structural engineer leslie robertson interview

Originally posted by Achorwrath
There were many times where I heard nothing at all but the words would pop up on the screen saying things like; did you hear that?

I'm not sure what kind of sound system you have on your computer, but I have a 5.1 surround sound and my subwoofer is very loud. One really needs a subwoofer to hear and feel the loud, low-level booms. I'm not sure how those low-level booms would sound on speakers with no true bass or without a subwoofer.

Originally posted by Achorwrath
If you are already inclined to believe it was demo

When I very first saw this documentary, I didn't know anything about controlled demolitions or 9/11 truth or any of that. This was just one of the 9/11 documentaries that were out at the time I got "introduced" to 9/11 truth. So I had no inclination at all that there was a controlled demolition at that time. I only heard claims and I set out and did my own research before believing either way.

Originally posted by Achorwrath
see if I can ID pulses in the sound wave to cooborate some of the video

So you didn't like their sound analysis? Well, if one doesn't have a subwoofer, they're not going to really appreciate the explosions anyway.

Either way, it is almost imperative to have a subwoofer and good bass to hear these booms.

Originally posted by Achorwrath
I will say it is interesting but certainly not conclusive.

You are correct that a piece of evidence here or a piece of evidence there is not conclusive, but if you add all the pieces together, it becomes very conclusive.

[edit on 19-3-2009 by _BoneZ_]

You are assuming I do not have one, assumptions are dangerous.

In fact I do have that I have an Asus Xonar DX1 (192db SNR) running optical (toslink) out to a nice set of Logitech THX certified 5.1 surround speakers.

My subwoofer still did not produce anything for many of the sounds in that video.

I never take someone elses findings for granted.

I like to analyze them myself.

I do know about controlled demolition and explosives and from what I am hearing I do not hear anything that jumps out and says demolitions

I hear booms but again nothing conclusive.
In fact the booms are very close to the sounds from the Big Blue video.

Originally posted by Achorwrath
You are assuming I do not have one, assumptions are dangerous.

How am I assuming when my very first sentence said "I don't know what kind of sound system you have"? I never once assumed you did or did not have a subwoofer.

I simply stated that one needs a subwoofer to appreciate the booms in the video.

Originally posted by Insolubrious
Big blue crane collapsed in one direction and didn't break up into little pieces!

I was comparing SOUNDS. The SOUNDS of metal breaking, hitting other metal. It was a VERY VALID comparison.

Originally posted by Insolubrious
To Cameron Fox, What if that van was made of structural steel with a few inches thickness each side? Wouldn't that make your pumpkin comparison a little more fair?

As long as we strap some massive jet engines on either side of it. Talk about being a little fair.

Originally posted by _BoneZ_

I'm not sure what kind of sound system you have on your computer, but I have a 5.1 surround sound and my subwoofer is very loud. One really needs a subwoofer to hear and feel the loud, low-level booms. I'm not sure how those low-level booms would sound on speakers with no true bass or without a subwoofer.

Please watch the following video (under 3 minutes)

The following is NOT needed:

5.1 surround sound

sub-woofer

true bass

What is recommended:

Your ears, basic speakers, and or cheap headphones.

reply to post by CameronFox


I'm not sure what the purpose of this video is unless you're trying to say the WTC was not a controlled demolition. It was not controlled in the fact that controlled demolitions are controlled not to hit buildings.

If you're a planner of 9/11, you're going to make the demolition of the WTC as less obvious as possible. It's not going to be completely obvious or conventional. There are some conventional aspects of the demolition of the WTC, but there are also unconventional.

Open your mind a little wider and consider the possiblility.

Originally posted by CameronFox

Originally posted by Insolubrious
To Cameron Fox, What if that van was made of structural steel with a few inches thickness each side? Wouldn't that make your pumpkin comparison a little more fair?

As long as we strap some massive jet engines on either side of it. Talk about being a little fair.

Sure, play it your way, let's put some jet engines on your pumpkin. But your jet engines would only send your pumpkin flying at 500mph, not 900mph, and the pumpkin still wouldn't punch through. I doubt the engines would either so your comparision is highly flawed and still very much way off.

Originally posted by Seany
I dont need Re search......... I have Real life

Yet you claim clapping your hands together compresses the air?

Or does the air rush out of the way of the clapping hands? I.E. not compress.



[edit on 3/20/2009 by Griff]

Originally posted by Griff

Originally posted by Seany
I dont need Re search......... I have Real life

Yet you claim clapping your hands together compresses the air?

Or does the air rush out of the way of the clapping hands? I.E. not compress.



[edit on 3/20/2009 by Griff]

Clapping your hands attempts to compress the air between them which causes the air to escape compression through the sides (path of least resistance)

So with your argument there, wouldn't the air between the floors follow the same rules?

Path of least resistance would be out the windows (broken ones first of course, down and up the core, out of the hole in the side of the building.

an explosion is nothing more than displaced air caused by the combustion of the material that has been packed tightly (in most cases) if I remember correctly detcord burns at about 15000feet per second for mild Det Cord and faster for others (up to 30k FPS).

here is the definition of an explosion:

An explosive reaction that moves through an explosive material at a velocity greater than the speed of sound in the material. A detonation is a chemical reaction given by an explosive substance in which a shock wave is formed. High temperature and pressure gradients are generated in the wave front, so that the chemical reaction is initiated instantaneously. Detonation velocities lie in the approximate range of 1,400 to 9,000 m/s = 5,000 to 30,000 ft/s; slower explosive reactions, which are propagated by thermal conduction and radiation, are known as deflagration.
A chemical reaction in which the reaction front advances with a speed which exceeds the velocity of sound in the material. In this case, energy is transmitted from the reacted to the unreacted material by a shock wave. Burning rate usually in excess of 2,000 meters / second.

source

the expansion of the bruning material is what causes the heat and shock wave

So clapping your hand can be made as a valid comparison.

