An email from a Conspiracy theorist, and I have no idea how

[Undesired Walrus]

Given my bubble video, somehow, I have no idea how, a truther called "Heath" who calls himself a structual engineer has found my email address. I really am amis to how this is possible, as I believe e^n put up my video on his server.

Conspiracy!

Anyway, You are better than this stuff than me. Help me out a little please?

OK. There's two ways to make a tower collapse vertically downwards - 1) suddenly destroy a section so that part of the tower suddenly falls on the lower sections causing a collapse or 2) evenly weakening a similar section continuously. As parts collapse away more of the tower is weakened until it's all gone.

You will notice the conspiracy theory uses method 1) (bombs in the basement or wherever) while the official report uses 2) - the fire weakening the steel and causing the floors to collapse.

If the fire had weakened the steel supporting a floor (a claim that is very open to debate in itself) it would have had to be the case that all of the supports of that floor gave way at the same time to create a floor that falls 10 feet. You can tell me how many supports each floor had but I suspect it was a lot - statistically all of them failing at once is impossible and so the more likely scenario is that the floors collapse gradually - no big shock and no collapse.

What's more likely is the tower burning until the section with the fire was just a tube and then keeling over (remember the orientation of the exterior steel girders make them very resistant to heat deformation under gravity. A horizontal beam will sag but a vertical beam will not.)

I bet there have been computer simulations done to try and see what happens. I don't suppose you know of any do you?

 

[uk_dave]

OK. There's two ways to make a tower collapse vertically downwards - 1) suddenly destroy a section so that part of the tower suddenly falls on the lower sections causing a collapse or 2) evenly weakening a similar section continuously. As parts collapse away more of the tower is weakened until it's all gone.

You will notice the conspiracy theory uses method 1) (bombs in the basement or wherever) while the official report uses 2) - the fire weakening the steel and causing the floors to collapse.

He's already forgotten about the damage caused by the plane impact

If the fire had weakened the steel supporting a floor (a claim that is very open to debate in itself)...

Bollocks, as any self respecting structural engineer knows since they have to deal with fire protection to steel members on a daily basis

... it would have had to be the case that all of the supports of that floor gave way at the same time to create a floor that falls 10 feet. You can tell me how many supports each floor had but I suspect it was a lot - statistically all of them failing at once is impossible and so the more likely scenario is that the floors collapse gradually - no big shock and no collapse.

utter rubbish. The fire affected a number of floor trusses made up of thin steel sections. These weakened, sagged and caused their connections to the outer columns to pull those columns inwards. The columns then reached the limit at which their connections could resist the pull away from upright and failed catastrophically. This resulted in the floor falling onto the one below, overloading it and causing it to fail.

What's more likely is the tower burning until the section with the fire was just a tube and then keeling over (remember the orientation of the exterior steel girders make them very resistant to heat deformation under gravity. A horizontal beam will sag but a vertical beam will not.)

Is he suggesting that the fire would have consumed everything, including the floors until the tower was just a hollow tube?
And then fall over....like....a..........a.......... tree?

I bet there have been computer simulations done to try and see what happens. I don't suppose you know of any do you?

what a fool.

 

[uk_dave]

Having re-read his tube comment, I now see that he is probably suggesting that the floors would all collapse internally but that the structure would remain standing until someone at ground level leaned on it.

No structural engineer would display such a blatant lack of understanding of an engineered structure.

 

[MRC_Hans]

Given my bubble video, somehow, I have no idea how, a truther called "Heath" who calls himself a structual engineer has found my email address. I really am amis to how this is possible, as I believe e^n put up my video on his server.

Conspiracy!

Anyway, You are better than this stuff than me. Help me out a little please?

OK. There's two ways to make a tower collapse vertically downwards - 1) suddenly destroy a section so that part of the tower suddenly falls on the lower sections causing a collapse or

Incorrect. The natural way for any structure to collapse is vertically downwards, in the direction of gravity. For a structure to collapse in any other way, i.e. keel over, something must act to transfer the vertical force of gravity into a howizontal direction.

2) evenly weakening a similar section continuously. As parts collapse away more of the tower is weakened until it's all gone.

Incorrect. Parts do not collapse away till they are all gone, they bend or otherwise deform so the force is transferred to the remaining members. When the sum of the force on the remaining members exceed their strenght, they fail catastrophically.

You will notice the conspiracy theory uses method 1) (bombs in the basement or wherever) while the official report uses

That is only some of the CTs, but OK.

2) - the fire weakening the steel and causing the floors to collapse.

This is not equal to the formulation of #2 above. This second formulation of #2 is, however, correct.

