Physics of 9/11...

Originally posted by Joey Canoli
You're insane if you believe that.

You could neither go twice as high, nor have twice the weight.

You're just talking out of your backward facing orfice.

M.S. as a measure of structural capacity: This definition of margin of safety commonly seen in textbooks[7][8] basically says if the part is loaded to the maximum load it should ever see in service, how many more loads of the same force can it withstand before failing. In effect, margin of safety is a measure of excess capacity. If the margin is 0, the part will not take any additional load before it fails, if it is negative the part will fail before reaching its design load. If the margin is 1, it can withstand one additional load of equal force to the maximum load it was designed to support (i.e. twice what it was designed to support).

\text[Margin of Safety]=\frac[\text[Failure Load]][\text[Design Load]]-1


Margin of Safety = Factor of Safety − 1

en.wikipedia.org...

I was wrong actually, an FOS of 1 means it could hold twice it's own weight, so I was being very conservative in my claim...The building was designed to hold itself plus people, furniture etc., so with a common FOS of 2, you do the math genius....

Now who's talking out of what now child?

[edit on 7/2/2010 by ANOK]

Originally posted by ANOK

Originally posted by Joey Canoli
You're insane if you believe that.

You could neither go twice as high, nor have twice the weight.

You're just talking out of your backward facing orfice.

I was wrong actually, an FOS of 1 means it could hold twice it's own weight, so I was being very conservative in my claim...The building was designed to hold itself plus people, furniture etc., so with a common FOS of 2, you do the math genius....

What a simplistic analysis.

You're insane if you believe that.

You could neither go twice as high, nor have twice the weight.

Originally posted by dudly
reply to post by jthomas

 

Why? good question. When i saw the planes first hit my first reaction was that those buildings are coming down. But when they did come down i was confused at how they could have came down without any major structural damage below the point of impact. Even with the amount of weight and force that gave way at and about the point of impact, it seemed to crush everything underneath at a alarming rate of speed following the path of greatest resistance. This to me seemed impossible. Not only the crushing of everything but the speed at which it happened.

With no stuctural damage underneath the point of impact, there should have been major resistance to slow the collapse of the building, if not stop it entirely, at least for a moment if not forever. I expected the bulding to fall using the path of least resistance, which would have been around the rest of the building.

when If first saw the explosion from the plane I figured just the top half would of collapsed and the steel would of been intact (the frame of the building). But the whole thing collapsed? Something seems fishy and then people hearing bombs explode as well.

Originally posted by Joey Canoli
What a simplistic analysis.

You're insane if you believe that.

You could neither go twice as high, nor have twice the weight.

Insane if I believe what? That a building is designed to hold it's own weight plus a certain amount above that? That an FOS of 1 means it can hold twice the load it was designed to hold?

I never said anything about going twice the height, only that the building can hold twice its design load with an fos of 1, with an fos of 2 it can hold even more. I didn't say you could technically make the building twice the height, that brings in a whole new set of physics.
I was just trying to make a point that as usual went right over your head.

Dude what is wrong with you, do you really misunderstand so much, or do you just come here to disagree with everything 'truthers' say regardless of what it is? Do you think by disagreeing it makes me wrong?

I have given it to you in black and white, the info I supplied proves what I said, why can't you just admit it?

Insane to believe what an FOS is? Are you kidding? You CAN read right? Then you explain it to us what the FOS means genius.


I think anyone reading these posts, other than your buddies, can see who's insane here....And you have the nerve to say everything 'truthers' say has been proven wrong? You must be extremely desperate to keep your job, or you're delusional.

[edit on 7/3/2010 by ANOK]

Originally posted by ANOK

I never said anything about going twice the height, only that the building can hold twice its design load with an fos of 1

And that's too simplistic of an analysis.

Just admit you're ignorant about engineering, and how a building's FOS is figured.

You've already admitted your ignorance about how 7's floors were attached.

You've exposed your ignorance about 7 having a core structure.

You've exposed your ignorance about how steel can fail at 250C.

This is just another to add to the list.

I predict that these failures will not affect you in the least.

reply to post by Joey Canoli


Allow me to explain just how much safety is really factored in when a building is designed. Admittedly I am not entirely familiar with the design codes used in America in the 60's, but not much has changed (most have become slightly less conservative) and engineers can work internationally with ease due to the very similar design codes (most are based off America's).

First of all we have strength of materials. Not all members have the same strength, the capacity of a number of members fits a statistically normal distribution. Instead of taking the average capacity as a design value, the lower 20th percentile value is used (meaning in a large sample 80% of the members will be somewhat stronger the conservative value used in design).

