I need all debunkers I can get!

Architect said:
I'm thinking of taking it for a living. Erm, just a minute, I do. Ah well. :)

This is my current favourite of his:



To state the obvious, there is a dearth of detail as to how the loads transmitted, design capacity of the appropriate members to accept such altered load paths, and thereafter whether the members subsequently carrying the increased vertical load had sufficient capacity.

I mean, it's pretty basic stuff I would expect any competent construction professional to twig.
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I'm not sure he's considered the idea that the spandrels might fail. Ah well.
 
Moving swiftly along, we have this stundie-worthy gem:
Note that less than 10% of the mass is steel in the supporting columns and that as much as 70% is concrete. If this mass filled the total volume of the building above the initiation zone (190 000 m3), the uniform density would be 0.18 ton/m3 or the density of cotton! You could say that a big bale of cotton (mass above) rested on the structure below!
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Setting the accuracy of the figures to one side for the time being, I have to laugh at the premise here. A tonne of feathers, or cotton (wool), or any other such substance weights a tonne. Density is of little practical relevance to the substance of the discussion other than in an attempt to divert attention away from the key issues.

Here's another factual error, but this time one which he wouldn't have made had he actually aquainted himself with the NIST report:

Manual calculations were done and to be on the safe side you added steel and built strong! And steel was quite cheap at that time. And US steel was good quality. The assumed yield stress 248 MPa was probably much higher in reality. NIST never checked the yield stress of the steel in the rubble!
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NIST did, of course, test steel samples. As I recall the reason wasn't just to test strength against design capacity, but also because foreign steel had been substituted with different standards. Everything turned out fine, but if I were making a CT case I would at least get my facts right. I'd also learn the difference between England and the UK (pet peeve of mine):
English authorities
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Architect said:
With respect, you appear to either misunderstand or willfully misconstrue the point put to you.

You have stated that steel structures are not, in themselves, susceptible to failure during normal fire loading conditions. I have provided you with a series of links which show that this is not, in fact, a tennable position. There is a wealth of fire test data which corroborates heat induced failure at normal fire loadings, and this is reflected in building regulations across the globe.

I therefore put it to you that one of the cornerstones of your argument is a blatant falsehood, and suggest that you either clarify your point or acknowledge your apparent error.
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And my position is quite clear - low stressed steel structures subject to heat <500° C, e.g. 200+ vertical columns under compression, does not 'suddenly collapse' simultaneously. Evidently an individual steel column is affected by heat as outlined/linked to in my article and should not lead to sudden collapse of it; in this case we discuss an assembly of 200+ columns spread over 4000 m², where the total effect is even less likely.

Thanks for your interest in my article. I might clarify accordingly.
 
Architect said:
NIST did, of course, test steel samples. As I recall the reason wasn't just to test strength against design capacity, but also because foreign steel had been substituted with different standards. Everything turned out fine, but if I were making a CT case I would at least get my facts right. I'd also learn the difference between England and the UK (pet peeve of mine):
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The steel strength is actually higher than the design strength. This is because if a contractor tests a piece of steel on his job and finds it deficient, he has a legal method for suing the mill and having the mill pay to replace every piece of steel on that job and/or do extensive testing.

Mills aren't crazy, they usually gave themselves about a 5% buffer though.

And steel wasn't cheap in the 70's, it was expensive (comparitively). Today, labor controls the cost of most projects while the materials don't. We frequently use extra (alot extra) on jobs to reduce the labor involved in construction.
 
Architect said:
Whilst acknowlegiu are simplifying for ease of reference, you make a number of basic errors here. In particular it is important to understand that WTC1 and 2 essentially comprised a composite structure of 4 main elements;

1. - The external envelope, which provided resistance against wind loads and also carried half the weight of the floors.

2. - The internal core, which (amongst other things) provided resistance to the overturning moment and carried the remaining weight of the floors.

3. - The trussed floor girders, which indeed helped restrain the outer facade.

4. - The roof level girder trusses, which acted to transfer loads betwixt core and envelope.

The important thing here is to understand that the building is dependant upon the integrity of each of these in order to ensure stability, hence the loss of one (beyond certain margins) can - and did - lead to progressive failure.
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Not at all.

1. is obvious and clearly described. The wall carry 60% of the static load and are low stressed, 22.5% yield, to allow for lateral wind loads.

2. the core carries 40% of the static load and are higher stressed, 30% yield. No overturning moment need be considered in this simplified analysis (evidently the outer core columns are stronger than the inner ones, etc).

3. The static vertical loads on the floors are generally carried to the adjacent columns. It is agreed that the floors can transmit some horizontal loads (wind) from one wall to the core and to the opposite wall, etc. The floors cannot transmit any big vertical loads in a core column to a wall column as shear (the bolts will shear off and there are no real webs in the floor trusses).

4. The hat trusses are assumed just to transmit the load on the roof - the mast - to all columns. The hat trusses are similar to the floor trusses but slightly stronger. In my simplified analysis they do not play any role.

Happy?
 
