What are the most glaring flaws in the Popular Mechanics "debunking" of 9/11?

Originally posted by GenRadek
Yes they do. The trusses are what gave the whole building the support it needed to stand.

That is NOT true. The trusses held the floors up, NOT the whole building. The core is what gave the building its stability and is what held up the floors, along whit the outer mesh, you have it backwards. Trusses failing would not cause the core to fail, period.

If this was true the trusses would not be able to withstand the building swaying in the wind lol. This is why the much bigger box columns of the central core was the main weight bearing structure. If you knew anything about engineering, or physics, you would just need to look at the building to understand this.

Geeze ANOK after all this time you still dont get the design features of the WTCs?

LOL listen to Mr.Expert who thinks floors trusses hold up a sky scraper. Yes Geeze indeed. How many time have we had a discussion Gen that I haven't shown you to be completely wrong? I believe that would not none.

Oh so light steel trusses wont fail until maybe after an hour of being exposed?

Go on to some firefighter websites and fire safety sites and books and then do some actual research on just how fast light steel trusses can fail from fire alone (not including a whole 767 impacting them first.) Again, its been stated, time and again of just how trusses behave in fires, its a shame you still dont get it. And then you expect us to believe you when you talk abotu physics?

Oh, and also, why did McCormick Place's roof collapse in 20 minutes of fire when they had huge heavy steel trusses supporting the roof???

You keep going on about 'lightweight' trusses, lightweight is just a word, what are you comparing them to? Lightweight doesn't mean they were not strong enough to do their job. I KNOW how STEEL acts in fire, trusses are made from steel. You are just playing semantics as usual.

Oh so a sagging truss will not put any extra force on the objects it is attached to?

NO they won't. You do know what sagging means right? It means the steel is malleable and can't hold it's own weigh so it sags, there are NO extra forces pulling on the columns, because it's now MALLEABLE and stretches. It's not a solid rigid beam anymore.

Well then golly gee, why are firefighters so afraid of going into buildings where the roofs are supported only by light steel trusses?

They must be stupid then!

Again, do some actual research into light steel trusses and fires. Its too bad those conspiracy sites like to keep that information away from you. I wonder why?

Because the roof might collapse? How does that prove the trusses can pull in columns they're attached to when they sag from heat?

So wait, you really still think that just one floor fell onto the floor below it when the WTCs started to collapse? ANOK, Earth to ANOK, its been 9 years. Try 30+ floors collapsing onto ONE floor below it. Let us see, 30 floors, moving as one mass, impacting one floor below it. Who is going to win?

Your physics is a little flawed there. 30 floors dropping on one floor will crush the one floor, and then allow the 30+1 floors to impact the next floor, and the next floor, and the next floor, in a growing chain reaction where momentum is increasing and the mass is increasing. Boy ANOK you sure did miss a lot in those physics classes! Better go back and catch up!

The first floor of the 30 floor block is still going to put the same force on the first floor it hits as does on itself (equal oposite reactions), if the impacted floors was destroyed, crushed, pulverized (which they were), then the impacting floor would also be severely damage, every floor impact would lose impacting floors, even if all the impacted floor were crushed and only half the impacting floors the collapse would still not be complete. Again you fail to understand Newtons 3rd law.

But regardless that is not what happened. Watch some darn collapse vids and you can clearly see the upper block losing floors before the bottom is even effected.

Originally posted by jimmyx
please show where... 1 OTHER SKYSCRAPER COLLAPSE, ANYWHERE IN THE WORLD, ANYTIME IN THE HISTORY OF BUILDING where a steel re-inforced concrete building feel striaght down in seconds due to fire.
you have none, the NIST has none....because it has never happened, period.

You're right. Because NONE of the WTC buildings were seel-reinforced concrete buildings. NONE!!

Originally posted by FDNY343

Originally posted by jimmyx
please show where... 1 OTHER SKYSCRAPER COLLAPSE, ANYWHERE IN THE WORLD, ANYTIME IN THE HISTORY OF BUILDING where a steel re-inforced concrete building feel striaght down in seconds due to fire.
you have none, the NIST has none....because it has never happened, period.

You're right. Because NONE of the WTC buildings were seel-reinforced concrete buildings. NONE!!

More drama, evasion and nit-picking.

I'm still holding my breath for you to show us all how much smarter you are than Newton.

So far you've provided no proof of your claim that an aluminum wing can cut my wood stove in half, not to mention all that massive steel we saw on the TeeVee.

