For those who are interested, my article is at:
www.journalof911studies.com/letters/wtc_mass_and_energy.pdf [link added]
After reading my paper, I think most people will understand that:
- The point of the paper is that the values provided by Port Authority, Wikipedia, etc. are not backed up by any data.
- I calculate the weight of the towers based on design data provided by FEMA and NIST.
- All data is clearly referenced.
- My paper has nothing to do with Ross.
- My value for the total mass of one tower is 254,000 metric tons not 235,000 as stated by Sylvester.
- Sylvester is insinuating that my purpose is to reduce the potential energy. The lower potential energy (which happens to be very close to FEMAs) was not my goal, rather it was my result.
- The mass given by Ashley, Bazant and
Zhou, and Wikipedia (500,000 short tons) is nearly 80% more than the actual mass of one tower. Do the math Sylvester.
Thus if anyone is confused it is surely Sylvester.
Nonetheless Sylvester does have one point. I use the density of A35 steel while many grades of steel were used in the towers. I'm not really sure if higher grade steels are more dense, but I doubt it. Anyone?
Others have pointed out a few error sources in my calculation and I have found a few myself which I will share here:
- I have omitted the hat truss and antenna.
- I included all steel in the scaling by floor when actually none of the floor assembly steel should be scaled
All of these errors affect except the antenna effect only the PE and not by a huge amount. I am interested in any comments and will be updating my paper soon.
Here's a few.
First, I looked through your paper and find it sorely lacking in detail. I'll buy your steel estimate, but that's as far as I'll go.
Did you take into account:
- Steel trusses on each floor?
- Gypsum and insulation packed around the columns?
- Spandrel plates?
- Aluminum cladding?
- Windows?
- Utilities?
- Elevators?
- Cross-braced steel? (Largely below the 8th floor)
There is quite a bit more design information than you used here provided in NIST NCSTAR1-1, and even that falls short of a full blueprint.
As for the figures you
did include, there is one that leaps out at me:
Gregory Urich said:
Superimposed dead-loads in the WTC towers are considerably higher in the so called mechanical floors. This is however ignored for simplicity and an average superimposed dead-load is approximated and distributed throughout all floors. The design documents give a superimposed dead-load of 8 psf for most floors outside of the core.8 This value is most likely larger than the actual loads but is used for all floors to take into account the much larger actual loads of the mechanical floors.
And your reference, footnote 8, is to NIST NCSTAR1-1. Well, I've read
NIST NCSTAR1-1, and I don't see any support at all for your 8 psf assertion.
In fact, if you turn to Table 4-1 on page 45 of that report (page 105 in the browser), you see a table of typical dead loads according to code. In that table, you'll see
acoustic ceiling tile, all by itself, is 2 psf. Yep, that popcorny stuff. You think
everything else that was nailed down weighed only three times what the ceiling tiles did? Why?
A better reference would have been
NIST NCSTAR1-2A, chapter 4. On Page 70, they explain how just steel floor framing alone totalled 7 psf on Floor 75, and 6 psf on floor 96. That's
actual load, not prior to load reduction calculations in design rules. Then on Page 71, they add 20 psf for partitions, and on Page 72 they add another 20 psf for concrete beam enclosures. You get the idea.
I reject your figure and demand a more detailed accounting. Since you cited the NIST report, how did you get this figure out of it?
Similarly, your live load figures are not credible:
Gregory Ulrich said:
Live-loads
Live-loads are approximated using 1/4 (as used by NIST) the maximum design loads.
Where did NIST use a factor of 1/4th? I don't find that assertion anywhere in NIST NCSTAR1-1, 1-2, or 1-2A where they built their structural model. For that matter, I don't recall seeing it anywhere in the report.
You'll have to explain where you got this, too. I don't see it, and I don't believe it. Several times the Port Authority
strengthened parts of the Towers in response to tenant requests and heavy loads. This is hardly what would have taken place if the structure had 75% reserve capacity.
The only place I've seen a "Safety Factor of 4" posited before, anywhere, is from Gordon Ross. And he's a
fraud.
Now, then, some questions for you:
1. Why did the designers overestimate the mass so badly?
The NIST report describes why the steel was sized the way it is, and it's sized to support the weight they claim. So you are also supposing that the Tower designers must have overbuilt their structure by a factor of two on top of all code requirements... You really think the designers were that stupid? Convince me.
2. Why would anyone bother misstating the tower mass?
Overestimating the tower mass does not help with any coverup. The tower mass does not affect the destruction seen once it started to collapse. This is because potential energy scales linearly with mass, but aggregate toughness scales linearly with mass, too.
In terms of collapse initiation,
Dr. Bazant has demonstrated that the impact was
eight times what the remaining tower could possibly absorb. A factor of two won't solve this problem for you, even assuming the Tower was lighter but full strength.
One of the validations performed in NIST NCSTAR1-2 is matching the natural frequencies of the Towers to those measured over their lifetimes by accelerometers. This is summarized in Table E-2 on page xlvi of that report (page 48 in the browser), and handled in detail in Chapter 3.2.11 of NIST NCSTAR1-2A.
The frequencies were computed with full dead loads but no live loads, reflecting the cleanest real-world data when occupancy was at a minimum, i.e. nobody running around to screw up the accelerometers.
So here's the question. The natural frequency is a function of the elasticity and of the weight (structure plus dead loads). If NIST got this part of the weight wrong, why does their model match actual measurements? If they were anywhere near as far off as you claim, they wouldn't be close.
4. How was your paper reviewed?
I've shot down quite a few papers that appeared in the
"Journal" of 9/11 Studies, with the most embarrassing probably being
this one. So far, I see a forest of question marks around your paper as well.
All the questions I've raised above would be brought up instantly in a legitimate peer-review process. So, have you heard these complaints before? What questions
did you get about your paper? Who reviewed it, when, and how were corrections handled?
I've always been curious just how the
"Journal" works. Since you are just a BS ECE and probably new to the world of publication, I can hardly fault you if you're unfamiliar with how the real journals operate, and would be glad to explain if you are curious.
Looking forward to your response.
