1200 Architects And Engineers

Originally posted by ANOK
If you can not figure out why from those two pics then you have no experience with mechanics and should not be supporting the OS that you fail to understand.

ANOK. I've spotted you in a couple of threads now discussing 'experience with mechanics' and disqualifying your opponents based on your interpretation of their experience.

Please tell us what your experience is, and what your education/experience criteria are for 'official story' supporters.

reply to post by exponent

Yeah this is my mistake, I should have mentioned it more explicitly. Momentum is not a force, but the momentum of an object does lead to certain forces having to be overcome. In my excuse it was some horrible time in the morning.

Fair enough. I agree that the falling top section acquired a large amount of momentum, but if the top section impacts something that momentum only exerts a force if the top section is decelerated.

However, in reality we both know that it did not and tilted significantly. In this situation, the mass per floor to be accelerated is still the same, and so while the impact floors might cause a minor lowering of required force, the momentum transfer is still identical.

As the momentum transfer is still identical an equal amount of velocity should still be lost at each floor to conserve momentum. Roughly the same amount of force/energy should be required to crush/pulverize the concrete. I would also argue that roughly the same amount of overall force is required to overload each structural element. If less force was required on the side that was tilted down then it would have continued to lean over until the center of gravity was overhanging the edge of the building. One of the towers also had minimal lean.

Well again this is very hypothetical, we know that this did not occur in real life, and if the most conservative estimates (allowing for direct column-column impact for example) still causes building failure, then we have to assume that a less optimistic analysis also results in collapse.

I have no problem with collapse, I have a problem with the rate of collapse. We know that in the undamaged structure a huge amount of force must have been applied to destroy most of the structural elements, yet the top section continued to accelerate at the same rate it did through the heavily damaged initiation zone, indicating it was doing no more work to destroy the undamaged structure than it was to destroy the initiation zone. We know something destroyed the columns because it wasn't until the bottom that we had a spire sticking out above collapsed floors (which interestingly did not fail due to bending over a large unrestrained length).

This is also not true, the total distance over which WTC7 achieved free fall was 8 floors, and the collapse mechanism is not symmetrical, nor was the damage it sustained.

I would call 8 floors pretty sustained in terms of a structure fee falling. That's 8 levels worth of structural members that effectively ceased to exist. I'm not buying that every single column became unrestrained for 8 levels at the same time. After the 8 floors accelerations still remained close to free fall. The structure crushed itself with less force than it's self weight.

I know the OS says the internal structure was failing asymmetrically, but from what we could see:



The overall collapse can't get much more symmetrical than that.

Even though we disagree Azp. At least you are actually thinking about this from a technical perspective. I appreciate that and will try and point you to whatever sources I think are relevant.

Cheers. It's refreshing to have an intelligent debate with someone on a technical perspective.

Originally posted by exponent
Please tell us what your experience is, and what your education/experience criteria are for 'official story' supporters.

I've been involved in mechanics and engineering all my life. I'm a certified mechanical drafter, jet engine mechanic, diesel mechanic. I've learned enough over the years to understand how mechanical structures work, how basic physics work and how to apply it in context.

I can tell when someone has had an engineering background simply from how they talk about it. It's not hard mate.

BTW when are you going to actually address my point about the WTC 7 outer walls being on top of the collapsed building, and stop making this personal trying to find ways to discredit my claims. It doesn't take a rocket scientist to see what you're doing.

So what makes you such an expert on building collapses? How come you're not making millions collapsing buildings into their footprint using random fire and damage?

reply to post by ANOK


ANOK, why did the steel only supported sections of the Windsor Tower collapse from fire alone within 2 hours of being engulfed? Why is that ANOK? And dont bring up how the whole thing didnt collapse because that is irrelevant, due to the big honking steel reinforced/concrete core that remained standing. My beef is with the obvious steel only section failing with only fire to blame. Explain why the steel managed to fail with fire alone. Dont go off on it surviving. The steel failed, so why did it happen? Here is a link that will give you all the info you need, so YOU need to explain to me why and how the steel managed to fail from fire alone:

Windsor Tower Fire

What happened to the steel?

