lol why the fixation with Mr Gage and ae911truth. I mentioned ae911 in response only.And why would i need a grant? We are talking about some youtube videos that i narrated. Do you need a link to them? Well done on surveying all those engineers though. Did you get a grant to do that? Did you publish that in a paper? You're right about one thing, this is funny stuff, I'll grant you that.
WTC7 and the girder walk-off between column 79 and 44
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lol why the fixation with Mr Gage and ae911truth. I mentioned ae911 in response only.And why would i need a grant? We are talking about some youtube videos that i narrated. Do you need a link to them? Well done on surveying all those engineers though. Did you get a grant to do that? Did you publish that in a paper? You're right about one thing, this is funny stuff, I'll grant you that.
ozeco41
Philosopher
Finite Element Analysis.
It is a numerical calculation technique which can be used to analyse complex systems including structural systems such as the frames of WTC1,2 &7.
So tfk has correctly identified that is is an appropriate technique.
There is a problem facing the claims of C7 and gerrycan - see my previous posts.
It won't work if you either take a single member in isolation OR ignore several factors. It has to be applied to the whole system (Or to be pedantic, to a part system with well defined boundaries.) And that is the stage that C7 and gerrycan are currently at - they are declining to take the "girder attached to two columns and some floor" and consider in in the full setting of all of WTC7.
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"Structural systems expressly designed to prevent progressive collapse, which is the spread of local damage from a single initiating event, from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it. Current model building codes do not require that buildings be designed to resist progressive collapse."
From, http://www.nist.gov/public_affairs/releases/wtc-082108.cfm
So, what 'single initiating event' do NIST cite for the destruction of WTC7 ?
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DGM
Skeptic not Atheist
You have ANSYS that you can use for free? Before you wanted NIST to release the ANSYS inputs that they "fudged." Why, if not so you and your learned engineers (whom you refuse to describe or name) could run the ansys yourselves?
eta -
Who's "we" with the ANSYS set up?
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You don't know about FEAs.
They had a huge model. The art to FEAs is to simplify all the aspects of the model that one can justifiably simplify. That means, take out parameterized variables if they are not significant to the results.
A coefficient of expansion that is a function of temperature represents a non-linearity in the analysis.
NIST says (pg. 460) "Nonlinearities in the analysis … required small time steps to complete one equilibrium iteration. For this reason, simulation of a 30 min temperature time history sometimes took several weeks to complete … and a complete ANSYS analysis for a given thermal case took approximately six months…"
Something as simple as changing a coefficient of expansion from a function of temp to a constant can allow a large model to converge 4 - 10 times faster.
It probably took days to weeks to run a single iteration. The difference between 4 weeks & 40 weeks … uh, matters. The difference between 6 months & 5 years matters. The error of 2 - 5% does NOT matter.
Your comments betray a lack of understanding of thermodynamics.
Tell ya what, Gerry.
Put a steel frying pan on the left front burner of a gas stove, put a 2" thick concrete block on the right front burner.
Turn both burners on full, and press one hand firmly onto each. Wait 2 minutes.
Tell me how important it is that the steel & concrete will end up at the same size. Thermal conductivity matters to the bulk temperature, and therefore to the DYNAMIC expansion (time) rates.
Concrete expands at a similar EXPANSION rate (inches / degree), but it does not heat up at anywhere near the TIME rate (degrees / minute) that steel does.
Thermal conductivity of steel is >200x that of concrete (43 vs 0.2 W(m °C). The heat will soak thru the bulk of the steel while it remains on the surface of the concrete.
When subject to fire, the steel conducts the heat at such a high rate, that it will fully expand in seconds (if not insulated) to minutes (if insulated), while the concrete will take hours for the heat to slowly soak thru it.
The DYNAMIC (not static) situation is that, to a high level of accuracy, the steel will be across the finish line (i.e., fully expanded) before the concrete gets out of the blocks.
No, it will not.
The concrete is an excellent thermal insulator. It is identical to the thick foam insulator that you put around your "to go" cup of coffee. The insulator does not suck (any significant amount of) heat away from the coffee PRECISELY BECAUSE it is a poor thermal conductor.
The floor pan is corrugated & tied to the concrete with shear pins.
If you cannot understand what that means in terms of its thermal expansion, then there is no point in talking to you about any of this.
Thermal expansion of the floor pans would have brought it OUT of contact with the concrete, significantly reducing its heat conduction to the concrete.