No proof...NONE!

reply to post by ANOK

That is NOT true. The trusses held the floors up, NOT the whole building. The core is what gave the building its stability and is what held up the floors, along whit the outer mesh, you have it backwards. Trusses failing would not cause the core to fail, period.

So the exterior columns would freestand without the floors connecting them to the core, and the core would freestand without the floors supporting them to the exterior? The core would not have survived without the rest of the structure. If the floor trusses and the exterior columns failed, and went down in one motion, then how the heck is the core going to survive? Also, we did see the core survive. A good 60+ floors of it managed to survive, before it too collapsed. According to you, the core should have survived completely. Well, that is not the case. Each segment needed the other to survive.

LOL listen to Mr.Expert who thinks floors trusses hold up a sky scraper. Yes Geeze indeed. How many time have we had a discussion Gen that I haven't shown you to be completely wrong? I believe that would not none.

Whatever you have to tell yourself to make your self feel better there ANOK. So if we removed the floor trusses from the WTC, and left the core and exterior alone, it would still stand?

You keep going on about 'lightweight' trusses, lightweight is just a word, what are you comparing them to? Lightweight doesn't mean they were not strong enough to do their job. I KNOW how STEEL acts in fire, trusses are made from steel. You are just playing semantics as usual.

Yes, they are known as lightweight steel trusses. Do you know what a lightweight steel truss is? It is the most commonly used item in roof support for a variety of buildings. Also, thinner, lighter steel will react to fires far more rapidly than larger thicker steel. However, as McCormick Place has shown, even heavy steel trusses fail from fire alone rapidly. Also you never address the fact that firefighters usually do not enter buildings with steel trussed roofs like the type used in the WTC. Why is that ANOK? Its not semantics. Its life and death when it comes to trusses. The light steel trusses were strong enough to do their job, just they are prone to rapid failure IN FIRES. Do I need to direct you to a fire safety professional, or a fire fighter that has experience with this? Hell I can even direct you to the firefighter handbooks. But as usual, the real facts are just semantics. Boy oh boy, if that is not a genuine "hand waving away" of the facts, I dont know what is. And from your response, I can tell, you have NO idea how steel acts in fire. Especially if you cant understand the basic fact that light steel trusses fail in fires very rapidly. But you wont even acknowledge that. Do some actual research. I know I have, and I do know that you have no idea when it comes to steel trusses and fires.

NO they won't. You do know what sagging means right? It means the steel is malleable and can't hold it's own weigh so it sags, there are NO extra forces pulling on the columns, because it's now MALLEABLE and stretches. It's not a solid rigid beam anymore.

Oh so the fact that it is supporting an entire floor deck while malleable is not dangerous? How does steel react when it is softened and under load? Refresh my memory ANOK. Do you even know? You claim to know so much about steel. How did you forget that?

Because the roof might collapse? How does that prove the trusses can pull in columns they're attached to when they sag from heat?

So then why were those exterior columns all bending inward prior to collapse? Magic thermite? Magic bombs?

The first floor of the 30 floor block is still going to put the same force on the first floor it hits as does on itself (equal oposite reactions), if the impacted floors was destroyed, crushed, pulverized (which they were), then the impacting floor would also be severely damage, every floor impact would lose impacting floors, even if all the impacted floor were crushed and only half the impacting floors the collapse would still not be complete. Again you fail to understand Newtons 3rd law.

Do you even know what you are saying? You yammer on and on about Newton's 3rd Law, and yet you dont even understand the mechanics of what was happening to the WTC. Are you saying that the floors impacting each other were elastic collisions? Is that why you harp on and on about Newtons 3rd Law? Well there is a whole host more to it than just that. Are you forgetting Conservation of momentum? What about inelastic collisions? The 30 floors impacting the lower floor as one unit was an INELASTIC collision. The top 30 floors impacted the floor below. Yes there was a reaction between the two. However, according to the laws of momentum, that didnt stop the collapse. It kept going, as in accordance with momentum. Also, it was an inelastic collision, the collapse continued.

Boy so many holes in your "physics" knowledge.

reply to post by GenRadek


I can't speak for Anok, but what I saw was like a fuse going off, not a pancaking, progressive collapse, and wouldn't the lower part of the building already be holding the weight of the upper floors anyway?

They were designed to hold the weight of a fully occupied building plus the impact of a fully loaded 707, plus the forces of nature, plus 50% or some sh!te.