If the fire had weakened the steel supporting a floor (a claim that is very open to debate in itself) it would have had to be the case that all of the supports of that floor gave way at the same time to create a floor that falls 10 feet.

1) No, it is not under serious debate.

2) The rest is a strawman. Once enough supports fail for the remaining to be overloaded by the redistributed weight, they will fail in (very) rapid succession.

You can tell me how many supports each floor had but I suspect it was a lot - statistically all of them failing at once is impossible and so the more likely scenario is that the floors collapse gradually - no big shock and no collapse.

The scenario is wrong. Try this: Suspend a heavy weight from a rope (no need to suspend it very high, half a foot will do ). The rope should be one with a breaking strenght of about twice the suspended weight.

Now start cutting the rope, fibre by fibre. Do you need to cut them all before the rope breaks and the weight falls? Answer: No, when you reach the point where the remaining fibres can no longer carry the weight, the rope breaks.

What's more likely is the tower burning until the section with the fire was just a tube and then keeling over (remember the orientation of the exterior steel girders make them very resistant to heat deformation under gravity. A horizontal beam will sag but a vertical beam will not.)

If it is weakened it will, but we have proof of the mechanism of how the "tube" was breaking down: Several pictures and videos show how the sides of the tower around the fire zone are pulled inwards: The sagging inner structures excerted a horizontal (inwards) pull. As long as the inner structures (floor trusses) remained rigid, they transferred the load to the outer girders vertically, but once they started sagging, they pulled inwards.

I bet there have been computer simulations done to try and see what happens. I don't suppose you know of any do you?

Yes, the effect of sagging trusses (both from being heated and from stuff collapsing on them) has been shown in computer simulations. They precisely imitate the actual observations.

Finally, on "keeling over":

Collapsing buildings can, and sometimes do, keel over and fall more or less on their side. However, the process of keeling over requires the falling structure to rotate from its original, vertical, orientation. Such a rotation can only happen if there is some force acting on it, and this force must be powerful enough to transfer the pull of gravity for long enough to impart a rotational movement of the falling mass.

The idea that if you hack away the supports of a building from one side, then it must keel over is fundamentally flawed. For it to happen, the surviving supports must be strong enough to carry the weight of the structure above them, while bending as a hinge, for enough time that a rotational movement is initiated. This requires a redundance of strength that is not present in a very large building.

Hans

 

[Alferd_Packer]

A horizontal beam will sag but a vertical beam will not.

A vertical stuctural member is called a column, not a beam.

Columns "squash" under heat deformation.

 

[The Doc]

Looks to me like you have someone pretending to be a structural engineer. Either that or a structural engineer that got his degree from a box of Cheerios.

 

[Gravy]

Looks to me like you have someone pretending to be a structural engineer. Either that or a structural engineer that got his degree from a box of Cheerios.

I agree about the pretending. I always laugh at the "everything would have had to fail simultaneously" canard. The deniers always expect the forces of nature to operate on their schedule. In their world things can't fail sequentially but rapidly. Clunkity-clunk!

 

[MarkyX]

I remember getting these emails by so-called "structural engineers" as well. One guy who emailed me said that the fires in the towers didn't go higher then 200 degrees C, and I simply asked him "You're telling me that all the material burning, open air, and the jet fuel burning would be not hot enough to cook a pizza" ? He said yes.

We've all seen examples of 9/11 deniers pretending to be heroes or scientists like "Guy Razor" to "Mike the EMT". This shouldn't be a shock to anyone.

 

[T.A.M.]

Well keep a dialogue with him, then simply ask him for his full name and university he got his Engineering degree from. If he actually gives you the info (highly doubtful) it would be easy enough to check.

To be honest, this letter stinks so much of a fake, that it may not even be worth your time to do the above.

TAM

 

[Loss Leader]

For what he's proposing, it seems like he's assuming the towers were built in a traditional skeletal framework which is just ... wrong.

 

[NoZed Avenger]

For what he's proposing, it seems like he's assuming the towers were built in a traditional skeletal framework which is just ... wrong.

I disagree. He'd have to make major revisions and many corrections before I would be willing to concede that he was merely "wrong."

 

[kookbreaker]

Remember, in the trooth movement its OK to lie about being an engineer when you are not. Its all for the trooth!

 

[kookbreaker]

BTW, If I were you I would reply using the info you've gotten here, then insist he prove in some form that he has the degrees he claims. Note to him that you should not have to put up with liars from a 'truth' movement.

 

[Undesired Walrus]

I agree about the pretending. I always laugh at the "everything would have had to fail simultaneously" canard. The deniers always expect the forces of nature to operate on their schedule. In their world things can't fail sequentially but rapidly. Clunkity-clunk!

