9/11 Physics from Non-Experts

[SYLVESTER1592]

I'm glad

Have you considered that Apollo, like myself may still be undecided on the collapse issue?

Over at the Scholars for 911 Truth and Justice Forum I am accused of being a misinformation agent, and worse. Here I am accused of being a twoofer, a liar and a fraud. It is tiresome but I'm learning not to take it personally. It seems to me that open minds and closed minds are found in roughly the same proportions (1:5 respectively) in both camps.

Nonetheless, my discussions here have helped me to understand what it takes to convince hard-core skeptics. This will help me immensely in improving my paper.

I’m glad.

As you may have noticed even hardcore skeptics are not divided into one camp, but the difference with believers is that skeptics are susceptible to reason and open themselves for debate (meaning they can be convinced when offered a better explanation or argument). This does mean they require proof or a method that will convince them, some of which have been described in this thread. I believe there are reasonable ways to provide proof and engage in debate, even when dealing with hardcore skeptics. Usually a careful stepwise method helps, but always limiting yourself to what is irrefutable.

For most researchers, stubbornness is a characteristic that is both a useful tool and a hurdle while doing research. It’s no real fault, but rather a result of diving into a subject in great detail. Crossing the line into belief is a fault, and that’s where skeptics come in handy. Fighting from the trenches without budging, will often provoke your opposition to do the same thing.

Eventhough, the forum may be hard on your paper, there is reason for it. It has little to do with what you believe, but it is a hurdle. As long as you separate your beliefs from your work, there is no reason why you can’t believe what you do, but it does make your work more difficult…
Especially in a much debated subject like this one, conclusions that overreach what you can prove beyond doubt, are better addressed with less certainty.

Doubt may be raised in a different level when something is in line with what you believe. In essence, for you as a researcher, the hardcore skeptics are on your side in the long run, eventhough you might not feel that way right now.

But I guess you figured that out by now…

Good luck

SYL

 

[GregoryUrich]

I have read many critiques of technical papers but cannot recall a single one which contained the phrase (or some variant) "I have more but this is just for starters". That is not the language of the intellectual; it is the language of the twoofers. Please, if you have more, take your time, consolidate it, and present it. If you do not have more, say so. I can wait for you to present a coherent complete and full critique. Please advise when your critique is complete and finished.

I didn't propose to write a formal critique. I thought we were having a discussion. If you don't want to talk about those points now, fine. If you do please note that my first point:

1. Bazant models the plastic energy for compression of the lower part of the structure as a spring. The upper part should also be modeled the same way (i.e. two springs exerting pressure on each other). At maximum compression there is enormous force applied to the debris between the springs which likely accounts for the ejection of so much debris. This is also an energy sink.

should read:

1. Bazant models the strain (elastic) energy for compression of the lower part of the structure as a spring. The upper part should also be modeled the same way (i.e. two springs exerting pressure on each other). At maximum compression there is enormous force applied to the debris between the springs which likely accounts for the ejection of so much debris. This is also an energy sink.

Right now I'm dealing with mass and PE, and rewriting my paper. That will probably keep me busy for a couple of weeks. I'll get back to Bazant when I get into the energy balance/collapse time analysis when I'm done.

 

[Belz...]

I thought we were having a discussion.

Really ? I thought we were discussing doctrine.

 

[rwguinn]

I didn't propose to write a formal critique. I thought we were having a discussion. If you don't want to talk about those points now, fine. If you do please note that my first point:



should read:

1. Bazant models the strain (elastic) energy for compression of the lower part of the structure as a spring. The upper part should also be modeled the same way (i.e. two springs exerting pressure on each other). At maximum compression there is enormous force applied to the debris between the springs which likely accounts for the ejection of so much debris. This is also an energy sink.

Right now I'm dealing with mass and PE, and rewriting my paper. That will probably keep me busy for a couple of weeks. I'll get back to Bazant when I get into the energy balance/collapse time analysis when I'm done.