Now we have the estimation of the live (applied) loads (such as desks, people, archives etc). Engineers have to consider the worst possible live loading that has a reasonable chance of occurrence during the buildings design life (ie most amount of people per floor during a special event, how much office space could be loaded with heavy archives in the worst case etc). These estimated worst case live loads are almost always significantly over what actually occurs on a typical day.

As if that wasn't enough, finally comes the most significant safety factoring. There are many different factors and combinations depending on the load types being analyzed (such as wind and earthquake loading) but the most basic and typical is self-weight (G) plus live (Q) loading. In the code I use we factor 1.2G + 1.5Q (meaning the total design force is 1.2 times the estimated self weight plus 1.5 times the estimated live load). The theoretical (conservative) member capacities must exceed this design force (and usually do by ~5% or more).

The combination of all these conservative methods means there is a high probability that a very high (but technically unknown) factor of safety exists in all properly designed structures. We can't say what that was on 9/11 but I would suggest the live loading was slightly lower than typical and would not be surprised if the structure could have been able to support close to twice its self-weight, as many insignificantly loaded structures are able, but that is just speculation. The physics in the videos was well explained and we are all still waiting for someone to create an experiment that closely resembles what occurred on 9/11. Another researcher has even offered ten thousand dollars to anyone who can do this because he is confident it is physically impossible (without the aid of explosives). With such blatant evidence shown in the vids it seems OS believers who have watched them either are payed to believe what they believe, have a poor grasp of physical concepts or don't have the mental capacity to change their beliefs (which is actually quite difficult for the majority of the population) and instead focus on the large number of morons in the truth movement who make idiotic claims (disinfo?) about pods and holographic planes etc.


[edit on 11-7-2010 by Azp420]

Originally posted by Azp420

and instead focus on the large number of morons in the truth movement who make idiotic claims (disinfo?) about pods and holographic planes etc.

Not me. They're psychotic, and responding to them only re-enforces their delusions.

Instead, I choose to focus on other morons that:

1- don't know if the floors are supported by the ext columns in WTC 7 or not, and so make a ridiculous and moronic claim that it was only there to hold up the facade and windows, and as such, has no structural role.

2- don't know that WTC 7 had a core/ext column arrangement that was somewhat similar to the towers, and so make a ridiculous and moronic claim that it had columns throughout.

3- don't know that steel columns can fail due to moderate temp creep, if the loads are high enough, at temps as low as 250C in 1 hour, and so make the ridiculous and moronic claim that steel can't fail at 250C.

Originally posted by Joey Canoli
And that's too simplistic of an analysis.

No it is not, you don't understand building design and safety factors, period...

Too simple, how can it be too simple? You don't understand the simple explanation, so how would making it more complicated help you?

Too simple, OK then Einstein why don't you explain safety factor in your own more complicated words. You guys say the daftest things, anything to avoid the actual point and admit you're wrong...

Originally posted by Joey Canoli
1- don't know if the floors are supported by the ext columns in WTC 7 or not, and so make a ridiculous and moronic claim that it was only there to hold up the facade and windows, and as such, has no structural role.

OMG you like to take things out of context. That was from my comment that generally the facade of a building is not integral to the buildings ability to hold itself up. I said that generally the facade is only there to hold the windows, doors, etc., I DIDN'T say WTC 7 was like that, and it DOESN'T matter if it was or not, it doesn't change anything, but why should I expect you to understand that?

If the facade was load bearing you still have other columns to take up the load, ALL BUILDINGS ARE DESIGNED TO BE REDUNDANT, got that Joey?

You guys are good at picking irrelevant points in order to dodge the relevant stuff, but you need to try harder Joey

2- don't know that WTC 7 had a core/ext column arrangement that was somewhat similar to the towers, and so make a ridiculous and moronic claim that it had columns throughout.

Huh? Are you serious?



WTC 7 was not like the towers, and so what if it was, see my reply above. Your assumptions and confusion is getting old.

3- don't know that steel columns can fail due to moderate temp creep, if the loads are high enough, at temps as low as 250C in 1 hour, and so make the ridiculous and moronic claim that steel can't fail at 250C.

What the hell is 'moderate temperature creep'? Why couldn't it have been 'severe, or low temperature creep'? lol

The load has nothing to do with the steels failure. Buildings are designed to be redundant Joey, this means that they are not under any load that they cannot handle, plus at least a factor of 2 (Do I have to explain safety factors again?), so the components that make up the structure are themselves not under any load that they could not handle even IF they lost 50% of their load bearing capacity.
250 is not going to heat the steel enough to cause it to fail in an hour, we went over this already. Also again you completely fail to consider redundancy and load shifting to undamaged structure. Unless you claim ALL the steel reached 250 and failed at the same time?

You've also not answered as to how the outer walls all ended up on top of the building, you said only one wall did, I showed you all four did. So what is your explanation for that Joey debunker?....

