were buried in the debris pile - not before collapse. And further more, we don't think any structural element saw elevated temperatures of fire for the whole duration of the fire. FURTHERMORE, they go and self-implicate themselves in their sloppiness by saying - we think we might have picked debris from the debris pile kind of wrong. WTF?

And then you go on to present a theory of failure that is based on "weakened steel due to extreme temperatures over long period of times that induce creep" (and then misuse what the affects of creep are) that you've already admitted IN YOUR ONE SHOT TO TELL THE WORLD THE FACTS, you couldn't find!

This isn't "omitting data".

Valhall..I've read through it. Have I studied it? No. It would do little good for me to study the math involved.

My point of NIST not having all data and methodology explained is leaning more to the methodology side. Its my understanding that NIST purposely selected areas of mid range temps for the data for the FEA simulations. I think this is why in one area it can state 'no steel above 250C..and then claim 'steel at 1000C.'

I need to check this more for validity, but using mid range temps would make sense.
This is what I mean about a possible confusion of data vs. conclusions without knowing the hows and whys of the methodology. Which by the way was not in the scope of the report. The use of standard forensic methodology is implied.

Originally posted by BigTrain

Um, bro, one building tilted, the other fell straight down, and both hurled debris for blocks, how is this anywhere near a perfect collapse?

Train

[edit on 3-8-2006 by BigTrain]

Um, "perfect" not in the way they fell, but "perfect" in the fact that they both collapsed completely. I guess I should have used the word completely.

Big Train, I'll be honest with you...If someone could sell me perfectly on the truss failure theory, which I think would be better to call the BOLT AND WELD FAILURE theory, meaning the 5/8" bolts and the welds which connected the trusses on each end failed, causing the floors to pancake, causing the building to turn to dust; I'd be a lot happier than I am now thinking something besides the plane impacts and fires caused both complete collapses. Believe me when I say I'm trying to find a way to accept the "official" story.

I really think that the vertical load bearing core played more of a role in the collapse than the floor structure failure. Even though the concrete in the core was steel reenforced, don't you think that the planes' impacting the cores at the height they did would maybe break the "femur" (to use an anatomical annalogy) of the building, either at the site of impact or well below it, maybe at a point where concrete pours where separated or some other weak point. That would make more sense to me than the "puncturing of the screen by a pencil" and the failure of one or even two storey's floor systems, causing complete collapse.

I think your statement that one building tilted and the other fell straight down prooves one thing. The "official" story has some "splainin' to do." If there was one mechanism for collapse, they both would have fallen the same way, right?

Originally posted by BigTrain
Let me see if I understand YOUR viewpoint and correct me if im wrong.

It was a wrong interpretation, or at least off topic.

The point is there should not have been an instantaneous failure from a single truss/buckling failure when "critical mass" or whatever you would like to call it had not yet been reached.

There was NO REASON for an instantaneous buckling to have taken place, as HowardRoark claims, short of a new mechanism being described in which truss failures can propogate themselves without the need of insupportable loads from already-failed/buckled columns.

Originally posted by Griff

Originally posted by Valhall
NIST report states the truss to perimeter columns were failed in a downward motion. The truss to core columns were not failed in a downward motion.

Thanks Valhall. So, That actually would go along with my theory of the core being taken down right?

Yeah, I would think this implies downward motion of the core, pulling the floor trusses with it.

Vushta,

I don't think I've "studied it" either. That's why I usually ask "has anybody found..."??? Because I've read several sections of it (like the steel analysis section), but not the whole thing.

You still seem to be missing my point on this. They are required to state such things as "mid-range temperatures are being cited". Actually, I would get reprimanded at my work if I did a full test analysis and did not attach at least a representative population of the data used in my analysis. So, I'm thinking they probably could have had an appendix of empirical data, and I'm also thinking they probably got paid enough, they should have had an appendix of empirical data.

Bad form - that's my point. You don't make contradictory statements to your theory - not if you actually have more data that will back your theory. That's just Engineering 101 gross blunder stuff there.

[edit on 8-3-2006 by Valhall]

Valhall, Let me see if I can dig up some backing to the idea of mid range temps being used. It might take a day...I have to actually do something now...as in try to get something done.lol.

Originally posted by cryingindian

Big Train, I'll be honest with you...If someone could sell me perfectly on the truss failure theory, which I think would be better to call the BOLT AND WELD FAILURE theory, meaning the 5/8" bolts and the welds which connected the trusses on each end failed, causing the floors to pancake, causing the building to turn to dust; I'd be a lot happier than I am now thinking something besides the plane impacts and fires caused both complete collapses. Believe me when I say I'm trying to find a way to accept the "official" story.

Smaller steel elements take much LESS (Edited) energy to heat up and fail compared to columns. The very small in comparison bolts and welds would easily be the first to buckle under the fires. Also the very small cross-section truss elements, unprotected by fireproofing would also go near the same time, any heat rising from the floors heats the above truss elements. It is reasonable to assume these members were exposed to the greatest temperatures since they reside directly above any burning fire.

Train

[edit on 3-8-2006 by BigTrain]

Reports from inside the building jsut prior to the collapse confirm that the floors were already starting to fall prior to the collapse. This is such an old arguement....