Anybody know how you model energy as a spring? or a beam?or any physical element?
As a compressed (or stretched) spring, ok. Energy=ability to do work.A spring, in and of itself, has no energy. At least get your units correct, please?

 

[beachnut]

Dr Greeening said;
·An analysis of the energetics of the WTC collapse events has shown that the kinetic
energy of the aircraft collisions and the subsequent gravitational energy released by the
descending blocks of floors were quite sufficient to destroy the twin towers in the manner
observed. The use of explosive devices in either of the two towers is

The times calculated for the collapse of WTC 1 and WTC 2 show good agreement with
the observed collapse times verifying the basic assumptions of the momentum transfer
model used in the calculations.

The kinetic energy of the collapse events was sufficient to crush the WTC floor
… with the observed WTC debris particle size distribution.

From a consideration of the strength of the WTC columns, and the effective area of
support they provided, it is demonstrated that the conditions necessary for the initial floor
collapse were initiated by the aircraft impacts and made irrevocable by the subsequent
eccentric loading of the core columns. The fires that were initiated by the jet fuel spilled
within the towers certainly weakened steel in localized areas in the impact zones.
However, it is suggested that the total collapse of both towers would have occurred even
without the jet fuel fires.

Is Dr Greening a NISTIAN? Does Dr Greening support conclusions similar to NIST's?

I thought Dr Greening would present some insight into issues when he started to post.

I am still waiting for Dr Greening to post.

 

[Augustine]

I didn't propose to write a formal critique. I thought we were having a discussion.

Right now I'm dealing with mass and PE, and rewriting my paper. That will probably keep me busy for a couple of weeks. I'll get back to Bazant when I get into the energy balance/collapse time analysis when I'm done.

Ok, we are having a discussion. Why hold back on all your points of criticism of Bazant? Why not just put all your points out there, even if they are incomplete? Why try to hold some criticisms in reserve, as it is?

If it takes you several weeks to come up with more criticisms, so be it. As I have said, put it all out there, and we can discuss it. I assumed when you said that Bazant "doesn't hold up", that you had complete criticisms.

While we are waiting, if I may offer some advice, I would advise you to begin asking the question "So what?" - to start identifying what errors are significant, and which are largely irrelevant (or insignificant). I would also advise you to do some serious calculations of the sensitivity of your numbers (and others), and start thinking about accuracy. Bluntly, I will tell you that your claims of +/- 3% accuracy for your weight calculations cannot be supported unless your sources for your calculations are rather more substantial than what they are now.

 

[GregoryUrich]

Ok, we are having a discussion. Why hold back on all your points of criticism of Bazant? Why not just put all your points out there, even if they are incomplete? Why try to hold some criticisms in reserve, as it is?

If it takes you several weeks to come up with more criticisms, so be it. As I have said, put it all out there, and we can discuss it. I assumed when you said that Bazant "doesn't hold up", that you had complete criticisms.

While we are waiting, if I may offer some advice, I would advise you to begin asking the question "So what?" - to start identifying what errors are significant, and which are largely irrelevant (or insignificant). I would also advise you to do some serious calculations of the sensitivity of your numbers (and others), and start thinking about accuracy. Bluntly, I will tell you that your claims of +/- 3% accuracy for your weight calculations cannot be supported unless your sources for your calculations are rather more substantial than what they are now.

By the way, I believe I said I had issues with Bazant's paper, which is somewhat different than saying it "doesn't hold up". By the way I'm not holding anything back, it's more a consideration of how much time I can spend on this.

4. I calculated the deflection of the lower section (P/C) based on Bazant's numbers and got 0.23 m. This magnitude of deflection is into the plastic zone (this part of Bazant's model is pre plastic deformation) for one floor so the deflection must occur over several floors. I haven't tried to figure out how many. Regardless, for the deflection to occur mass must be moved hence there is energy associated with momentum transfer.