I just posted your thread on my face book.

Originally posted by Azp420
Fair enough. I agree that the falling top section acquired a large amount of momentum, but if the top section impacts something that momentum only exerts a force if the top section is decelerated.

Sure, but deceleration is a result of any impact, so that force is exerted in all impacts. It's even more annoying than that if we deal with energy because we have to estimate how much energy was expended in destruction too. This has been done in the Bazant series of papers though.

As the momentum transfer is still identical an equal amount of velocity should still be lost at each floor to conserve momentum. Roughly the same amount of force/energy should be required to crush/pulverize the concrete. I would also argue that roughly the same amount of overall force is required to overload each structural element. If less force was required on the side that was tilted down then it would have continued to lean over until the center of gravity was overhanging the edge of the building. One of the towers also had minimal lean.

Not disagreeing here, but the next paragraph seems to contradict your view on this?

I have no problem with collapse, I have a problem with the rate of collapse. We know that in the undamaged structure a huge amount of force must have been applied to destroy most of the structural elements, yet the top section continued to accelerate at the same rate it did through the heavily damaged initiation zone, indicating it was doing no more work to destroy the undamaged structure than it was to destroy the initiation zone.

In the previous paragraph, you agree that the momentum transfer is identical, and this is what determines the collapse rate primarily, as even if the lower sections provide significantly more force, if the energy required to decelerate the object is significant, the results become relatively insensitive to the force applied.

Plus, lets face it, the measurements of descent acceleration are not hugely accurate as they are based off video records which are several metres per pixel. Deceleration by a fraction of this would simply not be detectable in the data we have.

We know something destroyed the columns because it wasn't until the bottom that we had a spire sticking out above collapsed floors (which interestingly did not fail due to bending over a large unrestrained length).

Well those columns previous held 50% of the mass of the towers, so it's not hugely surprising they didn't fail in compression. They did actually fail at the bottom, but we don't know whether this was due to moment or shear or what exactly.

I would call 8 floors pretty sustained in terms of a structure fee falling. That's 8 levels worth of structural members that effectively ceased to exist. I'm not buying that every single column became unrestrained for 8 levels at the same time.

That's definitely not what happened, the internal structure was destroyed horizontally across the building, until it could not hold up its own self weight. At this point failure is extremely rapid and will be progressive. An analogy I've used before is taking a weight, tying it to a hook with three strings under equal tension, where the load is 80% of the maximum load of all three strings. If you were to then cut one string, the other two would fail almost instantaneously. This is the mechanism behind progressive collapse.

After the 8 floors accelerations still remained close to free fall. The structure crushed itself with less force than it's self weight.

Aha! I think I have figured where you are getting this idea from. This was a video produced by david chandler I believe? Who said that if the force was less than the static force, then it must be suspicious. However, the equations he uses to determine this only equal static force in one condition: the building doesn't collapse. Using his logic, any collapse is suspicious, because the resultant force calculations taking into account only acceleration over a large period result in less force than the self weight. It's a misleading analysis, and hopefully you can appreciate that's why momentum transfer is important.

I know the OS says the internal structure was failing asymmetrically, but from what we could see:
...
The overall collapse can't get much more symmetrical than that.

There are three noticable things about this gif:
1. It ignores the collapse of the east penthouse, which occured 6 seconds before this begins. This was asymmetric, caused by the failure of a single column, and is what caused the damage that resulted in the collapse
2. The central penthouse began to collapse before the western penthouse, and before the exterior of the building.
3. The period at which it reached free fall occurs a couple of seconds after the global initiation. If this was caused by explosives taking out all of the columns, what structural element resisted the collapse for so long?

Cheers. It's refreshing to have an intelligent debate with someone on a technical perspective.

Indeed, I look forward to continuing it.

Originally posted by ANOK
I've been involved in mechanics and engineering all my life. I'm a certified mechanical drafter, jet engine mechanic, diesel mechanic. I've learned enough over the years to understand how mechanical structures work, how basic physics work and how to apply it in context.

Ok, that's a respectable profession, but some of your statements seem to be at odds with this experience.