[edit on 7/12/2010 by ANOK]

Originally posted by iamcpc

The logic of physics! Lets play (again) the twin towers physics game!
Lets do the math! Lets play the 9/11 physics game!
My brand of illogic involves PHYSICS!

Sources cited here:
www.abovetopsecret.com...

1 pound = 0.45359237 kilograms

a 110-150 ton 500 mile per hour airplane.

a 100,000 - 136,000 kg airplane Is traveling at 223 m/s

F=MA 2.23 million netwons of force.

355,00 newtons per square meter is the yeild strength of structural steel.

the wtc towers were 110 stories

450k TONS (total weight) / 110 stories = 4000 tons per floor.


The top 1/3rd of the WTC weighed about 120000 tons.

120k tons is 109,000,000 KG. falling downward at 9.8 m/s is

1,068,200,000 newtons = estimate of the amount of force in the falling top 1/3rd of the tower

2,230,000 newtons= estimate of the amount of force in the plane

1,068,200,000 / 2,230,000= 479 times the amount of force!!

If you hit each floor of the WTC with 4 110 ton 500 mile per hour airplane what would it look like????

A big pile of rubble!

Sorry, I just saw this post and had to comment. This is the kind of physics that comes from OS believers who don't really understand much about physics but claim they are experts.

Either a lot of values used are not defined and the values defined are not used, or more likely the values defined are used incorrectly. If it is the first case, then why not define the relevant values so we can check your work? If it is the second case, well that speaks for itself.

F=ma = 2.23MN. I can only assume you arrived at this by multiplying the 100,000kg mass of the plane by its 223m/s velocity (by the way you made a mathematical mistake if you did this, the result would be 22.3MN). But you have mistaken acceleration for velocity, they are not the same thing (or for some reason you spent the time to define a velocity which was not used and used an acceleration that was not defined). The correct value to use for acceleration would actually be whatever the rate of deceleration was that the plane underwent as it impacted the tower.

3500 N per square meter was given as the yield strength of structural steel. Depending on the grade used, modern structural steel actually has a yield strength of ~300000000 to ~500000000 or more Newtons per square meter, although in the 60s ~280000000 N/square meter was common. I cannot see where you have used this value in any calculations anyway, so can only assume it was defined to make you sound reputable, but wiki was given as the source so I don't know.

1,068,200,000 newtons = estimate of the amount of force in the falling top 1/3rd of the tower.

Not sure what you mean by the amount of force "in" the falling third. It contains energy, it cannot contain a force. Maybe check your definition of what a force is. You have tried to make it sound as though this is the force that would be exerted on anything that got in the way of the falling third. This is actually just the force exerted by gravity on the mass of the top third in-order to accelerate the falling top third at free-fall. It is an arbitrary value and hardly relevant to anything you are attempting to prove. Again, using F=ma, the correct mass was used but acceleration should have been taken as whatever the deceleration of the top third was as it impacted the rest of the tower (the jolts that the video was talking about). Of-course though, these jolts were non-existent. I don't expect the majority to understand this next part but because there were not impact jolts or deceleration as the top third impacted the rest of the structure (instead it continued to accelerate into it and through it!), the falling top third couldn't have actually exerted any force on the structure it "impacted". Due to the law of conservation of energy and F=ma, it could have only exerted a force if it underwent some kind of deceleration upon impact.

(continued next post)


[edit on 12-7-2010 by Azp420]

reply to post by iamcpc


(continued from previous post)

David Chandler has a video on youtube explaining this concept in detail for those interested but I don't have time to find the link at the moment.

2,230,000 newtons= estimate of the amount of force in the plane

This has been proven incorrect above...

1,068,200,000 / 2,230,000= 479 times the amount of force!!

...making this equation and statement doubly incorrect, as both values used are incorrect.

If you hit each floor of the WTC with 4 110 ton 500 mile per hour airplane what would it look like????

A big pile of rubble!

Probably, but all you have managed to prove is that your faith in the OS is not based on any sort of credible understanding of basic physics. The illogic you have displayed in this thread is ludicrous, such as this statement (I almost thought it was sarcasm):

All someone would have to do to assist with the collapse of the towers would be to put 15 or 20 pallets of office paper on one of the top floors. 15 tons of weight according to:
manuelsweb.com...
is 13636 KG.

When that starts to fall it would add 133,632 newtons of force. That's one hell of a push! Maybe even more energy that would be present in explosives! Not to mention that it would be a LOT LOT LOT LOT easier to hide paper in an office building than to hide explosives (or micronukes, or thermite)!