Anok is right to say the failing floors would take as much as they were giving (it's the law), because the only increase in weight was the alleged plane, the lower you go on the building the thicker the steel and the stiffer the resistance. We all know how quickly the towers collapsed on the TeeVee, so what we saw on the TeeVee couldn't have been a collapse...according to Newton (sorry). It would have taken longer...and I doubt it would have gone any further than the impact zone had a real plane been involved (it wasn't), because below the impact zone was undamaged support already holding up the damaged section's weight. Makes no sense. Something else must explain it.

Originally posted by Yankee451
It would have taken longer...and I doubt it would have gone any further than the impact zone had a real plane been involved because below the impact zone was undamaged support already holding up the damaged section's weight. Makes no sense. Something else must explain it.

You have no understanding of physics, and obviously have never heard of kinetic energy.

Originally posted by GenRadek
The core would not have survived without the rest of the structure. If the floor trusses and the exterior columns failed, and went down in one motion, then how the heck is the core going to survive? Also, we did see the core survive. A good 60+ floors of it managed to survive, before it too collapsed. According to you, the core should have survived completely. Well, that is not the case. Each segment needed the other to survive.

I disagree, I think the core could have stood with no problems at all simply by looking at its design.

The failure of a few floors is not going to cause the whole core to fail. The core is the strongest part of the structure, like a back-bone. All the other floors bellow the collapse zone would still be 100% intact and offering the same resistance to collapse it had since it was constructed. For the whole thing to fail as NIST claims then something had to remove the resistance of the lower floors, otherwise according to Newton the top floors would be gone before the bottom floors and no more collapse.

Whatever you have to tell yourself to make your self feel better there ANOK. So if we removed the floor trusses from the WTC, and left the core and exterior alone, it would still stand?

Maybe, maybe not, but you are making a silly claim. How many floors were removed Gen?

Yes, they are known as lightweight steel trusses...

LOL people talk about me posting the same nonsense over and over. I already covered this in my last post to you. None of what you're saying proves anything. Lightweight in comparison to what???? You still seem to think lightweight means unable to do what they were designed for.

Firefighter being afraid of lightweight trusses DOES NOT mean they would cause the complete collapse of a 110 story building if they failed.

Lightweight or not they were steel, steel is a known entity, you can not claim it is going to act differently to all other steel because someone calls it lightweight.

Stupid argument.

Oh so the fact that it is supporting an entire floor deck while malleable is not dangerous? How does steel react when it is softened and under load? Refresh my memory ANOK. Do you even know? You claim to know so much about steel. How did you forget that?

Who said anything about dangerous? We're talking about sagging trusses being able to pull in none-sagging columns they were attached to.

Yes I do know how a sagging beam would act. It's sagging from heat, how is it putting any more force on the columns? If there was more force on the truss from sagging, it would just cause the truss to sag more, but there is no extra force.

It's NOT going to happen and you can not prove me wrong on this.

So then why were those exterior columns all bending inward prior to collapse? Magic thermite? Magic bombs?

They weren't, all you are seeing is the aluminium cladding bend inwards from the heat. There was a gap between the cladding and the steel.

The outer mesh was not bending inwards.

Do you even know what you are saying? You yammer on and on about Newton's 3rd Law, and yet you dont even understand the mechanics of what was happening to the WTC. Are you saying that the floors impacting each other were elastic collisions? Is that why you harp on and on about Newtons 3rd Law? Well there is a whole host more to it than just that. Are you forgetting Conservation of momentum? What about inelastic collisions? The 30 floors impacting the lower floor as one unit was an INELASTIC collision. The top 30 floors impacted the floor below. Yes there was a reaction between the two. However, according to the laws of momentum, that didnt stop the collapse. It kept going, as in accordance with momentum. Also, it was an inelastic collision, the collapse continued.

Sigh, Newtons laws stay the same regardless of what kind of collision it was. You have obviously read some stuff on teh net and misunderstood it mate. Laws of momentum LOL, NEWTON is the laws of momentum, and a very important law of momentum is EQUAL AND OPPOSITE REACTIONS, REGARDLESS of whether it was an elastic or non-elastic collision.

Boy so many holes in your "physics" knowledge.

And once again I prove who really has the holes in their knowledge.

Originally posted by dereks

Originally posted by Yankee451
It would have taken longer...and I doubt it would have gone any further than the impact zone had a real plane been involved because below the impact zone was undamaged support already holding up the damaged section's weight. Makes no sense. Something else must explain it.