5. In his derivation of Pdyn/Po, I think Bazant equates the design load capacity(mg) with his assumed mass of 58,000 tons (times g) for the upper part. I maintain there are two mgs one that should be used to establish the strain energy (mass1g) and one for design load capacity (mass2g). So the equation should really be:

Pdyn/Po = (1 + sqrt(1+2mass1gCh))/mass2g

6. Further, I believe 58,000 tons is overestimate for the mass of the upper part (mass1) by a factor of ~2.9 according to my work. His design load is also an underestimate of ultimare yield strength for the lower part. If I use my mass for the upper part and the 2.8 safety factor required by the code (refers to destructive testing of assemblies), I get Pdyn/Po of around 0.3 = no collapse. Don't forget, there is a sqrt on the upper part so it changes the ratio dramatically.

7. Bazant doesn't take into account the breaking up of floors and such (so called "pulverization") which does consume a considerable amount of energy. I'm not saying every ounce of concrete was pulverized to fine powder but a certain amount of crushing and breaking did occur.

8. Bazant doesn't take into account the ejection of material which even some NIST friendly sources put at 80-90%. This also consumes energy and leaves less PE and KE to continue the collapse.

I did my calculations rather quickly the other night but I think they are correct. If I only had one issue I would ignore it but I think some of these issues are worth pursuing.

 

[Newtons Bit]

By the way, I believe I said I had issues with Bazant's paper, which is somewhat different than saying it "doesn't hold up". By the way I'm not holding anything back, it's more a consideration of how much time I can spend on this.

4. I calculated the deflection of the lower section (P/C) based on Bazant's numbers and got 0.23 m. This magnitude of deflection is into the plastic zone (this part of Bazant's model is pre plastic deformation) for one floor so the deflection must occur over several floors. I haven't tried to figure out how many. Regardless, for the deflection to occur mass must be moved hence there is energy associated with momentum transfer.

5. In his derivation of Pdyn/Po, I think Bazant equates the design load capacity(mg) with his assumed mass of 58,000 tons (times g) for the upper part. I maintain there are two mgs one that should be used to establish the strain energy (mass1g) and one for design load capacity (mass2g). So the equation should really be:

Pdyn/Po = (1 + sqrt(1+2mass1gCh))/mass2g

6. Further, I believe 58,000 tons is overestimate for the mass of the upper part (mass1) by a factor of ~2.9 according to my work. His design load is also an underestimate of ultimare yield strength for the lower part. If I use my mass for the upper part and the 2.8 safety factor required by the code (refers to destructive testing of assemblies), I get Pdyn/Po of around 0.3 = no collapse. Don't forget, there is a sqrt on the upper part so it changes the ratio dramatically.

7. Bazant doesn't take into account the breaking up of floors and such (so called "pulverization") which does consume a considerable amount of energy. I'm not saying every ounce of concrete was pulverized to fine powder but a certain amount of crushing and breaking did occur.

8. Bazant doesn't take into account the ejection of material which even some NIST friendly sources put at 80-90%. This also consumes energy and leaves less PE and KE to continue the collapse.

I did my calculations rather quickly the other night but I think they are correct. If I only had one issue I would ignore it but I think some of these issues are worth pursuing.

4. This is something that is over-conservative in favor of collapse prevention. In reality, the columns would have buckled and bent inwards. Bazant provides some pretty picture of this. In this case, the energy required to completely bend the columns down to the floor deck is only 12%, so he ignores this energy.

Bazant also allows the whole building to have no yield point, and hence not go into plastic deformation. The spring is ALWAYS elastic and hence requires more energy to deform.

I do not think the movement of the masses along the height of the building is really significant.

5. This is something that I have a problem with as well. He assumes the design load of the beams is only the mass of what is above. In reality it should be at least 1.65 and probably in the 2 to 4 range.