No. 134 kN is no way near "one hell of a push" and wouldn't even come close to the energy from explosives. To put this in perspective, the design live load on a 67 square meter floor area (small) of a timber residential dwelling is greater than that (based off my design code 2.0 kPa loading). 134 kN is an insignificant force in one of the tallest buildings in the world. You say each floor is 4000 tons. If the plane impacted one floor lower the difference in weight would have been 300 times greater than your paper conspiracy. Stop trying to use big sounding numbers to prove your point. It is no wonder a lot of people don't know what to believe when having to rely on what other people tell them and don't have the expertise to spot monkey science (like the member FOXMULDER147).

I stand by my statement previously posted:

With such blatant evidence shown in the vids it seems OS believers who have watched them either are payed to believe what they believe, have a poor grasp of physical concepts or don't have the mental capacity to change their beliefs.

By the way, I know you love citing sources for everything but I will not provide any (I could if I wanted to spend the time) as it all came from my everyday experience in the engineering field, plus my design codes are not available online.

edit:

120k tons is 109,000,000 KG. falling downward at 9.8 m/s is

I have assumed you meant to put m/s/s as the units as 9.8 m/s/s is the acceleration due to gravity. If you meant a velocity of 9.8 m/s then this it is incorrect to use this in the F=ma equation as acceleration and velocity are not the same thing.





[edit on 13-7-2010 by Azp420]

Originally posted by Joey Canoli

2- don't know that WTC 7 had a core/ext column arrangement that was somewhat similar to the towers, and so make a ridiculous and moronic claim that it had columns throughout.

Yes, the exterior columns were load-bearing, but there were columns throughout and there was no central core similar to the towers.

3- don't know that steel columns can fail due to moderate temp creep, if the loads are high enough, at temps as low as 250C in 1 hour, and so make the ridiculous and moronic claim that steel can't fail at 250C.

No steel structure in history has ever failed due to temperature creep. It would most definitely not fail at temps as low as 250C in 1 hour, especially as the structural members were all fire-proofed with a 2 hour minimum rating for stability and integrity. The relatively small, isolated pockets of fire in 7 were not even comparable to the raging infernos survived by numerous other steel structures in history.

every point that truthers bring up gets shot down. Every time.......

Shoot down this for me please, gunner. How does a top third third which is weaker (weaker because the top part of the structure is designed to support less weight that the bottom part of the structure as it has less floors above to support) than the bottom third (or at the worst I'll give you same strength) pulverize the bottom third without itself being pulverized at an equal or similar rate? Remember, for every action there is an equal and opposite reaction. You're not allowed to break this physical law in your explanation.



[edit on 13-7-2010 by Azp420]

Originally posted by Azp420

Yes, the exterior columns were load-bearing, but there were columns throughout and there was no central core similar to the towers.

911research.wtc7.net...

Building 7 was a 100% steel frame building. Like most modern skyscrapers, it had a series of columns ringing its perimeter, and a bundle of columns in its core structure. Its perimeter columns numbered 58 and its core columns numbered 25

It would most definitely not fail at temps as low as 250C in 1 hour,

heiwaco.tripod.com...

These effects of heating are further documented by the recent fire tests of Zeng et al.
(2003), which showed that structural steel columns under a sustained load of 50% to 70% of
their cold strength collapse when heated to 250C.
Although a detailed computer analysis of columns stresses after aircraft impact is certainly
possible, it would be quite tedious and demanding, and has not been carried out by NIST.
Nevertheless, it can easily be explained that the stress in some surviving columns most likely
exceeded 88% of their cold strength 0. In that case, any steel temperature  150C sufficed to
trigger the viscoplastic buckling of columns (Baˇzant and Le 2008). This conclusion is further
supported by simple calculations showing that if, for instance, the column load is raised at
temperature 250C from 0.3Pt to 0.9Pt (where Pt = failure load = tangent modulus load), the
critical time of creep buckling (Baˇzant and Cedolin 2003, chapters 8 and 9) gets shortened
from 2400 hours to 1 hour (note that, in structural mechanics, the term ‘creep buckling’ or
‘viscoplastic buckling’ represents any time-dependent buckling; on the other hand, in materials
science, the term ‘creep’ is reserved for the time-dependent deformation at stresses < 0.50,
while the time-dependent deformation at stresses near 0 is called the ‘flow’; Frost and Ashby
1982).

The relatively small, isolated pockets of fire in 7

So all the guys from the FDNY that reported the characterized 7 as having large uncontrolled fires are liars?

How does a top third third which is weaker (weaker because the top part of the structure is designed to support less weight that the bottom part of the structure as it has less floors above to support) than the bottom third (or at the worst I'll give you same strength) pulverize the bottom (two) third without itself being pulverized at an equal or similar rate?

heiwaco.tripod.com...