You have no understanding of physics, and obviously have never heard of kinetic energy.

'splain it to me. Wait...is that you FDNY343? Are we going to go wandering down the KE and V trumps all regardless of M path again?

Originally posted by ANOK

I disagree, I think the core could have stood with no problems at all simply by looking at its design.

The failure of a few floors is not going to cause the whole core to fail. The core is the strongest part of the structure, like a back-bone. All the other floors bellow the collapse zone would still be 100% intact and offering the same resistance to collapse it had since it was constructed. For the whole thing to fail as NIST claims then something had to remove the resistance of the lower floors, otherwise according to Newton the top floors would be gone before the bottom floors and no more collapse.

Well it wasnt just a few floors that failed, but some core columns were severed in the impact. Also, when the top section began its descent, it too would cause additional damage to the core as the top is also a solid structure with its own top. Wouldnt that also cause damage to the core section? Nothing had to "remove the resistance" of the lower floors. Once the collapse started, that was it.

Maybe, maybe not, but you are making a silly claim. How many floors were removed Gen?

I never said they were removed. I asked you would the towers stand if you removed all of the floors in the building.

LOL people talk about me posting the same nonsense over and over. I already covered this in my last post to you. None of what you're saying proves anything. Lightweight in comparison to what???? You still seem to think lightweight means unable to do what they were designed for.

Firefighter being afraid of lightweight trusses DOES NOT mean they would cause the complete collapse of a 110 story building if they failed.

Lightweight or not they were steel, steel is a known entity, you can not claim it is going to act differently to all other steel because someone calls it lightweight.

Stupid argument.

Ah ok, so steel is steel and all steel behaves the same way regardless of size, shape, design, etc. A 1/4" steel beam will react the same was as a 1ft thick steel beams, because, hey, its steel! Good to know ANOK. So then I guess engineers shouldnt pay attention to such details as steel thicknesses, steel shapes, steel composition, or steel structure design because according to you, steel is steel and doesnt matter what size it is or how it is utilized, be it in a truss design, a column, an I-beam. According to you, each example is interchangeable because its steel, and a truss, as found in the floors of the WTC will be just as good as an I-beam in all situations, loads, fires, structures, because they are all steel. Hallelujah!

Who said anything about dangerous? We're talking about sagging trusses being able to pull in none-sagging columns they were attached to.

Yes I do know how a sagging beam would act. It's sagging from heat, how is it putting any more force on the columns? If there was more force on the truss from sagging, it would just cause the truss to sag more, but there is no extra force.

It's NOT going to happen and you can not prove me wrong on this.

Sagging from what? Heat and........ loads. Yes heat will cause a steel truss to deform, but add a load on it, and it will deform more rapidly, and readily than a truss without a load. I'm sure you have heard of this before? Also on the floors that were burning, what about the exterior columns that were also exposed to the heat from the fires? Arent they also going to deform?

They weren't, all you are seeing is the aluminium cladding bend inwards from the heat. There was a gap between the cladding and the steel.

The outer mesh was not bending inwards.

Wait, what? Where did you ever hear such a ridiculous assumption? How exactly was that caused by the cladding? This is the first time in all these years of 9/11 Truther nonsense, that I heard such a crazy comment. The outer was not bending? So then why do we see the exterior columns bend inward right at the moment the top started to tilt and collapse?
Exterior sag
There was plenty of evidence the floor trusses were sagging, pulling the exterior inwards. Its not the aluminum cladding! Wow!

Sigh, Newtons laws stay the same regardless of what kind of collision it was. You have obviously read some stuff on teh net and misunderstood it mate. Laws of momentum LOL, NEWTON is the laws of momentum, and a very important law of momentum is EQUAL AND OPPOSITE REACTIONS, REGARDLESS of whether it was an elastic or non-elastic collision.

So just by Newton's third law, it shouldnt collapse right? Yes we all know equal and opposite reactions. A fly hitting a big rig Mack truck has an equal and opposite reaction, but who loses? The fly. But the fly also put the same amount of force on the truck. But the truck won. However, you keep ignoring the fact that it wasnt just one floor impacting the floor below it. It was 30 floors moving as one unit impacting the floor below it. Recall the fly and truck? 30 floors that fell the space between the floors (or two depending on how many floors failed), is not going be arrested by the floor below. Yes it is going to exert the same force, but ultimately, the 30+ floors are going to beat the force of one. Now that floor has failed and is now adding its kinetic energy to the 30 floors above it, and crashing down onto the floor below it. According to you something like this should not happen:

But look, it did. The top floors move down in one section, impacting the floor below. According to your version of Newton's third law, the building should not have collapsed. Read about it here:
www.civil.northwestern.edu...

