@Plum
"No.
I'm saying that damaging or even completely removing single digit
percentages of columns, from a tall building, that is not a tower or
aerial, will not cause a complete collapse of the building. And even
then, it will fall along a curve since there is less resistance along
that route than the resistance offered by the structurally sound parts
of the building."
Well the experts that compiled the NIST report are saying otherwise, due to the events of that day and the design characteristics of 7 WTC it can and did happen.
"A) There
are two parts of debris you have to discount when looking at the final
picture you posted. 1. Debris from North Tower, this is the debris in
the bottom of your picture. The same debris which damaged WTC7 and is
strewn across WTC6. Then 2, slide-off debris, which came off of the top
of the 5 story pile of rubble that WTC7 ended up as when it settled.
Once
you remove those two, and see that hardly any debris even made it
across the streets on each side of WTC7...keeping in mind this was a
fifty story high building...It fell into its footprint."
It did not fall into its own footprint. While some of the debris directly south of 7 WTC are from the towers, its not true to say hardly any debris made it across the streets either side of 7 WTC.
The Verizon building to the left of 7 WTC sustained $1.4 billion dollars worth of damage, and that mostly came from the collapse of 7 WTC. You can see in the photos debris from 7 WTC completely fill the street between the two building a larger amount of debris resting against the Verizon building.
Debris resting against Verizon building in the top of picture.
Damage to Verizon building from 7 WTC debris.
That's just the Verizon building.
Fiterman hall to the north of 7 WTC was so badly damaged from 7 WTC collapsed it had to be demolished.
"B) Yes, I've read the NIST report. I take it that you are referring
to the consequences of thermal expansion? Before anything else, I'll
merely ask the following...do you think that architects, engineers fire
safety regulations are unaware of vertical thermal expansion?
Imagine
a "L-shaped" bit of steel. One length being vertical and the other
length being horizontal. Now, apply heat to the corner. Guess which of
the vertical or horizontal lengths will carry the heat further. You know
the answer already...the vertical part.
So, fire on one floor of a
building will heat a column on that floor, and that expansion will have
an effect on the column length in floors above and below the burning
floor. This is, was and will always be taken into account when building
tall structures made from connected lengths of column. You simply have
to. If not, even regular atmospheric temperate will cause problematic
expansion.
Building fires in the past have burnt on numerous
floors and this thermal expansion never caused them to fall. Remember
that the nuts, bolts and brackets holding the steel frame together, will
also heat and expand. The related fixings are all of the same metal
because using a different metal will cause contact corrosion. "
Yes. I'm sure architects are aware of vertical thermal expansion, but I'm pretty sure they can't imagine or plan for every conceivable scenario that could occur that would endanger a buildings structural integrity.
To quote NIST
Factors contributing to WTC 7's collapse included: the thermal expansion
of building elements such as floor beams and girders, which occurred at
temperatures hundreds of degrees below those typically considered in
current practice for fire-resistance ratings; significant magnification
of thermal expansion effects due to the long-span floors in the
building; connections between structural elements that were designed to
resist the vertical forces of gravity, not the thermally induced
horizontal or lateral loads; and an overall structural system not
designed to prevent fire-induced progressive collapse.
The building design was unique compared to other buildings that had suffered significant long duration fires with inoperable sprinkler systems. Had the sprinkler system be in operation the design of the building would not have mattered and the building would not have collapsed. Just because something has not occurred before does not it mean it can't happen.
"Now, you'd also have to take a look at the consequences of the report, to understand how seriously it was taken.
Here
you have a report that suggests most of the buildings in New York,
indeed America and the rest of the world, are at risk of total collapse
if exposed to a multiple floor fire for more than a handful of hours.
Now
the question, how much retrospective thermal proofing and structural
bolstering has been mandated as a result? It would make sense, no? I
mean, considering that all these buildings would lose massive safety
rating chunks which would have to be brought back up to acceptable
standards"
The report does not suggest, most of the building in New York, America or the world are risk of a total collapse. See section 12 in the NIST FAQ, where it address the issue if potentially thousands of other buildings are at risk.
"While the partial or total collapse of a tall building due to fires is a
rare event, NIST strongly urges building owners, operators, and
designers to evaluate buildings to ensure the adequate fire performance
of structural systems. Of particular concern are the effects of thermal
expansion in buildings with one or more of the following
characteristics: long-span floor systems, connections that cannot
accommodate thermal effects, floor framing that induces asymmetric
forces on girders, and composite floor systems, whose shear studs could
fail due to differential thermal expansion (i.e., heat-induced expansion
of material at different rates). Engineers should be able to design
cost-effective fixes to address any areas of concern identified by such
evaluations."
They they go on to list measures that could prevent future collapse in a similar situation.
"Just one of these strange variables would be enough to warrant an investigation. And
the basic result from NIST was, a bunch of anomalies and first time
evers, resulted in a completely abnormal situation occurring."
I would find it much stranger, that the conspirators would have been able to plant demolition explosives undetected. Remember no one was killed in the 7 WTC collapse as they all already evacuated due to the attacks on the towers. Everyone who worked in that building survived, yet did any of them say they saw demolitions being planted? Where the conspirators that advanced that they where able to calculate/predict that the collapse of the main towers would cause debris strikes that caused fires of significant magnitude in 7 WTC that could provide cover for a controlled demolition, that the conspirators where able to hide both the visual and audio signs of controlled demolitions that can be seen and heard in virtually any video of a controlled demolition. We also have the issue that the collapse does not follow the typical collapse pattern of a controlled demolition.
"Now the question, how much retrospective thermal proofing and
structural bolstering has been mandated as a result? It would make
sense, no? I mean, considering that all these buildings would lose
massive safety rating chunks which would have to be brought back up to
acceptable standards.
Remember, if another building collapses
because of fire, there will be heads rolling up and down the block in
the offices of town planners and safety authorities.
Then also
have a look at how insurers have approached this. Because you bet, if
this report was correct, their risk just went up tenfold, and there's an
enormous incentive in it for them. They could not raise their premium,
because the logic behind NIST is clearly flawed and would never stand up
in court."
Do a quick google search and you will see changes to building regulations and fire codes have been implemented due to 9/11.
Perhaps insurance premiums did go up. Did you check?. Searching around the internet it seems before 9/11 insurance against terrorist attack was offered for next to nothing because it was considered so remote. After 9/11 insurances companies refused to provide cover against terrorist attack for any price, so much so the government had to step in.
Note the odds of a terrorist attack similar to 9/11 have decreased due to greater security at airports and cockpit doors being locked to prevent hijackers taking control of planes.