The gross lateral expansion of the floor pan perpendicular to the corrugation direction would have been equal to the concrete's expansion (i.e., DYNAMICALLY zero, ultimately equivalent to the concrete's, and unrelated to steel's).
The floor pan's expansion parallel to the corrugation direction would have likewise been equivalent to the concrete's, because the corrugations would have simply twisted & buckled under the restraints of the shear pins.
They are professionals.
You are an amateur.
And it's got nothing to do with "taking more time". It took much more human time to fine tune the analysis to run in a reasonable amount of computing time.
It is entirely possible that they may have gotten NO answer if they didn't take these steps. (Possible that the dynamic, non-linear equations may not have converged.)
They did it right.
You are evidently not competent to understand why.
No, you're wrong. That's not what I mean.
Are you going to answer any of my questions?
I agree.
They had a huge model. The art to FEAs is to simplify all the aspects of the model that one can justifiably simplify. That means, take out parameterized variables if they are not significant to the results.
A coefficient of expansion that is a function of temperature represents a non-linearity in the analysis.
NIST says (pg. 460) "Nonlinearities in the analysis … required small time steps to complete one equilibrium iteration. For this reason, simulation of a 30 min temperature time history sometimes took several weeks to complete … and a complete ANSYS analysis for a given thermal case took approximately six months…"
Something as simple as changing a coefficient of expansion from a function of temp to a constant can allow a large model to converge 4 - 10 times faster.
It probably took days to weeks to run a single iteration. The difference between 4 weeks & 40 weeks … uh, matters. The difference between 6 months & 5 years matters. The error of 2 - 5% does NOT matter.
Your comments betray a lack of understanding of thermodynamics.
Tell ya what, Gerry.
Put a steel frying pan on the left front burner of a gas stove, put a 2" thick concrete block on the right front burner.
Turn both burners on full, and press one hand firmly onto each. Wait 2 minutes.
Tell me how important it is that the steel & concrete will end up at the same size. Thermal conductivity matters to the bulk temperature, and therefore to the DYNAMIC expansion (time) rates.
Concrete expands at a similar EXPANSION rate (inches / degree), but it does not heat up at anywhere near the TIME rate (degrees / minute) that steel does.
Thermal conductivity of steel is >200x that of concrete (43 vs 0.2 W(m °C). The heat will soak thru the bulk of the steel while it remains on the surface of the concrete.
When subject to fire, the steel conducts the heat at such a high rate, that it will fully expand in seconds (if not insulated) to minutes (if insulated), while the concrete will take hours for the heat to slowly soak thru it.
The DYNAMIC (not static) situation is that, to a high level of accuracy, the steel will be across the finish line (i.e., fully expanded) before the concrete gets out of the blocks.
No, it will not.
The concrete is an excellent thermal insulator. It is identical to the thick foam insulator that you put around your "to go" cup of coffee. The insulator does not suck (any significant amount of) heat away from the coffee PRECISELY BECAUSE it is a poor thermal conductor.
The floor pan is corrugated & tied to the concrete with shear pins.
If you cannot understand what that means in terms of its thermal expansion, then there is no point in talking to you about any of this.
Thermal expansion of the floor pans would have brought it OUT of contact with the concrete, significantly reducing its heat conduction to the concrete.
The gross lateral expansion of the floor pan perpendicular to the corrugation direction would have been equal to the concrete's expansion (i.e., DYNAMICALLY zero, ultimately equivalent to the concrete's, and unrelated to steel's).
The floor pan's expansion parallel to the corrugation direction would have likewise been equivalent to the concrete's, because the corrugations would have simply twisted & buckled under the restraints of the shear pins.
They are professionals.
You are an amateur.
And it's got nothing to do with "taking more time". It took much more human time to fine tune the analysis to run in a reasonable amount of computing time.
It is entirely possible that they may have gotten NO answer if they didn't take these steps. (Possible that the dynamic, non-linear equations may not have converged.)
They did it right.
You are evidently not competent to understand why.
No, you're wrong. That's not what I mean.
Are you going to answer any of my questions?
I agree.
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I might be fixated on making silent computers, but my "fixation on Mr Gage" ends with knowing his claims are the same as yours, evidnece free. Gage spreads lies, and you don't care, you call his followers patroits.
A&E, is a scam. If you can't figure that out, how can you expect someone to take your claims serous, or your work?
Thought you were trying to expose the truth, it takes money.