Heh, how about you explain to them how they are wrong according to your vast knowledge of Newton's Third Law. Equal and opposite is just a part of the whole picture. But somehow, you keep ignoring it. And yet, others say its perfectly possible and doable to have a top section crush the remaining section below. And nomatter how many times you say, equal and opposite reaction, it doesnt mean squat if you dont know what is happening.

And once again I prove who really has the holes in their knowledge.

Says the person who thinks that Newton's third law means that the WTC should not have collapsed the way they did.

Originally posted by Yankee451
'splain it to me. Wait...is that you FDNY343? Are we going to go wandering down the KE and V trumps all regardless of M path again?

Wait, so you still don't understand KE?

it's simple.

Use this handy calculator.

Under M put 1

Under V put 10,000

Click Calculate KE.

Tell me what you get.

The mass is only a SMALL portion of the calculation. What REALLY matters is the SPEED at which such object is traveling.

Now, clear out the V field.

Put in a 1 value.

press calculate.

What do you see? .5 j of KE.

Imagine that!! SAME object that weighs 1 kg. has only .5 joules of KE!! IMAGINE THAT!!!

So, yes, I will say that V and KE trump mass alone ALL DAY LONG.

Originally posted by GenRadek
Well it wasnt just a few floors that failed, but some core columns were severed in the impact. Also, when the top section began its descent, it too would cause additional damage to the core as the top is also a solid structure with its own top. Wouldnt that also cause damage to the core section? Nothing had to "remove the resistance" of the lower floors. Once the collapse started, that was it.

How do you know how many floors it was? I thought we couldn't see squat?

Let me explain conservation of momentum as you seem to misunderstand. BOTH the falling floor and the static floor will want to maintain their momentum, remember equal and opposite reaction, this will result in damage to BOTH object as they are both equally pushing against each other. The bottom floors are pushing up against the dropping floor with the SAME amount of force, the dropping floor will want to continue dropping and the static floors will want to keep pushing up against the dropping floor, again this causes damage to both floors. MASS is what makes the difference in damage, less mass more damage.

'Once the collapse started that was it', is not a scientific explanation and is incorrect in so many ways.

I never said they were removed. I asked you would the towers stand if you removed all of the floors in the building.

Why does this matter when it isn't what happened? Again YES I think the central core could stand by itself.

Ah ok, so steel is steel and all steel behaves the same way regardless of size, shape, design, etc. A 1/4" steel beam will react the same was as a 1ft thick steel beams, because, hey, its steel! Good to know ANOK.

So then I guess engineers shouldnt pay attention to such details as steel thicknesses, steel shapes, steel composition, or steel structure design because according to you, steel is steel and doesnt matter what size it is or how it is utilized, be it in a truss design, a column, an I-beam. According to you, each example is interchangeable because its steel, and a truss, as found in the floors of the WTC will be just as good as an I-beam in all situations, loads, fires, structures, because they are all steel. Hallelujah!

All steel melts at the same temperature no matter what its size is. Smaller pieces will heat up quicker than larger pieces. But you want to pretend because they call them 'lightweight' trusses that they will somehow not be able to do the job they were designed to do, and for some reason construction engineers ignored this flaw in their design and used them anyway, and still do in modern buildings.

Sagging from what? Heat and........ loads. Yes heat will cause a steel truss to deform, but add a load on it, and it will deform more rapidly, and readily than a truss without a load. I'm sure you have heard of this before? Also on the floors that were burning, what about the exterior columns that were also exposed to the heat from the fires? Arent they also going to deform?

I agree, but what load was added, and how does this cause the columns they were attached to be pulled in?
No EXTRA load was added, and regardless it is still not going to pull in columns as the building, like ALL buildings was designed to hold more than its own weight, by at least a factor of x2, so you could add a whole extra floor and the trusses would still hold the weight. You keep saying I don't understand how they were designed, but I keep proving it's you who fails in your knowledge. The towers had more than a x2 safety factor.

There was not enough time or heat to cause the massive core columns, or any steel, to be malleable. Even if they did the trusses, being lightweight and weaker, would still not exert a force on the more massive columns.

