One of the biggest issues for 9/11 truthers seems to be their difficulty in comprehending how the crashes into the two main towers could have eventually caused the collapse of a third building.
Perhaps that is because NIST is not at all clear on just how that happened. Maybe you can explain it to us.
NIST in their report says that physical damage to the WTC 7 by the towers was NOT a cause of collapse or failure.
Why you defend a position that even NIST gave up on is beyond ignorant.
They don't even have a substantiated position on how the fires in WTC 7 even started.
The NIST authors have not proven their hypothesis regarding the fate of WTC 7, and the NIST conclusions are not based on physical evidence that can be tested and confirmed by others.
They frequently use the term " probable collapse sequence" to describe their hypothesis, but their report never quantifies this probability.
FEMA concluded that a fire induced collapse had only a low probability of occurrence.
Various hypotheses were considered for the initiation of complete global collapse. The possibilities considered by NIST included
(1) a fire-induced local failure leading to vertical and horizontal failure progression throughout the entire structural system, (2) a
fire-induced failure from burning diesel fuel leading to complete global collapse, and (3) a blast-induced demolition scenario.
According to NIST:
The leading hypothesis for the failure sequence that characterized
the initial local failure was based on fire-induced failure events in the
tenant floors.9
A heat-induced column failure hypothesis was quickly ruled out after concluding the fires were not hot enough for the duration of
time required to reduce the steel strength by 50 percent.
Therefore, it would not have been possible for a building contents fire to have heated a massive, insulated column such as Column 79 to the point of failure.10
In its brief dismissal of the controlled-demolition scenario, NIST argues that careful preparation of columns for demolition could not be accomplished without detection, and ''Controlled
demolition usually prepares most, if not all, interior columns in a building with explosive charges, not just one column."12
While NCSTAR authors imply that demolition of multiple columns would be required and unlikely, the same authors conclude that the
buckling failure of a single column was sufficient to trigger a complete progressive collapse of the entire building. If a single-
column failure could bring the entire building down, it does not matter how that column was removed.
If a man-made collapse required extensive preparation to
deliberately break every column on multiple floors, then a "natural" single-column failure could not possibly cause rapid, symmetrical,
and complete global collapse—straight down in classic controlled-demolition style.
Observations for WTC 7 do not
match the typical sequence of events
for a controlled demolition.
This collapse sequence is
inconsistent with a typical controlled
demolitionÂ…
13 --NIST
There are thousands of alert and well-informed citizens worldwide, including scientists, demolition experts, architects and structural engineers, who disagree with the preceding statements.
Furthermore, the collapse sequence referred to by NIST is the
one taking place during their computer simulation—a sequence of events invisible to witnesses and, to a significant extent,
under the control of NIST analysts.
Only fire-induced floor-system failure was seriously considered by NIST as the cause of collapse initiation. Abundant and well-
documented evidence suggesting the controlled demolition of WTC 7—including news videos, witnesses hearing explosions,
foreknowledge of the collapse, first-responder reports of molten metal in the debris, extreme surface temperatures recorded by NASA thermal imaging for weeks following the collapse, and evidence of melted structural steel—was simply ignored.14
It is difficult to imagine how anyone interested in establishing the likely technical cause of the building failure could
ignore evidence of a ''liquid eutectic mixture containing primarily iron, oxygen and sulfur formed during this hot corrosion attack on
the steel."15
This was obviously not caused by an ordinary fire consuming only building contents.
http://www2.ae911truth.org/downloads/NIST_Analyses_Brookman.pdf?format=pdf
