Did Bush watch plane hit the first tower ?

[defaultdotxbe]

NIST did take samples from the columns in the debris and none (or maybe 95%) showed any indication that the steel had been at temps above 600 F.

did you happen to read how they determined that? they analyzed the paint on the columns

they stated that many of the columns couldnt be analyzed because they didnt have enough paint on them

does it stand to reason that perhaps at temperature much higher than 600F the paint completely burned off? (and therefore couldnt be analyzed)

The structure is built at every floor to hold the weight above and then some. All we have with collapsing floors is some additional acceleration

i think you severely underestimate the effects of this additional velocity

 

[uk_dave]

Second NIST did not say that the sagging in the floor trusses caused the external columns to bend, it said that it caused the interior core columns to bend. And Finally you claim that global collapse is a given in the statement that structural collapse is a given. Really? Please quote some pre 9-11 literature where this is stated. The structure is built at every floor to hold the weight above and then some. All we have with collapsing floors is some additional acceleration and lateral displacement, so why is it a given that a floor that was built to hold the weight above it suddenly has no chance. Plus if it such an easy calculation why not do it.

ahhhhhh now I understand your problem.

OK, well actually NIST did state that the failure of the columns was due to the sagging of the floor trusses which depended on both the inner and outer columns for support. Photographic evidence shows the inward bowing of the outer columns and no doubt debris evidence also points to distortion of columns leading to failure.

But you really really don't understand the concept of floors. You claim that the floors were designed to support the structure above!! Lightweight steel trusses supporting corrugated steel pans decked with 3-4" of lightly reinforced concrete plus the dead and live loads of a normal office was all the floor structures were designed to take.

The floors were severely and immediately overloaded by the collapse of the structure above the impact zone.

And since these floor assemblies also restrained the inner and outer 'tube' of columns then their failure lead directly to the failure of the columns.

As we have all said time and time and time again

 

[Non Believer]

As usual neither of you have provided any specific evidence, or even a common sense response to my questions. Default you put to unrerlated quotes together and apparently consider it causation. does the nist report say temps over 600F cause all paint to be burned away. No. Do they say that temps over 600F will not be able to be analyzed because all the paint burns away. No, and so to answer your question no it dosen't stand to reason. and it is nice that you think I underestimate the acceleration, but prove it.
As for U.KD congratulatiuons this seems to be one of your first attempts at a discussion rather than your usual innuendos. Well if I don't understand floor design you certainly have done nothing to change that. You seem to point to my statement the the structure below is designed to support the structure above as the clue to my ignorance. This seems as much as a common sense statement as I can imagine, unless your point is that all structures transfer weight to the ground that they are standing on. Skilling and others have made statements that the towers were built to withstand additional loads other than the normal dead and live loads. These buildings were clearly built with extra capacity.

Lightweight steel trusses supporting corrugated steel pans decked with 3-4" of lightly reinforced concrete plus the dead and live loads of a normal office was all the floor structures were designed to take.

So your claim is that they were maxed out and could not take any more load? This is just clearly wrong according to statements by the engineers. Of course statements by experts have little place as evidence by all of you.By the way what is your source for the structural information on the towers, and where can the public go to get specific information? I am sure you are all for the public having information right?

 

[uk_dave]

As for U.KD congratulatiuons this seems to be one of your first attempts at a discussion rather than your usual innuendos. Well if I don't understand floor design you certainly have done nothing to change that.

You mean you don't understand the concept that a framed structure functions as a whole and each element of that structure is interdependent on other elements?

You don't understand that the floor assemblies are only designed to support their own dead load and the live load inposed upon them by normal office activities?

You don't understand that the columns transfered the vertical loads down to the foundations but required the internal floor assemblies to resist the lateral loads of wind?

You don't understand that unrestrained columns carrying a vertical load will tend to move and once this movement occurs they will fracture and break apart?

Well, i tried.

 

[Woody-]

So your claim is that they were maxed out and could not take any more load? This is just clearly wrong according to statements by the engineers. Of course statements by experts have little place as evidence by all of you.By the way what is your source for the structural information on the towers, and where can the public go to get specific information? I am sure you are all for the public having information right?

I'll try to paint a clearer picture. The columns in the core and walls supported the weight of all of the structure above them, each floor truss only had to support the weight of the people and contents of one story plus a safety factor. When the tower collapsed the columns of the top section no longer lined up with the columns of the remaining structure so a good portion of the falling mass was hitting the floor trusses which were not designed to handle anywhere near the load of the whole structure above them.

