Jazzz said:
I am trying to stick to the single issue which I thought was under discussion - whether the core (undamaged) would stay up by itself.
1. In fact, Jazz, as your other posts here show, it's quite clear that you're trying to claim that the core would have supported the building following failure of floors and hence we should conclude there was foul play.
2. Under such circumstances you
must also address issues such the damage to the core, likely additional damage due to collapse sequence of surrounding fabric, and so on.
3. The structure of the towers (and in fact all such tall buildings) is a complex, closely interlinked system. Trying to focus on one element whilst ignoring the effects on that element of other key factors is a clear indicator that you don't actually understand mechanics or building structures in any sort of competent way.
So that's why I haven't gone on about core damage. However if I was, I could point out that in the NIST model, the extraordinary assumption was made that if a core column had ANY damage it was considered to have totally failed.
4. I'm going to have to ask for your source on that Jazz, because I don't believe it to be accurate.
5. If we look at the full NIST report, they identify a number of different structural models ranging from low to high overall damage. Within each of these models they classify columns as being lightly, moderately, heavily damaged, or completely severed.
6. It is quite clear that moderate damage and above will have affected the loadbearing capacity of that member, whether by weakening the steel or (much more likely) affecting the adjacent joints and hence increasing susceptibility to shear load.
7. However it's clear that believe I misrepresent your views, so why don't you tell US how you believe the damage to toe core should have been calculated in the structural models and where exactly NIST got it wrong? Remember to include all the details.
Another assumption was that there was absolutely no heat conducted down the columns!
8. And what proportion of the heat should have been conducted away by the steel structure? Remember to quote real sources, with calculations and so on.
NIST don't even bother explaining the collapse itself - it just models the WTC up to the point of failure - which of course it can make all the assumptions about the fire temperature/column damage it needs to do. So - we don't actually have a theory of how the building collapsed at all.
9. You seem to be get confused again. We actually dealt with this before. and the paper which you quoted at us indicates that the transfered load would exceed capacity by a factor of around 64. Or do you not agree with that paper anymore.
10. In any event Frank Greening has dealt with this at length, alebit using a simplified model, and although I've mentioned it a number of times previously you've never actually come forward with any comments on his work.
it's really very obvious that a core comprising of 47 columns made of incredibly thick steel (10cm at the base) with deep foundations into bedrock and interlatticed - able to hold millions of tons is going to go pretty much as high as you damn well like.
11. Where are your calculations?
12. YOU say that each tower actually weighed only 500,000 tonnes, and we've proven that the core did not carry all of this, together with which you have failed to justify your 600% figure. Simply shouting "millions of tons" isn't going to cut it as an argument.
I note you poke fun at my factor of redundancy,
13. In the real world, asking for a source for an important piece of evidence isn't considered to be poking fun. Am I to take it from this that you don't in fact have any substantial source or detailed calculations?
I note also that while happy to go on about the floors, you ignored the point about the hat truss being able to hold up the outer shell via the core.
14. What evidence do you have that the hat truss is sufficiently robust to accept a transfered cantilever load in the order of (say) 200,000-250,000 tonnes?
I emailed both Mr. Eagar and Tim Wilkinson on the question of whether the central core would stand up for itself. Interestingly, neither has responded, which surprises me as all here consider it a simple proposition.
15. That you think the structural issues surrounding the collapse are simple merely confirms your own very limited understanding of engineering and mechanics.