I can tell when someone has had an engineering background simply from how they talk about it. It's not hard mate.

That's true enough, but you shouldn't be trying to judge people on how they talk about things. Lots of topics differ even across the pond.

BTW when are you going to actually address my point about the WTC 7 outer walls being on top of the collapsed building, and stop making this personal trying to find ways to discredit my claims. It doesn't take a rocket scientist to see what you're doing.

I'm not trying to discredit your points, I just don't think what you're saying happened did. I don't see any evidence that all four walls are on top of WTC7, and we know for a fact that it did not collapse purely into its footprint. There is even video showing it tilting towards the south in the final collapse stages.

What makes you think that all four walls are on top of the debris pile? Can you identify any particular bits that can only be from the south wall?

Originally posted by GenRadek
ANOK, why did the steel only supported sections of the Windsor Tower collapse from fire alone within 2 hours of being engulfed?

Even if what you say is taken at face value, it still doesn't compare to the WTC Towers. If you think it does, please show pictures of what these steel supports looked like before they collapsed, and then show the perimeter columns from the WTC Towers. Then show us the amount of fire that engulfed those supports in Madrid, and the amount of fire that engulfed them in Manhattan.

If you want to make an honest comparison, let's see you do this.

Originally posted by bsbray11
please show pictures of what these steel supports looked like before they collapsed, and then show the perimeter columns from the WTC Towers. Then show us the amount of fire that engulfed those supports in Madrid, and the amount of fire that engulfed them in Manhattan.

If you want to make an honest comparison, let's see you do this.

I find it funny that you talk about an honest comparison, then ask for pictures. Why, it's as if you know that the pictures would superficially support your case!

It's quite obvious what you're doing, but the fact of the matter is that these steel supports were severely affected by the heat, and their failure is not the same mechanism as with the world trade centre. If you were actually looking for accurate analysis, you would be asking how quickly they were heated, and what fireproofing was used.

Please bsbray, don't waste your time on here by acting as if popularity dictates truth, the fact of the matter is that buildings have only survived large fires due to three factors
1. Intact fireproofing
2. Concrete reinforcement
3. Active firefighting

It's unlikely you can find a single example where an occupied building was fully involved with fire as the WTCs were where it survived without one of those three factors. Ignoring these factors and asking for simple comparison pictures does not mean they do not exist.

Originally posted by exponent
I find it funny that you talk about an honest comparison, then ask for pictures. Why, it's as if you know that the pictures would superficially support your case!

Are you seriously complaining because I'm asking him to show us what he's talking about?

Cry about it why don't you.

It's quite obvious what you're doing

I would hope so.

but the fact of the matter is that these steel supports were severely affected by the heat

And the other facts of the matter are that the steel sections in question were much, much smaller than the WTC members, and were subjected to a much worse fire. The size of the cross-section is directly related to the amount of heat required, and as someone with common sense might imagine, more steel means more heat is required to heat to a given temperature.


So you're going to make a comparison to another building, but then refuse to actually show the comparison. It's funny that showing the actual pictures is a "superficial" comparison to you, but empty words based on nothing aren't I guess.

I'll do it for you.




That is the steel that failed at the Windsor Tower, and this is the fire that caused it to fail:





Which you are trying to compare, to these columns:




And this fire:





This is what you are comparing. It shouldn't take a genius to see the blaring differences. I'm not even going to point them out because they're so damned obvious I shouldn't need to.

Yes, I used actual pictures. Oh nooo, what an awful crime, I exposed your garbage for what it is. Why do people have to take these damned biased truther pictures??

So you're going to make a comparison to another building, but then refuse to actually show the comparison. It's funny that showing the actual pictures is a "superficial" comparison to you, but empty words based on nothing aren't I guess.

I'll do it for you.

What a surprise, you not only ignore the fact that it is a superficial comparison, but post the most dramatic pics of one, and presumably the least dramatic pics you could find of the other.

Did you miss out these pictures?

Originally posted by exponent
What a surprise, you not only ignore the fact that it is a superficial comparison, but post the most dramatic pics of one, and presumably the least dramatic pics you could find of the other.