I thought you had something.
sure
I am an Engineer. I have worked with and gone to school with thousands of engineers. None of us endorse Gage, we out numbers Gage's engineers! If Gage was right we would all support him. Gage is wrong, he has nothing. Simple math shows Gage has the support of 0.01 percent of all engineers. If you wish to survey all engineers, it will only destroy your fantasy, and expose what you think are patriots, are plain old paranoid conspiracy theorists. If you wish to prove my math wrong, go ahead make my decade. You have failed to go get the help of independent engineers, if you had you would not be calling people who blindly support Gage's lies patriots.
I don't need a grant, you do.
Fire did it? Not needed, it is clear from the evidence. You are the one who thinks we need another paper. Why can't you do it? Are you claims backed with evidence? If I thought something was wrong on 911, I would publish a paper and prove my claims with evidence. What is stopping you and 1600 patriots? evidence?
Calling 1600 paranoid conspiracy theorists patriots is silly. You are funny.
Does this mean you will not be doing a paper to prove your claims? You have claims, why can't you prove them? Do you have claims? Thermite? How will you prove thermal explanation did not do it? You realize there is more to it?
Gage has made over 1,000,000 dollars in the name of truth, and he has done nothing but fool you and others into thinking A&E are patriots.
What is your claim about the cause of WTC7; right, you want a new study! Not needed. But if you try, there are many who have studied WTC 7, but you will not find them with google. Try real research.
WTC 7 collapsing on 911 is not unexpected after burning all day with zero firefighting. The only buildings which survive fires, are those which are fought, and even when fought, fires have totaled many buildings. What is your big picture claim?
Absolutley none of your business.
Sunstealer
Illuminator
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- 3,128
What are the values that you ascertain to the different parts of the structure and therefore the heat difference that will allow such a calculation?
You seem to be making bold assertions without backing them up with figures or indeed a model of your own.
This is why people ask for your credentials and evidence of your knowledge. We have already seen on this thread C7 boldly state that expansion of steel is not "lineal" even though the spreadsheet he quotes uses the linear coefficient of thermal expansion for steel to determine the level of expansion. That's why, as a metallurgist, I picked up on it knowing it was a false statement.
If you wish to talk about thermal conductivity and how that affects the particular feature of the girder attached to Column 79, then you will have to not only provide details of the temperature differentials across the structure, but also how you have arrived at those values.
Subsequently you will have to show how that affects the structure with regard to the girder giving (or removing) lateral support to column 79.
If you give a short answer, devoid of mathematics or detailed analysis, then we can safely say that you don't have an answer. If you don't have an answer then what are you doing with your life?
I am willing to show you an animation. I cannot divulge the input data however. It just wouldn't be safe. Sorry. My humour is poisson.
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you tricked me. But i do agree with you that steel conducts much better than concrete does. So why did NIST not let it conduct in their FEA model?Sunstealer
Illuminator
- Joined
- Oct 22, 2007
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Non Sequitur. Just because they have not released data doesn't mean that they didn't perform the analysis. You are sounding like the stereotypical paranoid truther.
Oh they performed an analysis. It just cant be reiewed by anyone because they just show you the answer and not the working. I used to get told off for that when i was 5. Releasing an animation is not an FEA analysis that can be verified. Releasing the inputs that created that animation is. NIST are therefor saying 'trust us' . I prefer my science not to be faith based belief, but repeatable, open and verifiable. How do you like yours?
OK, before i go to sleep, what about an FEA competition to break the monotony. We can all guess what it stands for ok. I'll go first, and you lot can follow along.
Fool Everyday Americans....... Fast Enigmatic Animations.....Forget Every Actuality....... Freefall's Easy Actually....... you get the idea. Your turn, g'night.
Fool Everyday Americans....... Fast Enigmatic Animations.....Forget Every Actuality....... Freefall's Easy Actually....... you get the idea. Your turn, g'night.
Sunstealer
Illuminator
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ozeco41
Philosopher
gerry you are copying C7's mistakes - two of them in your statement.
Why don't you simply pause for a couple of minutes - sleep on it overnight.
Several of us here know what we are talking about. Your continuing to repeat your error does not change the fact.
A large fire can destroy a building after being caused by a "single initiating event" such as striking a match. Think on that.
Now to push the analogy further. Your mistake is that you only have part of a match when you only consider less than half the factors affecting the girder and two columns situation. A match with no head won't initiate a fire.
Repeating the truism "...what 'single initiating event' do NIST cite..." doesn't change the fact that neither you nor C7 are properly defining the setting of that initiating event.
"So, what 'single initiating event' do NIST cite for the destruction of WTC7 ?" is not the question to ask. You are missing the point. And several of us are certainly not missing the point.
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