Here is what Mark Loizeaux, the president of Controlled Demolition Incorporated had to say about the collapse in an interview shortly after the attacks.

http://www.newyorker.com/fact/content/articles/011119fa_FACT?011119fa_FACT

So what's going to happen? Floor A is going to fall onto floor B, which falls onto floor C; the unsupported columns will buckle; and the weight of everything above the crash site falls onto what remains below—bringing loads of two thousand pounds per square foot, plus the force of the impact, onto floors designed to bear one hundred pounds per square foot. It has to fall.

Bolding mine.

 

[defaultdotxbe]

Default you put to unrerlated quotes together and apparently consider it causation. does the nist report say temps over 600F cause all paint to be burned away. No. Do they say that temps over 600F will not be able to be analyzed because all the paint burns away. No, and so to answer your question no it dosen't stand to reason. and it is nice that you think I underestimate the acceleration, but prove it.

they also said the temperatures they were able to determine are not necessarily representative of all the columns in the impact area

or does that part not count because it doesnt agree with your forgone conclusions?

 

[Architect]

OMFG. You really are just ignoring everything that doesn't agree with you, aren't you. Well, on the off chance that you aren't just a 28th/PDoh/Se7ven/RB sock puppet lets try and pick up some (more) of your points.

Well if I don't understand floor design you certainly have done nothing to change that.

The whole structure (floors, core, outer facade) act together as one structure. The best analogy I can give you is if you think of it all as a big space frame of girder. The floors represent the intermediate struts, transferring loads from facade structure to core and so on.

Skilling and others have made statements that the towers were built to withstand additional loads other than the normal dead and live loads. These buildings were clearly built with extra capacity.

Yes. And that capacity is what allowed the building to stand up following the loss of structural elements in the initial explosions. However it is still a finite capacity.

In any event the Edinburgh University study and the Arup paper (you should be familiar with these, if you're serious about this) suggest that fire along could have caused failure (this contradicts the NIST paper).

Lightweight steel trusses supporting corrugated steel pans decked with 3-4" of lightly reinforced concrete plus the dead and live loads of a normal office was all the floor structures were designed to take.

A 100mm reinfoced slab is still pretty substantial, and in any event it had a permanent steel formwork which would act to provide further reinforcement. But what's your point?

So your claim is that they were maxed out and could not take any more load? This is just clearly wrong according to statements by the engineers.

Have you read the report? Trusses sag due to heat, trusses pull external facade structure inwards, structure fails (as would be expected), collapse is initiated.

Really mate, you're not arguing your case very well here. Whatever that case is....

 

[Non Believer]

You know if you guys are so intent that I have no understanding pull out a quote that shows it. Your main point seems to be that I don't understand that the building functions as a whole, where have I said anything to contradict such a mindblowingly basic premise as that. It seems to be a basic strategy with you guys to claim that I just don't understand, but unfortunately for you, you can't point to what that something is.

It appears UKD misunderstood my statement about the floors below the impacts ability to support the floors above as literally meaning the floor spans. This is not the case. The reference is to the remaining structure below the floor levels of the impact. Perhaps I should have referred to the stories below the impact zone. So to answer all your questions. Yes I understand all your basic points about the construction of the building, so perhaps now we can get on with the discussion

Is it your opinion that because I believe their should be at least a rough calculation for the effect of the upper structure upon the lower during a collapse means that I don't understand the building functions as a whole? Skilling's example clearly demonstrates that he could calculate for a weakened lower floors ability to support floors above, so what's the problem? Are you guys going to insist that there is no calculation available?

Quote from Woody-
bringing loads of two thousand pounds per square foot, plus the force of the impact, onto floors designed to bear one hundred pounds per square foot. It has to fall. bringing loads of two thousand pounds per square foot, plus the force of the impact, onto floors designed to bear one hundred pounds per square foot. It has to fall.

Where do you get these numbers Woody?

Also your claim on lateral displacement seems to be your own theory (in terms of a large amount of the collapsing material hitting the floor trusses). Unless you can quote it in NIST.

As for Architect TFA- you tell me I don't have a good argument, I don't think you even understand my argument. So here is the main argument - Remaining building structures below areas of damage still have their structural integrity intact, and offer resistance to the collapsing portion above. It seems likely that this resistance to collapse is measurable. We can estimate the weight of the top 20 or so floors, and measure their likely acceleration. So where are those numbers?