Heiwa said:
And my position is quite clear - low stressed steel structures subject to heat <500° C, e.g. 200+ vertical columns under compression, does not 'suddenly collapse' simultaneously. Evidently an individual steel column is affected by heat as outlined/linked to in my article and should not lead to sudden collapse of it; in this case we discuss an assembly of 200+ columns spread over 4000 m², where the total effect is even less likely.
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1. No, you stated that steel structures were not susceptible to fire-induced failure under normal conditions. You subsequently added a vague comment about global collapse. Now you've started adding more caveats. Is there some sort of problem in stating your case cogently?

2. Your latter part is based on an assumption that progressive collapse requires complete simultaneous failure of all structural elements, presumably on the basis that load transfer will work around isolated failures. Is that a fair summary?
 
Architect said:
Here's another example of where you get it wrong:



What you mean is that the floors are a composite structure comprising up to 4 inches of reinforced concrete sitting attop permanent steel shuttering, in turn supported by the trussed girders. What you wholly fail to appreciate, presumably because ships don't tend to have such floors, is that the steel shuttering itself acts as reinforcement and hence the pattern of failure will be rather different.

For example excessive load would lead to additional stress on the steel, which is strong in tension, and failure of the concrete (which is strong in compression) will not be the first sympton of failure.

I mean really, do you know anything about building construction?
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The WTC floor design is clear to me. Evidently we do not build ship decks like that but in galleys, etc. we use a steel deck (plate/beams) + concrete, etc. We do not use shore floor truss designs either, but I understand the principles. We never bolt a concrete floor to a deck on a ship. All is welded (and stronger). But at university the basic structural analysis was same for house architects and shipbuilders.

So I know a little. Thanks for your interest.
 
I notice that you're continuing to avoid answering the highlighted technical errors in your report. Just like you did to Newton.
 
Heiwa:
How do you explain the floor sag and columns bending inward seen on the videos and by the police helicopter pilots?
 
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Architect said:
Moving swiftly along, we have this stundie-worthy gem:


Setting the accuracy of the figures to one side for the time being, I have to laugh at the premise here. A tonne of feathers, or cotton (wool), or any other such substance weights a tonne. Density is of little practical relevance to the substance of the discussion other than in an attempt to divert attention away from the key issues.

Here's another factual error, but this time one which he wouldn't have made had he actually aquainted himself with the NIST report:



NIST did, of course, test steel samples. As I recall the reason wasn't just to test strength against design capacity, but also because foreign steel had been substituted with different standards. Everything turned out fine, but if I were making a CT case I would at least get my facts right. I'd also learn the difference between England and the UK (pet peeve of mine):
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The key issue is evidently the mass above - and that it volume wise is 95% air. I like the cotton allegory! Nist makes it appear as a solid block of concrete coming falling down.

I have not found any Nist samples of the steel of the WTC1 floors 94-98 steel structure so I assumed the yield stress and steel origin (US). The UK steel was much worse as I recall (British ships built in the 60's often just fell apart due bad steel!!! )
 
Heiwa said:
So I know a little.
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Yes, you do know a little, and you're making a fool of yourself before people who know a lot.

I think you're smart enough to understand the principles involved, Heiwa, but you have a strange compulsion to try to make reality fit your beliefs. That will never happen as long as you believe in nonsense.
 
Heiwa said:
So I know a little.
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That much is very apparent. The problem is that you believe "knowing a little" is enough. And not just enough, you seem to believe that "knowing a little" somehow puts you far ahead of those who know a lot, from specific education and experience.

Where do you get off with such arrogance?
 
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Architect said:
1. No, you stated that steel structures were not susceptible to fire-induced failure under normal conditions. You subsequently added a vague comment about global collapse. Now you've started adding more caveats. Is there some sort of problem in stating your case cogently?

2. Your latter part is based on an assumption that progressive collapse requires complete simultaneous failure of all structural elements, presumably on the basis that load transfer will work around isolated failures. Is that a fair summary?
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1. Normally steel structures do not collapse due to heat. Everything else burns leaving a steel skeleton!

2. Local collapse of any steel part of WTC1 is not expected in WTC1 given the circumstances. If for any reason, e.g. bad steel/workmanship/quality, a single part (a column?) would locally collapse releasing energy, the redundancy ensures that no progressive collapse would occur, i.e. the energy released is absorbed by the intact adjacent structure. The local collapse is then arrested.
 
Gravy said:
I think you mean wealth of detail.
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Not at all. I meant that our Scandanavian friend's article and arguments exhibited a dearth of detail.

Thought Hogmanay had arrived a little early in Scotland, did you? :)
 
DGM said:
Heiwa:
How do you explain the floor sag and columns bending inward seen on the videos and by the police helicopter pilots?
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The floors are of course difficult to see inside the walls. The floors in way of the hole in the wall are not sagging at any time. On one unclear video it is suggested you can see that a floor bolted to a wall has dropped down, i.e. the bolts must have sheared off, but I doubt that. Bad quality of the video?

Wall perimeter columns bending inward? Based on the available loads/stresses/cross areas/slenderess ratios and boundary conditions it is unlikely that it would occur. It is recommended to check the videos and photos again.
 
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