could that at least be partly due to the fact that this was not a discussion between experts but a general presentation to a broadly diversified audience?
i will post a link later where dr jones debunk the nist miths. it's a much more detalied analysys then the video presentation; u gotta understand that he didnt have enough time to thoroughly discuss everything at lenght in the conference. and the 10second collapse was attributed to wtc7 not the towers.
the likelyhood that all three buildings collapsed on their own weight due to fire alone is pretty much laughable: chances are slim and none with slim just leaving the scene. i think we can all agree upon that.
No. Not at all. These buildings were unique in design. They're not easily comparable to other steel frame buildings. The weight was borne in the towers both by the core and by the perimeter tube columns: neither group was sufficient on its own to support the buildings. They were about 95% empty space. If either core or exterior or about half of all the columns on one floor failed, that floor would give way. That much was known when they were built, I think. Not necessarily. It would depend on the adequacy of the insulation of the support members in buildings, and again the nature of loading and temperatures that occurred in those fires. That's not at all clear. In those other buildings the frame presumably remained well enough insulated. There were no airliner crashes in those buildings, apart from the one into the Empire State building, and that was a much smaller, slower plane in a building with a lot of exterior masonry which the towers lacked. It's widely suggested that the fuel burned probably no more than 15-20 minutes. But the fires clearly remained burning for at least 1hr and thus could have kept the steel at high temperature for some time, although not perhaps as high as 550 C. But 550 C could have been reached initially. That inital jolt might just start the failure process. I've suggested that the timescale to failure is not easy to predict, but is a very complicated question, one that depends on the precise way in which the steel deforms under stress and temperature, and precisely how and when the steel was heated. Yes. The office materials provided, certainly, a lot more but lower temperature flame. I think it depends on what you mean by weaker here. It seemed pretty clear to me from about one or two days after I had seen the collapse, that a possible failure mechanism was simply that one story near the level where the planes hit had failed completely, and that the parts of the buildings above then fell through one story, impacting onto the parts below. I and some of my friends made a ballpark calculation of what would happen in this case, within a day or two of 9/11. It's not too hard to estimate what the dynamic stress would be produced on the lower part of the building if that ever happened, and it's very easy to see that it is far in excess of what the building was designed to take. It was designed to be strong enough to support its static weight and a bit more, and that's all. So the structure it seems to me could have been about as strong as it was expected (was designed) to be, and still have failed, if something like half of the supporting beams were cut on any one floor. So it was weak enough to fail in this manner. Now I frankly don't know whether this was understood before 9/11. But I think there are no steel frame buildings that possibly could survive an event in which a sufficiently large part of the top of the building fell onto the bottom. In addition, the towers were, I believe, designed to last for long enough in an ordinary fire that they could be evacuated. Any treatment of fire depended on the assumption, of course, that the insulation on the beams would remain intact in a fire, and that there would be no major structural damage pre-existing at the time of the fire. It is not at all clear that anything other than impact damage was considered in the case where an airliner struck one of the towers, and there is no existing documentation of what the assumptions were in this study or of what actuall damage the impact would have done. So the conditions of no more than minor structural damage and intact fire insulation, as it seems to me, could well have been violated in the collapse of towers 1 and 2, due to the impact damage caused over several stories, combined with the fires. But both 1 and 2 were struck by airliners and had fires, right? So these two occurrences are not so unlikely, if you can believe the general collapse scenario. And while building 7 was not struck by an airliner, it evidently did had extensive fires, and it evidently was struck by falling debris from building 1. There is quite a bit of visible damage in the photos, and there is considerable testimony from the firefighters that suggests the damage was much more extensive than what is already visible. Thus I suspect that a similar basic failure mechanism was operating there ... only it must have been one of the lower floors that suffered sufficient structural and fire damage to give way. So it doesn't seem all that unlikely to me. Cheers! And thanks for your response.