6. The "factor of safety" for allowable stress design of a column is 1.65. I do not know where you got this 2.8 number from, it is fake. This "factor of safety" is based upon a Dead + Live (full design capacity) and having a capacity/demand ratio of 1.65. However, upon earlier analysis, many of the core columns did not meet this. They had a real "factor of safety" of somewhere in the 1.4 to 1.5 region.

7. He also doesn't take into account the massive lateral loads caused by eccentric connections and p-delta effects, and oh yea, the fact that the columns did not fall directly on top of each other. This is a simplified analysis, remember? Concrete is also very brittle, it doesn't take near as much energy to break it as steel does.

8. The initial impact would likely have little from the mass above. After the impact, most of the upper portion would have shattered and began to fall out, however.

 

[T.A.M.]

Apollo20:

Alot of what you interpret as "Stifling Debate" and harshness, likely comes from (A) long memories concerning your initial arrival to this forum, and (B) Overwhelming fatigue in dealing with the Woo.

I, like Mackey has said of himself, cannot speak for everyone, but I know I have personally been waiting for you to simply drop the crap and come out with your theory and the evidence to back it up. You may be tired of the tone you get from people here, and that is fair. I, however, and others I am sure, are tired of your condescending tone, and elitist attitude that you have displayed while posting here. Feel free at anytime to leave it at the door.

I am glad you are an intelligent scientist trying to find answers where you feel they are needed, but does that mean you are better than others here, or should minimize or outright ignore their comments and view points? No. We are not all chemists, but nor are you an aviation technician, or a Quantum Physicist...we all have our gifts, our areas, and not everyone is officially educated in them...

So we do not have a plethora of chemists for you to discuss your findings with...so what. You seem so secretive, not wanting to reveal the details in public, that having chemists here would likely not make much difference any way.

This forum is full of very smart, articulate people, as can be witnessed through reading many of the longer detailed posts here. Yes there is emotion, and frayed nerves, as there is in any community, cyber or RL. Your belittlement of this subforum and its posters, does little to further your case, but somehow I doubt that is your aim. I am not really sure, at this point, what your aim is here.

In a nutshell, why not just have out with it. If you believe the iron spherules are significant, than why? How? If there is some other theory you wish to propose, just out with it.

There is a poster that comes here occasionally, named Lyte Trip (5 weeks and a day by the way LYTE!!) who use to do the same before he released his video. He would hint at the content of his coming video...his evidence, claiming it was earth shattering, teasing, baiting people with it...I hope you are not like that.

Please take my words as sincere, as all I really want is to see you come here and have rational, intelligent discussions, and perhaps answer some questions us non-chemists may have.

Regards

TAM

 

[GregoryUrich]

...6. The "factor of safety" for allowable stress design of a column is 1.65. I do not know where you got this 2.8 number from, it is fake. This "factor of safety" is based upon a Dead + Live (full design capacity) and having a capacity/demand ratio of 1.65. However, upon earlier analysis, many of the core columns did not meet this. They had a real "factor of safety" of somewhere in the 1.4 to 1.5 region.
...

I'm probably using the term "factor of safety" incorrectly. Isn't there considerable reserve strength beyond the "factor of safety" based upon a Dead + Live (full design capacity)? As I understood the NIST section on the building code, testing is required at approx 2.8 times the full design capacity for some period of time (i.e. one week) and the elements and assemblies must not fail.

 

[Newtons Bit]

I'm probably using the term "factor of safety" incorrectly. Isn't there considerable reserve strength beyond the "factor of safety" based upon a Dead + Live (full design capacity)? As I understood the NIST section on the building code, testing is required at approx 2.8 times the full design capacity for some period of time (i.e. one week) and the elements and assemblies must not fail.

What you're thinking of is the floor joists, they were designed to be serviceable under dead+live (100 psf) conditions and not fail under dead + double live (200 psf).