Hello?

Do you think the WTC Tower fires were even CLOSE to the Windsor Tower fires? Do you think the column cross-sections are equal?

Go ahead and say "yes" and make yourself look that much more foolish.

Remember anyone who can read these posts in the first place must have eyes.




We'll compare your own photos now:



The first worst pic of the WTC fires you could find, apparently:




Windsor Tower (now I am trying to find the most dramatic I can, thank you very much):




The second worst pic of the WTC fires you could find:




Windsor Tower again:





Gee whiz, let's keep trading pics like this.


Maybe you'll magically start showing that the WTC fires were worse.


Or you want to compare the column sizes again?


Maybe you'll magically be able to demonstrate that the Windsor Tower had even bigger columns than the WTC Towers, even though to everyone else on planet Earth they obviously didn't.

Double post.

Originally posted by bsbray11
Do you think the WTC Tower fires were even CLOSE to the Windsor Tower fires? Do you think the column cross-sections are equal?

This doesn't support what you think. When you quote a picture of the WTCs external wall deforming, and then try and play 'one up' image tag, it's quite sad.

How do you not understand that image comparisons are superficial, that's why I posted them. Trying to post worse looking ones in response is almost an admission you're not looking at actual analysis. If you were truly interested in the facts of the day, you would know that there are no good comparisons to the towers, and in fact as usual I have already explained this to you.

Originally posted by exponent

Originally posted by bsbray11
Do you think the WTC Tower fires were even CLOSE to the Windsor Tower fires? Do you think the column cross-sections are equal?

This doesn't support what you think. When you quote a picture of the WTCs external wall deforming, and then try and play 'one up' image tag, it's quite sad.

I guess it just requires a special level of education to realize the WTC Towers were in a much more dire situation from their much less intense fires and larger columns, than the Windsor Tower with its much more intense fires and much smaller columns. You got me there.

How do you not understand that image comparisons are superficial, that's why I posted them.

Then what isn't superficial? Lying and saying the WTC fires were worse?

Originally posted by bsbray11
I guess it just requires a special level of education to realize the WTC Towers were in a much more dire situation from their much less intense fires and larger columns, than the Windsor Tower with its much more intense fires and much smaller columns. You got me there.

It doesn't take a special education, it just takes an honest look at how building fires work, the construction of the two buildings, and the failure modes of both buildings.

I'm not lying to you, I'm not distorting anything. The reality of the matter is that the WTC towers were much more vulnerable to fire than the Windsor Tower. Primarily because it was made out of reinforced concrete other than the steel sections. They all failed entirely, the reinforced concrete sagged and spalled, but did not collapse as it is extremely fire resistant.

The same cannot be said for the floors of the WTC. None of this is lies, you can look it up and test it yourself, but I won't be bothering to respond to any more "nuh uh i'm right" type posts. Either look at the evidence available to you, or don't bother telling me that it's as simple as looking at pictures.

Originally posted by exponent

Originally posted by bsbray11
I guess it just requires a special level of education to realize the WTC Towers were in a much more dire situation from their much less intense fires and larger columns, than the Windsor Tower with its much more intense fires and much smaller columns. You got me there.

It doesn't take a special education, it just takes an honest look at how building fires work, the construction of the two buildings, and the failure modes of both buildings.

You have yet to actually discuss any of those things in detail. Hardly an "honest look" by not looking at all. In fact I think that is called "denial."

I'm not lying to you, I'm not distorting anything.

You're trying to insinuate that the Windsor Towers collapsed from comparable fires and had a comparable structure.

I showed you exactly how comparable the structure itself and fires were above. Now you are vaguely ranting about other nonsense that you have yet to bring into discussion.

If you have something else to add that suddenly makes the Windsor Tower more relevant to your argument then I'm all ears. So far all I've seen is that it had worse fires and smaller cross-sections of steel and still wasn't completely leveled to the ground. It's sad that this is the best you can do.

The reality of the matter is that the WTC towers were much more vulnerable to fire than the Windsor Tower.

Given that the WTC towers used many more and much larger columns, and suffered less intense fire, this statement is pure malarkey. Would like to see the "technical data" you apparently think you are basing this on.