Wait, what? Where did you ever hear such a ridiculous assumption? How exactly was that caused by the cladding? This is the first time in all these years of 9/11 Truther nonsense, that I heard such a crazy comment. The outer was not bending? So then why do we see the exterior columns bend inward right at the moment the top started to tilt and collapse?
Exterior sag
There was plenty of evidence the floor trusses were sagging, pulling the exterior inwards. Its not the aluminum cladding! Wow!

It's not a ridiculous assumption it's common sense. You can't put aluminum and steel together or you would get galvanic corrosion, so there would have to be a gap between the two. I don't need anyone to tell me this as it is a common engineering FACT.

For example, when aluminum alloys or magnesium alloys are in contact with steel (carbon steel or stainless steel), galvanic corrosion can occur and accelerate the corrosion of the aluminum or magnesium.

corrosion.ksc.nasa.gov...

They can not be placed together, there has to be a gap, and joined by a non corrosive, or isolated, fastener.

You are not seeing any columns bowing, you have no proof of this. All you are seeing is the aluminium bowing inwards.

You can see plenty of deformed and damaged cladding in this pic...

So just by Newton's third law, it shouldnt collapse right? Yes we all know equal and opposite reactions. A fly hitting a big rig Mack truck has an equal and opposite reaction, but who loses? The fly. But the fly also put the same amount of force on the truck. But the truck won.

And do you know why Gen? MASS, the truck has more mass than the fly so the fly loses. In the context of floors impacting floors, they were of equal mass. If you want to think the top dropped as whole block then it still has less mass than the bottom section, 30 floors + 80 floors.

Heh, how about you explain to them how they are wrong according to your vast knowledge of Newton's Third Law. Equal and opposite is just a part of the whole picture. But somehow, you keep ignoring it. And yet, others say its perfectly possible and doable to have a top section crush the remaining section below. And nomatter how many times you say, equal and opposite reaction, it doesnt mean squat if you dont know what is happening.

How am I ignoring equal opposite reactions? I just spent a few posts trying to explain it to YOU.

Says the person who thinks that Newton's third law means that the WTC should not have collapsed the way they did.

Says the person who thinks Newtons laws of motion don't matter if you can't see squat.

reply to post by FDNY343


Why don't light particles obliterate the planets.

Originally posted by Yankee451
reply to post by FDNY343

 

Why don't light particles obliterate the planets.

What is the mass of light?

reply to post by FDNY343


dunno, doesn't matter, right? but probably pretty light (light) because it bounces off everything. sure does move at a good clip though...

The point is that without these limits (which some would call "laws") there could be no universe. Mass matters, so does density.


.

Originally posted by ANOK

How do you know how many floors it was? I thought we couldn't see squat?

Let me explain conservation of momentum as you seem to misunderstand. BOTH the falling floor and the static floor will want to maintain their momentum, remember equal and opposite reaction, this will result in damage to BOTH object as they are both equally pushing against each other. The bottom floors are pushing up against the dropping floor with the SAME amount of force, the dropping floor will want to continue dropping and the static floors will want to keep pushing up against the dropping floor, again this causes damage to both floors. MASS is what makes the difference in damage, less mass more damage.

'Once the collapse started that was it', is not a scientific explanation and is incorrect in so many ways.

Very good ANOK, You have just explained how Newton's 3rd Law works. Now, are you forgetting that one floor vs 30 floors, who is going to lose? Also, its a dynamic mass, where its not just ONE floors moving down, its 30 floors. That one floor at the base, is going to get crushed, but there are 29 more floors above it, that are gonna wanna keep going down, in accordance with momentum. Its not just going to stop because the bottom floor gets crushed by the top of the top section and your "equal and opposite reaction" happens. The floor below the dynamic mass is set for a static loading, not a falling dynamic load of 30 floors. This is where the disconnect is for you ANOK. You keep ignoring the fact that, that top section is moving down whole. One floor below it is not going to stop it. That one floor fails, it is now a part of the mass moving down. Also ANOK, didnt you notice how the exterior columns were slightly forced back during the collapse? What would happen to the floors below it, if all of a sudden, they lost all connectivity to the exterior columns, when the truss seats failed? You wonder why the floors lost resistance below? The building telescoped into itself. That caused the connections to fail rapidly and allowed for the floors to fall down along with the top section gaining speed.

All steel melts at the same temperature no matter what its size is. Smaller pieces will heat up quicker than larger pieces. But you want to pretend because they call them 'lightweight' trusses that they will somehow not be able to do the job they were designed to do, and for some reason construction engineers ignored this flaw in their design and used them anyway, and still do in modern buildings.