The fact that the crush-up of entire stories cannot occur simultaneously with the crush-down
is demonstrated by the condition of dynamic equilibrium of compacted layer B, along with an
estimate of the inertia force of this layer due to vertical deceleration or acceleration...

It is
found that, immediately after the first critical story collapses, crush fronts will propagate both
downwards and upwards. However, the crush-up front will advance into the overlying story
only by about 1% of its original height h and then stop. Consequently, the effect of the initial
two-way crush is imperceptible and the hypothesis that the crush-down and crush-up cannot
occur simultaneously is almost exact.

[edit on 13-7-2010 by Joey Canoli]

reply to post by Joey Canoli

Building 7 was a 100% steel frame building. Like most modern skyscrapers, it had a series of columns ringing its perimeter, and a bundle of columns in its core structure. Its perimeter columns numbered 58 and its core columns numbered 25

Yes I know, this is what I was saying. It has 25 interior columns throughout, not just around the elevator shaft as in the towers, but now it is just arguing semantics.

It is true what other members continuously say about you, you take statements out of context because it is the only way you have a point to argue. Why did you quote me as saying

It would most definitely not fail at temps as low as 250C in 1 hour,

missing out the most important point of the sentence? This is what I said:

It would most definitely not fail at temps as low as 250C in 1 hour, especially as the structural members were all fire-proofed with a 2 hour minimum rating for stability and integrity.

You then completely failed to mention fireproofing at all in your explanation, the whole point of my statement.

Here's another of my statements taken out of context in-order to give you an arguing point:

The relatively small, isolated pockets of fire in 7

When what I actually said was:

The relatively small, isolated pockets of fire in 7 were not even comparable to the raging infernos survived by numerous other steel structures in history.

Do you know what relative means (not your cuzzies)? It is possible for something to be called both big and small, depending on what it is being compared with. When compared with the raging infernos that filled every fire cell and burned for over 24 hours in other structures in history, relative to those they were small and isolated. They were all contained within the fire cell in which they started.

The explanation as to

How does a top third third which is weaker (weaker because the top part of the structure is designed to support less weight that the bottom part of the structure as it has less floors above to support) than the bottom third (or at the worst I'll give you same strength) pulverize the bottom (two) third without itself being pulverized at an equal or similar rate?

given was a load of rubbish (yes I'm aware you provided a link to a fancy journal article).

However, the crush-up front will advance into the overlying story
only by about 1% of its original height h and then stop.

Any calculations of proof as to how this 1% was obtained?

Let's say one of the towers was put on its side and cut in half. One half was then rammed into the other half which was securely held in place at its end. You're saying that in the half doing the ramming, it would crush up only about 1% of h while proceeding to entirely crush the other half of the tower?

So you're also trying to tell us that the top third of the tower remained almost structurally intact until it had finished crushing the bottom half, then it crushed itself into the ground? In no videos of photographs can I see this top third riding a wave of destruction to the ground. Not even the official story will attempt to make claims this bold. They know when they can't explain something so they merely say total collapse ensued.

the hypothesis that the crush-down and crush-up cannot
occur simultaneously is almost exact.

This hypothesis is almost exact? I would love to see the experiment or computer model that proved this hypothesis. Oh wait, there is none.


I would also like to point out that the supposedly credible Mr Canoli supported comments and values produced by iamcpc but then failed to acknowledge or point out the vast array of errors in iamcpc's train-wreck of a calculation. Anything to stay patriotic to the OS right


[edit on 13-7-2010 by Azp420]

Originally posted by Azp420

Yes I know, this is what I was saying. It has 25 interior columns throughout, not just around the elevator shaft as in the towers, but now it is just arguing semantics.

Yes. I agree, you're argueing semantics cuz you're wrong. 7 had a core column/ext column arrangement. A search for "core" gives 64 hits in just chapters 1-8.

And just because it's not EXACTLY like the towers, you feel it gives you license to make your semantics arguement. So go ahead, disagree with Hoffman's site. And NIST.

You then completely failed to mention fireproofing at all in your explanation, the whole point of my statement.

Does steel fail at 250C, given the right load and time? This is NOT a semantics arguement, but a test to see if you agree with the proven engineering or not. Please be aware that this argument applies to the towers, where it is reasonable to presume that fireproofing was removed.

Heat transfer through fireproofing is another matter. If you wish to challenge NIST's estimate of what the steel temps were in 7, be my guest.

It is possible for something to be called both big and small, depending on what it is being compared with.

If you actually did that, you'd find that, for example, the Madrid building was about the same size as 7's core area. Rendering your opinion useless.

The explanation given was a load of rubbish (yes I'm aware you provided a link to a fancy journal article).

Translation: you have zero engineering papers that can dispute Bazant, and so you dismiss it out of hand as "rubbish".