You claimed that asserting a building that has suffered a partial initial collapse of a floor would automatically lead to global collapse. As in your quote-

Progressive collapse under the imposed loadings is exactly what we would expect. Are you claiming that the lower structure should have resisted the loadings? I should warn you that this would be quite at odds with normal structural expectations.

I should warn you that is exactly what happened in one of the major high rise fires in Spain. a portion of the building collapsed, but the floors below held. Why does it make any sense that buildings that were built to withstand huge live loads (estimated to be 2000 times in the perimeter columns) would have no chance to withstand the collapse of the portion of the building above? I asked before to show evidence of your quote above, and you haven't. Instead you just repeat obvious understandings about the construction of the building, and then claim I am somehow ignorant of all this. Get it together mate.


Default- I did not say it was not possible that some of the steel may have reached temps above 600F. I said that the existing evidence did not support that theory.

 

[Gravy]

Skilling's example clearly demonstrates that he could calculate for a weakened lower floors ability to support floors above, so what's the problem?

The problem is that the floors below don't have to support a floor or two above, they have to support the entire top of the building that's falling. No can do.

I should warn you that is exactly what happened in one of the major high rise fires in Spain. a portion of the building collapsed, but the floors below held.

I should warn you that you have no idea what you're talking about. The concrete core of the Windsor building did not collapse. The outer steel columns in the fire affected areas did, causing the floors to hinge downward. Some floor plates remained attached to the core. The entire top of the building did not come crashing down on the bottom. The building did not suffer structural damage caused by an airliner strike.

​

 

[Non Believer]

So what you have said to contradict me Gravy. I didn't say a floor or two, I said twenty. The buildings were built to support these floors initially (or did you forget that). Yes there is going to be additionally force with collapse, but the structure was built to withstand additional force.
As for your Windsor example, what is that supposed to prove? it looks like several of the floors collapsed, but then stopped. So it actually helps my point, that initial collaspse does not lead automatically to global collapse. So I am going to repeat if you guys want to claim that I don't know what I am talking about, please refer to the exact quote I have made and how it is mistaken.

 

[uk_dave]

It appears UKD misunderstood my statement about the floors below the impacts ability to support the floors above as literally meaning the floor spans. This is not the case. The reference is to the remaining structure below the floor levels of the impact. Perhaps I should have referred to the stories below the impact zone. So to answer all your questions. Yes I understand all your basic points about the construction of the building, so perhaps now we can get on with the discussion

OK so you understand that the structure dealing with transfer of the vertical loads to the foundations has to be capable of handling that load and presumeably at some point you will mention redundancy so we'll get that one out of the way now.

The redundancy of the design is based upon a best guess as to the amount of damage a building could suffer in a reasonably predictable event and results in over design of the structure to compensate for this possible damage scenario. However if the damage exceeds this design allowance then the building will be stressed beyond it's capacity and catastrophic failure will occur.

Now, you also claim to understand that a frame building works as a whole, but even with this understanding you appear to still require clarification as to why the lower structure was unable to support the structure above the damage zone.

Well in simple terms the impact damage suffered by the structure took it very close to the limit of it's redundancy. However, it did remain standing. The subsequent fires and their effect of this highly stressed structure was the tipping point which caused catastrophic failure.

The lower structure (below the impact zone) would be able to support the load as obviously no additional mass is being added to the building, though the momentum of falling material would make that mass impose a much greater load on the structure than if it had been static.

But you have to take into account that the steel inner and outer column structure was dependant on the internal floors for restraint. This is the point you seem to fail to grasp.

By collapsing the top of the tower down through the structure below the imapct zone we are taking out the floor assemblies which are most definately not designed to support the mass of the floors above them. As each storey fails the outward forces of this mass of collapsing material is forcing out the external columns causing the phenomena witnessed on the day.

The columns are now unable to support themselves let alone the rapidly falling mass of collapsing material which is increasing in velocity with every storey which fails and is tearing the columns apart as the floors pull the external columns inward and the falling material pushes them outward.

So, unless you accept that without internal floors those towers would never had stood, you will never understand how they collapsed.

 

[Woody-]

Quote from Woody-
bringing loads of two thousand pounds per square foot, plus the force of the impact, onto floors designed to bear one hundred pounds per square foot. It has to fall. bringing loads of two thousand pounds per square foot, plus the force of the impact, onto floors designed to bear one hundred pounds per square foot. It has to fall.

Where do you get these numbers Woody?

I left the link when I posted it.

http://www.newyorker.com/fact/content/articles/011119fa_FACT?011119fa_FACT

It is what Mark Loizeaux, the president of Controlled Demolition Incorporated had to say.