The columns were designed for dead + reduced live load (depends on the column, but around 50 psf) and some of these did not even meet current code requirements for this. The actual ultimate strength of compression members is something less than the yield stress times the cross sectional area. After the axial force is greater than that, it buckled and starts bending. As it bends it can take an increasingly less axial force. There is no reserve capacity in a compression member like there is in a bending member. I go into it a bit in my blog post about Gordon Ross: http://newtonsbit.blogspot.com/

 

[Gravy]

8. Bazant doesn't take into account the ejection of material which even some NIST friendly sources put at 80-90%. This also consumes energy and leaves less PE and KE to continue the collapse.

Please post your sources for this claim. Thanks.

 

[Augustine]

By the way, I believe I said I had issues with Bazant's paper, which is somewhat different than saying it "doesn't hold up".

I've seen work by the twoofers that doesn't hold up, but Bazant doesn't hold up either.

This is what you said. Which is it?

2. I believe I have convinced most people that my linear scaling of steel mass is reasonable, although slightly in favor of a higher PE.

This is possibly the greatest source of error you have so far (and possibly the largest reason why you think Bazant is off by a factor of 3 in his mass). Linear scaling is not reasonable, because you are neglecting the simple fact that the majority (over 50% easily) of the steel mass is in the framing of the floor, which is constant over the height of the tower (except for the beam-framed floors, which I might be inclined to accept the assumption that their weight does not vary significantly from the truss floors). There is no magic percentage that one can assume for the weight of the columns relative to the total weight of the steel (columns + floor framing); it depends on too many factors to guess. I would ballpark that the weight of the columns could be 20% - 40% the total steel at each floor, but that is pulled from my nether regions and may or may not resemble reality. What I can guarantee you does not resemble reality is linearly scaling mass top to bottom.

Anyhoo, off we go...(numbering coincides with yours)
1. Insignificant. Remember, Bazant is merely demonstrating orders of magnitude. Go ahead and add a term. Show your assumptions and work it out, it will change nothing significantly. (Again, for the orders of magnitude we are talking about, +/- 20% is not very significant - it does not affect the final result.)
2. Is this the same as 4? Strain energy accounts for this movement.
3. At least half? No. Demonstrate this assertion.
4. Deflection is not over 1 floor.
5. Read the Addendum. No, only one mg.
6. Are you confusing pre-qualified load testing with factor of safety? Not the same thing. No evidence that I am aware of that any assembly from WTC was load tested - don't have to if you submit calcs. Interestingly, compare the load tests for prequalifying assemblies with completed construction. Newton is right on this.
7. Columns would buckle well before concrete was "pulverized". Define pulverized. Cite a source. Quantify the energy, and include it in the formulae where you think it belongs.
8. How much material do you believe was ejected? What is your source for this? Do you agree or disagree with the "fell within its own footprint" statement?

As Newton has pointed out, Bazant is actually very conservative in assuming all impact is transferred axially. As has been noted before, and as every engineer with blast or impact experience knows, local effects are more significant than global ones. Bazant illustrates that globally the building couldn't resist the collapse; start throwing in eccentricities, impacts occurring at connections as opposed to centroids, or along spandrels, and the structure has substantially less resistance. As I have said several times, Bazant is only taking a broad look, showing the orders of magnitude.

(One last thing - if you are going to throw around your numbers, please start showing all your assumed values.)

 

[GregoryUrich]

What you're thinking of is the floor joists, they were designed to be serviceable under dead+live (100 psf) conditions and not fail under dead + double live (200 psf).

The columns were designed for dead + reduced live load (depends on the column, but around 50 psf) and some of these did not even meet current code requirements for this. The actual ultimate strength of compression members is something less than the yield stress times the cross sectional area. After the axial force is greater than that, it buckled and starts bending. As it bends it can take an increasingly less axial force. There is no reserve capacity in a compression member like there is in a bending member. I go into it a bit in my blog post about Gordon Ross: http://newtonsbit.blogspot.com/

So if I understand this correctly, the code for elements with calculated loads is less stringent than for elements that are actually tested. I don't know anything about the methods of calculation prescribed in the code but this doesn't seem to make sense. For reference, the section I am referring to is NISTNCSTAR1-1 pg 72:

The pre-qualifying load tests are for members and assemblies.