Any calculations of proof as to how this 1% was obtained?

Yes.

Read the paper.

Let's say one of the towers was put on its side and cut in half. One half was then rammed into the other half which was securely held in place at its end. You're saying that in the half doing the ramming, it would crush up only about 1% of h while proceeding to entirely crush the other half of the tower?

Nope. And since you've made this rookie mistake, you'll never understand why it fails as a valid comparison.

So you're also trying to tell us that the top third of the tower remained almost structurally intact until it had finished crushing the bottom half, then it crushed itself into the ground?

I spent a whole lot of time getting to understand Bazant's paper, and what he was talking about here. It involves a lot of physics and engineering.

You have provided your own personal brand of incredulity as a rebuttal.

I'll take published engineering over incredulity every time. Thx.

In no videos of photographs can I see this top third riding a wave of destruction to the ground.

That would be cuz of the dust. Duuuuh.

Not even the official story will attempt to make claims this bold. They know when they can't explain something so they merely say total collapse ensued.

IOW, they have more important things to do than to explain these elementary engineering principles to laymen. Bazant took care of that however.

This hypothesis is almost exact? I would love to see the experiment or computer model that proved this hypothesis. Oh wait, there is none.

There are equations and math provided instead in that link.

Feel free to provide more accurate ones.

Your incredulity means nothing.

I would also like to point out that the supposedly credible Mr Canoli supported comments and values produced by iamcpc but then failed to acknowledge or point out the vast array of errors in iamcpc's train-wreck of a calculation. Anything to stay patriotic to the OS right

Why would I care if he makes a mess of things?

I actually found it amusing that no one else could see the lunacy that he was proposing.

The fact that you are apparently the only one to see the errors in his calcs speaks LOADS about just how dumb your fellow truthers are.

reply to post by Joey Canoli

Does steel fail at 250C, given the right load and time?

Steel will fail at 20C (room temp) given the right load and time. That is kind of a pointless question.

If you actually did that, you'd find that, for example, the Madrid building was about the same size as 7's core area. Rendering your opinion useless.

Again you've quoted me out of context. I was referring to the size of the fires.

Nope. And since you've made this rookie mistake, you'll never understand why it fails as a valid comparison.

So gravity magically protects the top third from being crushed? Every action has an equal and opposite reaction. The strong axis of the top third fell symmetrically into the strong axis of the bottom third. At the point of impact almost equal forces (with the small difference due to self weight) would have to be survived by both thirds. You're telling me that self-weight made up a large proportion of the overall forces, I find that highly unlikely, especially as nobody can produce an experiment or computer model replicating this.

IOW, they have more important things to do than to explain these elementary engineering principles to laymen. Bazant took care of that however.

Wow. Now that is a bold statement. The OS left out the most critical part because they have more important things to do than explain it to laymen? What about us engineers that want an official explanation? What more important things did they need to get onto? Drafting up the Patriot Act or Afghanistan invasion plans?

This hypothesis is almost exact? I would love to see the experiment or computer model that proved this hypothesis. Oh wait, there is none.

There are equations and math provided instead in that link.

Usually in the practice of reputable science, theory cannot be used to prove a hypothesis, it is usually proved through experimentation. But feel free to subscribe to whatever brand of science you like.


[edit on 14-7-2010 by Azp420]

Originally posted by Azp420

Steel will fail at 20C (room temp) given the right load and time. That is kind of a pointless question.

So how about viscoplastic creep at 250C? Do you agree that steel that is within it's load range, will fail due to creep after an hour at high enough loads? Therefore rendering truther arguements that steel can't fail at 250C wrong?

Again you've quoted me out of context. I was referring to the size of the fires.

The context is that the FDNY considered them to be large fires. They were there. You were not. So who is right? Who is lying by calling them small fires?

So gravity magically protects the top third from being crushed?

Ahhhh. So you DO know why your previous question was a stupid one. At least now I see who I'm dealing with.

Every action has an equal and opposite reaction.

Yep, and these physics are explained, with the calculations offered, in the paper I linked you to. You were asking for calcs. there they are.

The strong axis of the top third fell symmetrically into the strong axis of the bottom third.

Are you advocating a direct and square axial impacts of the columns? Bazant uses this hypothetical and obviously impossible scenario to make the best case scenario for halting the collapse. It doesn't though.

In the real world, the top 1/3 falls mostly onto the floors, which are weaker. Gravity - you know, the force that you tried to ignore in your horizontal question - takes care of the rest.

At the point of impact almost equal forces (with the small difference due to self weight) would have to be survived by both thirds.

Only for an axial column impact. Otherwise, the upper 1/3 falls onto the floors.

You're telling me that self-weight made up a large proportion of the overall forces.

