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What really happened ....11 september
- Thread starter NickBarings
- Start date
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.
sure? wasn't it 6.5 or something for WTC7?Quote from Bitstream:
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.
Quote from man:
but doesn't that somehow mean that you would expect more
buildings having come down due to fire in history?
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.
your argument would indicate that within the chaotic situation of major fire
such spot point deformation would happen all the time, no?
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.
i mean in each and
every burning steel frame building you would expect some hot burning parts in
direct contact with the frame, thus resulting in the effect you described.
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.
and
as i understand it the fuel burned too quickly to do all this.
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.
simply because
either it falls apart almost immediately or, if later, the "hot spots" can
hardly be the result of th already burned fuel.
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.
and if it was not the fuel
then it must be other "normal" stuff, which you should find in more or less
each burning building, no?
Yes. The office materials provided, certainly, a lot more but lower
temperature flame.
as i understand it the basic argument is that the structure of
the towers was significantly weaker than expected.
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.
actually of
all three buildings. and while this can well be, i find it amazing.
as i understand NIST tries to point out that several things added
up to make the weaker-than-expected structure fail. but it seems
relatively unlikely that these several things add up a second time
the same day and some other things add up in some other way
for a third building.
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.