Also your claim on lateral displacement seems to be your own theory (in terms of a large amount of the collapsing material hitting the floor trusses).

It is a theory based on common sense, it would be virtually impossible for the upper sections to fall straight down so that the load bearing columns lined up with each other. With the tilt of the upper section even if some of the columns would line up others would not.

Unless you can quote it in NIST.

Since the NIST never modeled the collapse that would be impossible.

As for Architect TFA- you tell me I don't have a good argument, I don't think you even understand my argument. So here is the main argument - Remaining building structures below areas of damage still have their structural integrity intact

No, they remaining structures integrity was not intact, the hat trusses in the top few floors were now missing.

http://911research.wtc7.net/wtc/arch/hattruss.html

The hat truss structure strengthened the core structure, unified the core and perimeter structures, and helped to support the large antenna mounted atop the North Tower. The hat truss, which contained both horizontal and sloping I-beams, connected core columns to each other, and connected the core to the perimeter walls. Most the beams connected core columns to each other, while a set of sixteen horizontal and sloping beams spanned the distance the core and perimeter walls. Eight of these, the outrigger trusses, connected the corners of the core to the perimeter walls, while another eight connected the centers of the core's periphery to the perimeter walls.

Without this "hat" the exterior columns and the core columns were no longer "unified".

I should warn you that is exactly what happened in one of the major high rise fires in Spain. a portion of the building collapsed, but the floors below held.

That would be the Windsor Tower. It had a concrete core and two heavily reinforced concrete technical floors, a couple of feature the WTC towers lacked. Funny thing is the collapse stopped at one of the technical floors.

 

[defaultdotxbe]

So what you have said to contradict me Gravy. I didn't say a floor or two, I said twenty. The buildings were built to support these floors initially (or did you forget that). Yes there is going to be additionally force with collapse, but the structure was built to withstand additional force.
As for your Windsor example, what is that supposed to prove? it looks like several of the floors collapsed, but then stopped. So it actually helps my point, that initial collaspse does not lead automatically to global collapse. So I am going to repeat if you guys want to claim that I don't know what I am talking about, please refer to the exact quote I have made and how it is mistaken.

you miss the point that the building were 2 entirely different constructions

the 17th floor (the one that held) and every floor below it were concrete supprted, while the floors above were steel framed around the concrete core, the steel collapsed, the concrete held

but i think the most important difference is the weight ratio, how much did the collapsing section of the windsor tower weigh? and how much did the collapsing section of the WTC weigh?

 

[Non Believer]

To Woody- I went to your link. there is a lot of info there. Could you please just tell me where that quote comes from ?
To UK Dave- so what you are saying is that as long as you get some (or maybe one) of the floor trusses to collapse that will bring down the whole building because that that floor truss will fall on the one below (which cannot support it) and thus lead to global collapse. Makes it sound like it would be pretty damn easy to bring these puppies down then. Why do demolition teams go to such efforts to bring them down when just dropping a couple of floor trusses should do the trick.

 

[Non Believer]

Another quick point.So what is the estimate of additional weight of making floor trusses collapse. And of course we must keep in mind that these floor trusses cannot just snap free of the interior and exterior columns, but must pull these columns down with them.

 

[uk_dave]

Makes it sound like it would be pretty damn easy to bring these puppies down then. Why do demolition teams go to such efforts to bring them down when just dropping a couple of floor trusses should do the trick.

Because controlled demolition tends to try to avoid the chaotic type of collapse witnessed at the WTC and which results in a hugely expensive and time consuming clean up operation.

 

[defaultdotxbe]

Why do demolition teams go to such efforts to bring them down when just dropping a couple of floor trusses should do the trick.

you may have heard of the "controlled" part of controlled demolition? if a CD firm brought down a building in the way the WTC was brought down theyd have their licenses revoked

 

[Non Believer]

Please explain the exact difference between a controlled demolition and what happened to the towers other than securing the area ?

 

[Horatius]

And of course we must keep in mind that these floor trusses cannot just snap free of the interior and exterior columns, but must pull these columns down with them.

Why can't they just snap free? Once they've snapped free, the columns no longer have the same lateral support, so any mass landing on or around them will tend to deflect them laterally, and then gravity will pull them down.

False assumptions are not the way to convince us.

 

[Horatius]

Please explain the exact difference between a controlled demolition and what happened to the towers other than securing the area ?

You did see WTC7 collapse, right?


I admit, it's a tiny difference, but there you go.....