Self weight. Gravity. Conversion from PE to KE as the upper 1/3 moves. These are the forces at work.

I find that highly unlikely, especially as nobody can produce an experiment or computer model replicating this

Incredulity noted. Which I find especially strange after you asked for engineering calcs and have now ignored them.

Wow. Now that is a bold statement.

How so? The NIST report refers to the Bazant papers.

The OS left out the most critical part

Collapse initiation is the most critical part. They covered this.

because they have more important things to do than explain it to laymen?

Bazant covered it before NIST even got funded.

What about us engineers that want an official explanation?

About initiation? NIST covered it.

About propagayion? Bazant covered it, and NIST referred to it in their report. Therefore, it is obvious that they agreed with it and saw no reason to add to it.

What more important things did they need to get onto? Drafting up the Patriot Act or Afghanistan invasion plans?

Building 7.

Usually in the practice of reputable science, theory cannot be used to prove a hypothesis, it is usually proved through experimentation.

Buildings aren't designed through experimentation. They are designed using known properties of steel, concrete, 2x4's, etc. Therefore, a collapse hypothesis does not deal with radical unknowns. Stress/strain levels/load transfers/fire spread/etc can be figured out through modeling, since this is how they are designed in the first place.

But feel free to subscribe to whatever brand of science you like.

I definitely won't be ascribing to truther science.

I prefer the rational and sane world.

reply to post by Joey Canoli

Therefore rendering truther arguements that steel can't fail at 250C wrong?

I just said steel can fail at just 20C or whatever temperature. What exactly is your point?

The context is that the FDNY considered them to be large fires. They were there. You were not. So who is right? Who is lying by calling them small fires?

It's about relativity my friend, a concept it seems you are struggling to grasp. Stop quoting me out of context to give you an arguing point and re-read my previous posts.

Ahhhh. So you DO know why your previous question was a stupid one. At least now I see who I'm dealing with.

No, I was proving the point that gravity does not have some magical ability to protect the top third while the bottom third is crushed.

Yep, and these physics are explained, with the calculations offered, in the paper I linked you to. You were asking for calcs. there they are.

Anyone can come up with theoretical calculations to prove anything. Prove it with experimentation or a computer model at the very least.

By the way, I assume Bazant is going against the OS pancake theory?

Only for an axial column impact. Otherwise, the upper 1/3 falls onto the floors.

You realise the floors in the top third are undergoing almost identical forces to the floors in the bottom third in this scenario?

Collapse initiation is the most critical part. They covered this.

Most people people would find the spectacular fashion in which the towers collapsed pretty critical and a huge red flag. Why not have an OS for this?

About initiation? NIST covered it.

No, an official explanation as to what happened after initiation. Do you not read my posts at all? You seem to just quote me and make up the context. I've seen you do it with other members too.

Building 7.

Of-course, the biggest red flag of them all.

Buildings aren't designed through experimentation.

Ah, now I can see who I'm dealing with. You obviously have no experience in the industry and rely on linking Bazant's paper for everything you can't explain. I'm not going to sift through the whole paper trying to find the answer to my question that you cannot provide. Buildings are designed with experimentation. You cannot start from scratch and use theory to PROVE a structure will not fail. Much experimentation is done on steel members to find out its properties and the amount of variance between members. This experimentation is still ongoing! We still do not know all there is to know and coming up with theoretical formulas tells us nothing we can use in the real world. Every formula in my code is based on real world experimentation. Trying to come up with these formula without experimentation is ludicrous. In timber structures each member is tested with experimentation before it is committed. In masonry and concrete structures samples of the actual material used is extensively experimented on to ensure it is satisfactory. Scale models of bridges and high-rise buildings are put on shake tables to test their response in earthquakes. Highly architectural buildings also undergo experimentation in wind tunnels to determine the effects to the aerodynamics.

Theoretical equations prove nothing without experimentation to back them up. Welcome to the real world.

[edit on 15-7-2010 by Azp420]

Originally posted by Azp420

I just said steel can fail at just 20C or whatever temperature. What exactly is your point?

Ok then, you agree that truthers are liars when they say that the core steel ib the towers only reached 250C, and that is not enough to make them fail, since you agree that viscoplastic creep at those temps is proven engineering science.

It's about relativity my friend,

I agree. The FDNY considering the fires in 7 to be "large" is more relative to the discussion than what your opinion is, since they were there, and you were not.

Making truthers liars when they characterize the fires as "small".

No, I was proving the point that gravity does not have some magical ability to protect the top third while the bottom third is crushed.

It's not magic. It's the science of physics.

And what exactly have you proven again? That you use irrelevant comparisons? That after asking for the calcs on this crush down explanation, you will avoid giving any critique on them at all, and continue with your incredulity as the sole reason for being a truther, since to acknowledge the calcs you asked for would spoil the little world of cognitive dissonance you have built for yourselg?