But the steel didnt melt did it? A 1/2" thin rod of steel will heat up and deform faster than a 5" thick steel I-beam isnt it?

Its called a "lightweight" truss, ANOK, because it is a lighter structure that allows for less weight and less materials to be used on a building, but allowing for structural rigidity and stability for its designed static loads. If a designer needs to save weight, will he go with a large heavy I-beam, or a lighter steel truss? Hence why they are the most commonly used for structural support. Geeze, I thought you would have at least figured that out. And yes they are great. However, they are also far more susceptible to fires. And yes, there are some people and engineers that believe that this cost cutting in the design of the WTC, may have led to its demise. But few want to admit that. Also add in faulty blown on fireproofing (instead of asbestos or concrete) and it was just bad judgments in the design. I posted the links on it earlier, I suggest you read through them yourself. And also, I cannot find other skyscrapers, which have the same design as the WTC, where they use large light steel trusses as floor supports. Sears Tower doesnt have it. John Hancock doesnt have it. Neither do the Petronas, or the new world's tallest building in Dubai. But a light steel truss will be used for small structures always, and fire codes need to be strictly adhered with these types of structures. Why? ANOK, I dont know.

I agree, but what load was added, and how does this cause the columns they were attached to be pulled in?
No EXTRA load was added, and regardless it is still not going to pull in columns as the building, like ALL buildings was designed to hold more than its own weight, by at least a factor of x2, so you could add a whole extra floor and the trusses would still hold the weight. You keep saying I don't understand how they were designed, but I keep proving it's you who fails in your knowledge. The towers had more than a x2 safety factor.

There was not enough time or heat to cause the massive core columns, or any steel, to be malleable. Even if they did the trusses, being lightweight and weaker, would still not exert a force on the more massive columns.

What extra loads? What about the floors that were damaged by impact? What about floors destroyed by the impact? What about the floors affected by the fires, which according to some police pilots observed to have failed and partially collapsed? What about the exterior columns that were severed, and the core columns, or those affected by fire and impact? How do you know they had a 2x safety failure? Were they designed to account for fires across multiple floors, having 3-4 acres of offices burning, with a 767 inside, and jet fuel? There is a difference between a lost in the fog 707 low on fuel impacting at low speed, and a 1/2-3/4 full 767 @ 450+mph impacting and setting fire to more than 4 floors at the same time. And you have that many floors burning, with impact damage, and that many floor trusses exposed to fire, it was ready to come down. There was not enough to get heated up? one hour? Most trusses in fires fail in 20 minutes.

It's not a ridiculous assumption it's common sense. You can't put aluminum and steel together or you would get galvanic corrosion, so there would have to be a gap between the two. I don't need anyone to tell me this as it is a common engineering FACT.

For example, when aluminum alloys or magnesium alloys are in contact with steel (carbon steel or stainless steel), galvanic corrosion can occur and accelerate the corrosion of the aluminum or magnesium.

corrosion.ksc.nasa.gov...

They can not be placed together, there has to be a gap, and joined by a non corrosive, or isolated, fastener.

You are not seeing any columns bowing, you have no proof of this. All you are seeing is the aluminium bowing inwards.

You can see plenty of deformed and damaged cladding in this pic...

Oh I am aware of the galvanic corrosion, and the fact that the cladding was slightly separated from the columns. However, that is not what we are seeing here ANOK. We are seeing a whole entire wall getting pulled, something that is seen right up to moment it starts collapsing. Why dos it happen right before the collapse? Why wasnt it happening earlier at the areas where there was more visible fire and more intense heat? You are now just making stuff up to cover up the fact that the columns were pulled in. That is called deception ANOK. You refuse to believe, due to your incredulity, the fact that exterior columns were pulled in prior to collapse, because that is what keeps any demolition ideas in check. So you just make the claim that its just the cladding. And you base this on what exactly? Your gut feeling? The same "gut feeling" that the creators of Loose Change had? Because you say so? And yet somehow, all the far more experienced engineers, professionals, even the architects and designers of the WTC, all failed to miss this "obvious" event, but you, the "Man of the Hour", managed to see through the smoke and see the "truth"? Come now ANOK, I know you are not that delusional. You mean to tell me that everyone else that saw the same thing, came to the same observation, is somehow wrong, even the pros? But you are better than they are? Give me a break.