Hooray your new signature Gravy!

Seen him around Manhattan recently?

 

[The Silver Shadow]

At least you get something from a "structural engineer." I'm still receiving hatemail on Facebook and I have to laugh at some of them because the twoofers can't string a sentence together and yet they claim they have the answers!

Anyhow, like TAM said, ask for his degree and where he graduated from. If he gives you the name of anywhere, check to see if it's a Diploma Mill
http://en.wikipedia.org/wiki/Diploma_mill

 

[Darth Rotor]

I agree about the pretending. I always laugh at the "everything would have had to fail simultaneously" canard. The deniers always expect the forces of nature to operate on their schedule. In their world things can't fail sequentially but rapidly. Clunkity-clunk!

In re your sig link to Annie Hall, I can still recall a favorite line from that underwhelming movie, and sure enough, it's early in the fillm:

ROB
Let's get the hell outta this crazy city.
ALVY
Forget it, Max.
ROB
We move to sunny L.A. All of show business is out there, Max.
ALVY
No, I cannot. You keep bringing it up, but I don't wanna live in a city where the only cultural advantage is that you can make a right turn on a red light.

At the time, it was a good gag, but it has lost something in context, sadly.

DR

 

[chippy]

At least you get something from a "structural engineer." I'm still receiving hatemail on Facebook and I have to laugh at some of them because the twoofers can't string a sentence together and yet they claim they have the answers!

Like who? I could fire back at them.

 

[BillyRayValentine]

For it to happen, the surviving supports must be strong enough to carry the weight of the structure above them, while bending as a hinge, for enough time that a rotational movement is initiated.

I know you understand this, but I would clarify one thing so as not to confuse the truth-bots. The issue isn't so much rotation, but the horizontal shifting of the section's center of gravity. Rotation, in and of itself, does nothing to alter the location of an object's COG. (Not the object's COG, per se, but the location of its COG relative to a fixed point in space.) Only some manner of lateral force can do this.

Looking at the south tower collapse (plenty of unambiguous videos exist), we can see that the top section was, in fact, imparted with some rotational spin at the moment of collapse. The east side buckled first, and the building immediately tilted in that direction. And at least momentarily, the uncollapsed portion did indeed act as a hinge and shifted the section's COG. The operative word, however, is momentarily. As soon as the COG was shifted even a small amount, the top section and its hundred thousand tons of bulk was no longer centered and properly distributed over the support structure. Complete collapse ensued on all sides, as it had to. After that first moment, the hinge effect (lateral force) was over and gravity ruled the day.

In fact, the manner of collapse began working against this residual (and negligible) lateral momentum almost immediately. An observation that rarely gets noted is that after the building started rotating to the east, the corner along the eastern side of the collapsing section immediately began knifing through the building below. It essentially behaved like a wedge, and with several predictable results. First, debris was violently ejected to both the east and west. Second, forces began working against the "spin" of the collapsing section almost immediately. The net result was a gentle and slowing rotation as the section fell. And any lateral momentum that remained from the first moments of the collapse was all but arrested.

 

[The Silver Shadow]

Like who? I could fire back at them.

I usually delete them, but I have two that I haven't yet sent to the trash bin. I have replied to them all...

 

[Undesired Walrus]

And he replies!

etc etc...

This may be true for cricket balls but it certainly aint for buildings. Ask any Structural Engineer and they'll tell you that it's actually very hard to get a building to collapse vertically downward.

In response to the rope with a weight

What a pointless example. A building is a far more complicated system than a rope with a weight. Think about this - a cardboard box with a big weight on top of it. How does it collapse? Well what a surprise! it kinks in one side and keels over.

I do find it quite funny that someone could be as moronic as you are being thinking that you're coming up with good arguments to support your view when in actual fact they are just like you - much to simple to be of any use.

For every engineer you'll find to say one thing you'll find another to say the exact opposite (that's the thing with engineers. They're basically physicists that aren't clever enough to do proper physics.)

As for your strong interest in a topic you can't even spell, I'm afraid I can only snort derisively at you. Consider it done.

After the plane strike the buildings were what's called a chaotic system. I did have a think about trying to explain that but I don't think I'll bother to be honest. you'll just have to take my word for it that the most important property of chaotic systems is that a very small change in the initial conditions (the position of the plane strike. The scale of the fire and the distribution of mass above the weakened section) produces a very large change in the final state of the system, in this case the building. The probability of the buildings collapsing vertically is vanishingly small because there are very many more ways for it to topple sideways that the one vertical collapse.

Of course, you can identify with vanishingly small things much more easily than I can.

????? Any opinions??