Stop looking at the pictures and read the accounts of the people who were there, the transcipts to the PA and NYPD at the WTC site. THere were reports by NYPD helicopters that they could see the building tilting minutes prior to the collapse.

Why is it so hard to realize that a building, that was created for space not rigidity, could collapse after a fully fueled plane crashed into it....

www.zombietime.com...

Look at these phots, look at the debris, and try maybe talking to someone who was there....

The only conspiracy is that people are still trying to find an aswer and blame the government after 4 seperate investigations.

[edit on 3-8-2006 by esdad71]

Originally posted by esdad71


The only conspiracy is that you are still trying to find an aswer and blame the government after 4 seperate investigations.

I'm getting extremely sick and tired of these type comments being inserted in this type discussion. You don't know my intent. Not if you think it's that when I've stated so many times I could puke exactly what it is.

There are also numerous reports by occupants of the building, in NYPD tapes and transcripts, as well as first-responder official reports that there were explosions on lower level floors of WTC 1 and collapses on lower level floors of WTC 1, so I think I'll take your advice and incorporate that evidence into the big picture I'm trying to accumulate.

Thanks!

Originally posted by BigTrain
Smaller steel elements take much energy to heat up and fail compared to columns.

True, but it's also impossible to exceed the temperatures of the fires heating them, and especially when taking into account all other mass that would've acted as a heat sink (everything from the air and smoke, to the concrete and other steel) you're not looking at THAT much heating.

Tests have been conducted that have heated steel to as much as 600 C with "uncontrolled" fire (seems to not go much hotter than this with such a fire), and these tests show that structures will sag, but not fail, including the bolts.

That the bolts would be the first to fail may seem most logical (I'd sooner believe actual parts of the truss itself, personally), but it's a shame that this hasn't been shown to happen in any actual tests with this kind of structure, including NIST's very own. Nor do we know how much heat/what temperatures would be required to cause that kind of failure.

It seems likely to me that if it were possible in the WTC with hydrocarbon fires alone, then it would be possible to recreate the failures outside of them in a controlled experiment.

BigTrain, I'm saying that you can't have truss "failure" causing global collapse without failure at the point of attachment. The trusses could warp and bend out of structural integrity shape all they wanted, but for a floor to collapse, the bolts have to fail. So if the fires weren't hot enough to cause failure of the bolts, then the forces of the warping of the trusses workiing against the bolts must have caused them to shear. See what I mean?

Valhall, not sure why the backlash, but this was not directed at you. It was directed to this as a whole.

I have studied, read, gone over, thought about and even accpeted the notion of "could my country have done this?" I have read FEMA, NIST ,9/11 commission and the Silverstien study, and they are all conclusive and give valid points.

If someone could answer, or give ANY solid proof to the use of demolitions, it would be greatly appreciated. This would totally debunk ANY of the official stories.

My thoughts have always been that the accident exposed the weakness of the actaul buildings, and that due to design, it was very vulnerable in this type of attack. Read the history of the building ot the towers, the codes that were not adhered to, the construction after the WTC bombing in 93. I mean, could you imangine the lawsuits if it came down to the fact it was the poor construction that aided in the collapse. You could also be looking at manslaughter charges for each death, right?

The upper half of the building could not be supported anymore, and they fell. This is so simple it is ridiculous. Do all of you have any idea how large these buildings were? I feel the fact that they were not cut in half that day is a miracle. Those targets were chosen because they were thought to cause the most damage. Jsut as they placed the explosives in the 93 bombing to hopefully topple one building into the other, this time planes were used.

After the attacks, it was a combination of heat and weight that led to the steel weakening and not bieng able ot support the 20 or so floors above it.

Just a suggestion, pick up the book "102 minutes", it is all about the people who were in the building that day, and some theories on things such as missle attacks and explosions are explained by the PA and NYPD workers.







[edit on 3-8-2006 by esdad71]

Originally posted by cryingindian
BigTrain, I'm saying that you can't have truss "failure" causing global collapse without failure at the point of attachment. The trusses could warp and bend out of structural integrity shape all they wanted, but for a floor to collapse, the bolts have to fail. So if the fires weren't hot enough to cause failure of the bolts, then the forces of the warping of the trusses workiing against the bolts must have caused them to shear. See what I mean?

And what if the bolts didnt fail, but the piece of steel they are connected to, What if the L-bracket experienced plate shear, or pullout. What if the steel got hot enough to cause the bolts to just "rip" through the plate. There are much more mechanisms of failure than just bolt shear alone.

And bsbray, did these "tests" also include heavily loaded, deformated and smashed floor trusses that occured after a plane smashed through them, didnt think so.

Ya know bsbray, I didnt discount your theory from day one, I actually tried to follow some of the things you have brought up and looked into, but my experience in this field and my lack of finding anything at all that would suggest demolition, I have to again say, I just dont find one shred of proof that the method of collapse was not what is publically stated by the reports.

Train

BigTrain,

There's no way to know what failed where and in what mode, or what was the weakest point of any given bolted/welded connection was unless we have the data. And we don't. And we most likely never will. But it should have been available through the investigation we (I'm talking about U.S. taxpayers) paid for.