And do you know why Gen? MASS, the truck has more mass than the fly so the fly loses. In the context of floors impacting floors, they were of equal mass. If you want to think the top dropped as whole block then it still has less mass than the bottom section, 30 floors + 80 floors.

Yes each floor was of equal mass. However, it was not just one floor moving down, impacting the next floor. It was the total mass of 30 floors impacting the floor below it. And that is what over came the loading ability of that floor, causing it to fail. It failed, and then added itself to the mass that is moving down, impacting the next floor below it. You can also see how the exterior columns were slightly pushed out as the top was in descent. There was also evidence of truss seats being torn out or off from the collapse. It was 30 floors, + 1 +1 +1 +1 +1 +1 +1 +1 +1 all the way down.

How am I ignoring equal opposite reactions? I just spent a few posts trying to explain it to YOU.

And yet I just showed you a whole paper and video that shows how a smaller section can crush the rest of the structure below it, and you completely ignored it. Did you even bother reading those 12 pages of demolition I posted for you? How do explain that? I understand what they are saying. Do you? According to you, the paper I posted for you, shouldnt be possible.

Says the person who thinks Newtons laws of motion don't matter if you can't see squat.

edit on 3/14/2011 by ANOK because: 911wasaninsidejob

Heh, and yet, you completely ignore the demolition paper. Try and explain that.

Originally posted by Yankee451
reply to post by FDNY343

 

dunno, doesn't matter, right? but probably pretty light (light) because it bounces off everything. sure does move at a good clip though...

The point is that without these limits (which some would call "laws") there could be no universe. Mass matters, so does density.


.

Really? So Mass time velocity plus DENSITY = KE? I seem to have missed that.......

Also, way to twist my words.

reply to post by FDNY343


You sure do a lot of scoffing and ridiculing for someone who has brought absolutely nothing to the table. Light particles are real and they travel pretty fast, wouldn't you say? If mass and density of material don't matter, why don't light particles destroy everything? They move pretty quickly (speed of light and all), so what's your beef? It's just a representation of your own logic.

Take a video of yourself using your Kung Fu KE skills...video tape yourself punching out the corner of a building or something along those lines. Take a baseball bat and cut down an oak tree.

Whatever you do, don't read about the subject.

Originally posted by Yankee451
reply to post by FDNY343

 

You sure do a lot of scoffing and ridiculing for someone who has brought absolutely nothing to the table. Light particles are real and they travel pretty fast, wouldn't you say? If mass and density of material don't matter, why don't light particles destroy everything? They move pretty quickly (speed of light and all), so what's your beef? It's just a representation of your own logic.

Not when that "thing" that you are trying to equate it to, has NO mass.

But, again, you still do not understand what my point was. The MASS part is not as important to KE as the SPEED part is! GD!! Why is this so hard for you to understand?

Jim has the same problem. Imagine that.


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Anok, there is a post here waiting for your reply with lots of fact, and links, and data.

reply to post by FDNY343


So mass matters?

Originally posted by FDNY343
But, again, you still do not understand what my point was. The MASS part is not as important to KE as the SPEED part is! GD!! Why is this so hard for you to understand?

You are wrong once again.

If a fly hits a car windshield, remember Newtons 3rd law equal opposite reactions, the force on the windshield is the SAME as on the bug. What makes the bug go splat, KE or MASS?

It's the mass mate. Both objects are putting the same force on each other, the only difference is the mass.

Consider this question...

3. Miles Tugo and Ben Travlun are riding in a bus at highway speed on a nice summer day when an unlucky bug splatters onto the windshield. Miles and Ben begin discussing the physics of the situation. Miles suggests that the momentum change of the bug is much greater than that of the bus. After all, argues Miles, there was no noticeable change in the speed of the bus compared to the obvious change in the speed of the bug. Ben disagrees entirely, arguing that that both bug and bus encounter the same force, momentum change, and impulse. Who do you agree with? Support your answer.

www.physicsclassroom.com...

Ben Travlun is correct.

The bug and bus experience the same force, the same impulse, and the same momentum change (as discussed in this lesson). This is contrary to the popular (though false) belief which resembles Miles' statement. The bug has less mass and therefore more acceleration; occupants of the very massive bus do not feel the extremely small acceleration. Furthermore, the bug is composed of a less hardy material and thus splatters all over the windshield. Yet the greater "splatterability" of the bug and the greater acceleration do not mean the bug has a greater force, impulse, or momentum change.

Answer