I agree.......

Anyone can come up with theoretical calculations to prove anything. Prove it with experimentation or a computer model at the very least.

Explain to us all what makes these calcs "theoretical" when he takes accepted structural engineering science and physics and writes them down for all to examine?

This is how buildings are designed. Are you calling the effort put into these designs "theoretical" also then, and of zero real value?

That'll be a surprise to structural engineers. Their work is without merit, according to you....

By the way, I assume Bazant is going against the OS pancake theory?

What pancake theory would that be? The "OS" doesn't involve a pancake initiation, it was ruled out by NIST. FEMA proposed that as a possibility.

Bazant agrees with NIST that a pancake initiation did not occur.

You realise the floors in the top third are undergoing almost identical forces to the floors in the bottom third in this scenario?

At the moment of impact, this is correct. What happens though after the floors are destroyed? Both of them are accelerated by gravity and fall onto the next floor below.

You still don't understand gravity. You are only viewing the problem through your horizontal collision colored glasses.

Most people people would find the spectacular fashion in which the towers collapsed pretty critical and a huge red flag. Why not have an OS for this?

And most people realize that without initiation, there is no collapse progression, making initiation the most important factor for structural engineers to avoid.

No, an official explanation as to what happened after initiation.

I told you already. NIST referred to Bazant's work and didn't see any point on expanding on it.

Do you not read my posts at all?

You should be asking yourself that question.

Of-course, the biggest red flag of them all.

How so?

Do you have a structural engineering report that refutes anything in it?

Or just more incredulity?

I'm not going to sift through the whole paper trying to find the answer to my question

Why not?

Would it make it more readable if I was to reproduce it here in my own words? His papers contain all the structural and physics calcs that you are asking for, but it is difficult to reproduce it here in this forum.

If you want to avoid confronting the accepted engineering and physics calcs that you demanded, that is your choice.

Buildings are designed with experimentation.

No. They use accepted design facts and city/county/state/fed codes.

Here's one such guideline.

www.aisc.org...

You cannot start from scratch and use theory to PROVE a structure will not fail.

I agree. Which is why they don't use theoretical anything to design buildings. They use accepted engineering facts and calcs to ensure that the buildings they design are safe.

Much experimentation is done on steel members to find out its properties and the amount of variance between members.

i agree. However, these are used to refine their knowledge base, not to actually design buildings.

Every formula in my code is based on real world experimentation. Trying to come up with these formula without experimentation is ludicrous.

Ok, I see your point.

You're wrong though to say that buildings are designed through experimentation. They are designed by using the codes, which are based on accepted structural engineering, which is refined through experimentation.

You're short cutting that 3 step process in order to complain about some perceived lack of data, namely physical reproduction of the events. This is of course dishonest.

In masonry and concrete structures samples of the actual material used is extensively experimented on to ensure it is satisfactory.

This is called quality assurance. Not experimentation.

Scale models of bridges and high-rise buildings are put on shake tables to test their response in earthquakes. Highly architectural buildings also undergo experimentation in wind tunnels to determine the effects to the aerodynamics.

I CAN agree to this. The towers were in fact subjected to wind tunnel tests, satisfying your point. Even though there is a provision in the NYC building code that makes this unnecessary.

Theoretical equations prove nothing without experimentation to back them up. Welcome to the real world.

And since I've proven you to be dishonest as to where the experimentation alters the way in how buildings are actually designed, everyone can see that you're tilting at windmills.

Namely - you're lying about the role of experimentation takes in order to avoid the equations that Bazant gives.

This is a fine example of cognitive dissonance.

[edit on 16-7-2010 by Joey Canoli]

Originally posted by Joey Canoli
Ok then, you agree that truthers are liars when they say that the core steel ib the towers only reached 250C, and that is not enough to make them fail, since you agree that viscoplastic creep at those temps is proven engineering science.

I didn't say that, I said steel can fail at 20C.

I agree. The FDNY considering the fires in 7 to be "large" is more relative to the discussion than what your opinion is, since they were there, and you were not.

Again, you seem to just be making up the context to fit whatever point you are trying to make. Regardless of what adjective some fire fighters used, the fires in WTC7 were no way comparable in size with some of the raging infernos survived by other high-rise steel structures in history.

Making truthers liars when they characterize the fires as "small".

It's all relative, but I know you like to argue semantics.

Explain to us all what makes these calcs "theoretical" when he takes accepted structural engineering science and physics and writes them down for all to examine?

Allow me to quote from the link to the equations provided. Bazant does not seem to be under the same illusions you are.

Coefficient (gamma) (which is generally < 1 but not