Primarily because it was made out of reinforced concrete other than the steel sections. They all failed entirely, the reinforced concrete sagged and spalled, but did not collapse as it is extremely fire resistant.

Now you are lying again. All of the steel in the Windsor Tower did NOT fail. You must be looking at the wrong building.

The same cannot be said for the floors of the WTC

You can't say that all the steel in the WTC failed? Wow, another gem.

reply to post by bsbray11


OK, enough of this. I have reached my limit. You're not even bothering to look at my posts in more than a passing capacity. The Windsor Tower had a core and transfer structure of reinforced concrete, coupled with protected steel columns below floor #17. I explained how you couldn't find comparisons without these features in a previous post, and now you don't seem to understand that the unprotected steel failed entirely.

Hell, the very site you used earlier (I presume, I recognise the picture from my hometown's university) details it all for you:
www.mace.manchester.ac.uk...

I have no interest in repeating myself endlessly as I've said before. If you want to ignore the construction of the towers and ignore the construction of the Windsor Tower that's up to you. The fact of the matter is that the steel that became unprotected in the WTC was responsible for its failure, and the unprotected steel in the Windsor Tower failed entirely. The remaining steel was also damaged, but not to the same extent.

reply to post by bsbray11




Oh bsbray, and here I thought you'd be better than that!

Did you forget those lovely little floor trusses? You remember those right? The ones that helped initiate the collapse by sagging, pulling in the exterior columns prior to the global failure? Yeah those trusses. The very light steel trusses that are very susceptable to fires when fireproofing is dislodged.


See the little guy sticking out there supporting the floor? Yeah did you forget about them?



Well seeing as how the exterior columns were pulled in by them, I thought it would have been obvious that light steel trusses were just as susceptable as the steel beams exposed to the fires in the Windsor. So care to try again? Lets see, Windsor tower's steel failed within 2 hours of exposure. Light steel trusses on the WTC failed in a little less time. Also, I'd read up on just how dangerous light steel truss constructions are in fires. I'd start with the fire dept reports on them. Then get back to us when you are all caught up.

Originally posted by exponent
OK, enough of this. I have reached my limit. You're not even bothering to look at my posts in more than a passing capacity.

No, I understand completely what you are posting and I am responding to it. It's you that keep repeating exactly what I am showing you is wrong. If you've had your limit of this it's understandable because cognitive dissonance is a very real phenomenon. You realize I am not being emotionally affected by this, I can keep this up all night, because it takes no energy to post basic facts over and over and just let you deal with them. It's easy for me.

Fact: The WTC Tower had more columns, and larger columns, than the Windsor Tower.

Fact: The WTC Tower suffered less intense fires by any sensible viewing than the Windsor Tower.

Fact: Despite what you claim, the Windsor Tower's steel did NOT all fail.

Fact: The only steel that DID fail in the Windsor Tower were the much thinner columns, that experienced much more intense fire.

You can keep arguing with these facts, it's fine with me.

Like I said, for me to keep posting them takes little/no energy from me because I know they are accurate and I have no problem accepting them either. But when you DO think they're inaccurate and DO have a problem with them, I can see how frustrating it would be to try to argue with them.

The Windsor Tower had a core and transfer structure of reinforced concrete, coupled with protected steel columns below floor #17.

Maybe you are unaware but the WTC Tower had massive steel box columns for a core structure and NO ONE is saying they failed from the fires destroying them.

I explained how you couldn't find comparisons without these features in a previous post, and now you don't seem to understand that the unprotected steel failed entirely.

Let's see, you think the fact that the steel was unprotected has something to do with it, but the intensity of the fires and relative sizes of the columns have nothing to do with it, apparently.

If you want to ignore the construction of the towers and ignore the construction of the Windsor Tower that's up to you.

Originally you were arguing that they WERE a valid comparison.

Now you're saying they're NOT a valid comparison because of the core structures differing.

Consider this proof that your argument has been defeated. You are now arguing AGAINST their comparison while earlier you were arguing FOR their comparison. This is hilarious.