Deadline of Public NIST Comments Today

Just another reminder, if your going to comment on the NIST report get to it!

Here was what I sent in: To

Here was what I sent in:

To whomever it may concern,

I am a concerned citizen who has actively followed the investigation performed by the NIST into the collapses of WTC1, WTC2, and WTC7 on 9/11. Over time I have developed several questions which stick out in the collapses of these buildings. Unfortunately I have not been able to find any place in which your most recent release of documents addresses my questions.

It seems almost as if the issues and concerns I have are omitted as non-issues, perhaps because I am coming from the direction of questioning how the buildings actually collapsed instead of simply explaining the commonly accepted reasons behind the collapses.

In any event, one particular issue in your documents stuck out to me, and it leads to my most prominent concern with your report, namely the use of the term 'global collapse' without a detailed definition, and the avoidance of studying the intact structures which resided below the point of 'global collapse'.

These quotes from your document illustrate my point:

>From '', page 5:
Simpson Gumpertz & Heger Inc (SGH) developed global models of the World Trade Center (WTC)
towers using finite elements to gain an understanding of the roles of the aircraft impact damage and the
subsequent fires in the WTC towers with respect to structural stability and sequential failures of
components and subsystems and to determine the probable sequence of structural responses that let to
initiation of global collapse. The study was conducted as part of the investigation on the WTC disaster by
the National Institute of Standards and Technology (NIST).

>From '', page 169:
The parts of structures below the impact zones (Floor 89 to Floor 91 in WTC 1 and Floor 73 to Floor 77
in WTC 2) contributed little to the overall behavior of the buildings. Previous analyses of subsystem
models and preliminary global models showed that the elements below the impact zone did not
experience plastic deformations or buckling. Therefore, they were eliminated to further reduce the size of
the models. With this modification, the global model for WTC 2 was truncated at Floor 77 just above the
mechanical floors and at Floor 91 for WTC 1.

Perhaps I am misreading the above, but it sounds as if aside from studying the initial reasons for collapse, the rest of the building was not considered. This is particularly of concern to me because while I find your research into the initiation of 'global collapse' somewhat convincing, I can find no relevant definition of the term 'global collapse', and no explanation as to how the remaining structure below this point was demolished so quickly and thoroughly. Were the term 'global collapse' a commonly understood term regarding steel buildings I would not find this omission so notable, but in my research I have yet to find any historical examples of such a 'global collapse' in regards to a steel superstructure.

I would like to know specifically what sections, if any, of your report explain the 'global collapse', and its mechanics.

Here are my specific concerns:
1) How could 77 floors of intact superstructure in WTC2 and 91 floors of intact superstructure in WTC1 be considered as 'contributing little to the overall behavior of the buildings'?
2) What resistance should the remaining intact superstructure have provided in this 'global collapse'?
3) What energy from the 'collapse' would have been spent in destroying the remaining super structure?
4) Is the incredible speed of 'global collapse' (approximately 10 floors per second) within reason given the massive superstructure which laid directly underneath the 'collapsing' floors?
5) How does the time it took for the 'global collapse' relate to the speed of a free fall with no resistance at all?
6) Is it reasonable to suggest that 77 floors in WTC2 and 91 floors in WTC1 were destroyed at near free fall speeds with the remaining superstrucutre providing virtually no resistance to the speed of the collapse?

I had hoped that the NIST might take the same amount of time spent in explaining the 'global collapse' as it spent in how that 'global collapse' started, unfortunately that appears not to be the case. Given the incredible speed of the virtually symmetrical 'collapses', and the lack of historical context for such 'global collapses' with steel superstructures, I would think it would have deserved even more time than postulating on what might cause such a 'global collapse' across only a very small segment of floors in these massive superstructures.

I look forward to your upcoming report on WTC7, and I hope that you might consider addressing the energy necessary, and the time it should have taken, to completely obliterate 77+ floors of intact superstructure in both towers only from fires on a set number of floors.

Thank you for your consideration,

Roger Peters