 

[Augustine]

So if I understand this correctly, the code for elements with calculated loads is less stringent than for elements that are actually tested. I don't know anything about the methods of calculation prescribed in the code but this doesn't seem to make sense.

The pre-qualifying load tests are for members and assemblies.

The code is "less stringent", if you would like to call it that, for elements that you can analyze and demonstrate with calculations that it can support the design load with acceptable (code-authorized) levels of stress. If you cannot analyze an assembly, (or if perhaps an assembly will perform better than your ability to analyze it), you can prequalify it with load testing. However, the "factor of safety" will never be 2.8; clearly it will vary depending on the ratio of dead to live to superimposed dead, but the limits are between 1.5 and 2.5, most likely around 2.

How does this not make sense?

 

[GregoryUrich]

The code is "less stringent", if you would like to call it that, for elements that you can analyze and demonstrate with calculations that it can support the design load with acceptable (code-authorized) levels of stress. If you cannot analyze an assembly, (or if perhaps an assembly will perform better than your ability to analyze it), you can prequalify it with load testing. However, the "factor of safety" will never be 2.8; clearly it will vary depending on the ratio of dead to live to superimposed dead, but the limits are between 1.5 and 2.5, most likely around 2.

How does this not make sense?

Calculations are more likely to have errors than the results of actual tests.

 

[Augustine]

Calculations are more likely to have errors than the results of actual tests.

Compare and contrast the load testing provisions for pre-qualifying and for completed construction. Ask yourself why the provisions are different. Can you explain it? Can you think of why the provisions may be different? Which is closer to the "factor of safety" of design? Why?

 

[GregoryUrich]

Compare and contrast the load testing provisions for pre-qualifying and for completed construction.
1. Ask yourself why the provisions are different.
2. Can you explain it?
3. Can you think of why the provisions may be different?
4. Which is closer to the "factor of safety" of design?
5. Why?

1. Don't know.
2. No.
3. No.
4. Don't know.
5. Don't know.

This is possibly the greatest source of error you have so far (and possibly the largest reason why you think Bazant is off by a factor of 3 in his mass). Linear scaling is not reasonable, because you are neglecting the simple fact that the majority (over 50% easily) of the steel mass is in the framing of the floor, which is constant over the height of the tower (except for the beam-framed floors, which I might be inclined to accept the assumption that their weight does not vary significantly from the truss floors). There is no magic percentage that one can assume for the weight of the columns relative to the total weight of the steel (columns + floor framing); it depends on too many factors to guess.

A detailed calculation of the truss weight can be found here:

http://www.takeourworldback.com/911/911fires3.htm

The article is anonymous but appears very detailed and carefully worked out.

Floor trusses and steel decking come to 14,300 tons. We would need to add floor framing for the mechanical floors which I suggest might be twice as heavy was probably less than 1200 tons. All together 15,500 tons or 15.5% of the total value I used. I have stated previously that I will take this into account.

Do you think it is reasonable to scale the rest linearly? A few pages ago, I did a quick calculation that showed my plate thicknesses would be slightly greater than the NIST values in the upper part of the building.

 

[Furcifer]

Do you think it is reasonable to scale the rest linearly? A few pages ago, I did a quick calculation that showed my plate thicknesses would be slightly greater than the NIST values in the upper part of the building.

Could you please show this quick calculation? This doesn't appear to be reflected in your mass calculation.

 

[GregoryUrich]

Could you please show this quick calculation? This doesn't appear to be reflected in your mass calculation.

I am not sure I understand your question. If you mean the total mass, I have used 100,000 tons of steel. I use scaling to distribute the 100,000 tons of steel (less the grillages) throughout the building. No matter how it is distributed in the building it still adds 100,000 tons to the total mass.