Remember that explosions expand on all sides unless directed.

This is the reason for shaped crages they force the blast in one direction.

It is also why in controlled demo of a concrete structure they bore a hole into the pillar and seal it behind. It concentrates the force of the blast into the column.

Originally posted by Achorwrath
Now each floor would have to AT LEAST support the wieght of the floor above. but lest say it can support 4 making this support X using Griff's FoS of 2.5 we have each floor supporting 2.5X.

Actually, NIST found each floor could hold 6 times their own weight.

North tower, floor 93 lost 15-16 supporting colms (according to photographs) this means that that floor alone lost 25% of its outer support. None of the trusses along that portion were suppoting the floor anymore. this is without even touching the possibility that central core beams were afected.

You can't have unaffected floor slabs and have the plane make it to the core at the floor slab.

So floor 93 is now (2.5X)*.75= 1.875X

Actually, it would be more like: (6X)*.75= 4.5X

Lets heat up the metal bolts now according to posts here by Griff, the metal reached at least 250c
so lets give it a 10% reduction in strength although it is probably more like 15%

1.875X*.9 = 1.6875X

4.5X * .9 = 4.05X

now above floor 93 you have 17 floors 17 / 4 = 4.25X This is the weight shown as a factor of support.

1.6875X < 4.25X

At no time would the unaffected floors above floor 93 bear down on floor 93 until collapse. So, I have no idea why you are saying there would be an added weight on floor 93 to cause it to fail.

BTW, what of the columns? You know, the things that actually hold buildings up, not floors.

Simplified yes. but still showing a grealy increased structural demand.

What greatly increased structural demand? I'll repeat, unless the floor above has failed, it would not be bearing on the floor below.....so no "increased structural demand".

Now since the fires were mainly on the oposite side of the impact hole,

So why did we calculate a 10% loss of strength before when the fires were on the other side? To make your calculations look correct?

This means there would have been a unifom loss of support across the affected floors,

How does fire on one side and plane damage on the other cause a "uniform loss of support"?

The South tower actually had more floors above the point of impact to deal with (77-85)

It was also hit in a way that the core was mainly missed.

Originally posted by CameronFox

Originally posted by _BoneZ_

I'm not sure what kind of sound system you have on your computer, but I have a 5.1 surround sound and my subwoofer is very loud. One really needs a subwoofer to hear and feel the loud, low-level booms. I'm not sure how those low-level booms would sound on speakers with no true bass or without a subwoofer.

Please watch the following video (under 3 minutes)

The following is NOT needed:

5.1 surround sound

sub-woofer

true bass

What is recommended:

Your ears, basic speakers, and or cheap headphones.

Nice propaganda video Cameron.

Did you notice that there was no sound at all when they showed the towers and 7 collapsing? Other than the music of course.

Hell, you can even hear the collapses of the other buildings over the music but not a single sound byte from the videos of the towers and 7.

A little bit deceiving eh? Since we should at the very least hear these massive booms of steel impacting steel as they collapsed correct?

Or is the collapse of a 110 story building silent?

All I have to say about that video is shame on you Cameron:

Again, you throw NIST around while saying they are lying.

You cannot have it both ways.

The structural blue prints show sections of 4 so each floor was capable of supporting 4 times its wieght or =X.

if you want to say 6 times ok it is still X your claimed FoS makes it 2.5X NOT 4.5 X

I covered the outer columns, remeber I said that on floor 93 alone there were between 15-16 completely gone.

The floor on floor 96 was reported to have about a 320 Sqt Ft section destroyed.

You are only viewing part of the post.

so now X is 6 floors.

Great 2.5X is still valid as X is a variable.

2.5X *.75 = 1.875X how is that not a vlid calcualtion?

so now we use 6 instead of 4 - 17 / 6 = 2.833333

Still over limit.

I am basing all of this on floor 93 but also bear in mind that loss of support across multiple floors is cumulative not exclusive.

Support lost on two sides is uniform loss of support.

The outer colums are not capable of supporting the wieght above them without each sucessive floor.

The outer columns loose stiffness and the connections (bolts and welds) fail.

I am not sure how you get that the plane hit would have missed the core?

The plane traveld through the building, parts flew out the oposite windows and dmamage the oposite side of the building, in fact there is evidence of damage on three sides of both towers.

Originally posted by Achorwrath
Clapping your hands attempts to compress the air between them which causes the air to escape compression through the sides (path of least resistance)

This would be the opposite of actually compressing then, correct?

So with your argument there, wouldn't the air between the floors follow the same rules?

Sure. Does the air get shot out in a stream or does it get shot out in all directions equally?

Path of least resistance would be out the windows (broken ones first of course, down and up the core, out of the hole in the side of the building.

50 stories below collapse wave in the path of least resistance when the entire top is open to the air?

the expansion of the bruning material is what causes the heat and shock wave

So clapping your hand can be made as a valid comparison.

Clapping your hand is a comparison for what? An explosion? No. Air compression? No. Air being forced out? Yes.

Remember that explosions expand on all sides unless directed.

This is the reason for shaped crages they force the blast in one direction.

It is also why in controlled demo of a concrete structure they bore a hole into the pillar and seal it behind. It concentrates the force of the blast into the column.

And you use this as an argument to tell me that the jets of forced air are not from shaped charges?

Yes I actually do use it,
And it is valid.

You understand that the force you feel is the compressed edge of the expading air.

That is why you feel it, it is denser air at the leading edge of the expansion.

Air follows Newton's laws too. the air molecules want to stay at rest and are pushed into each other as the internal expansion occurs.

why are all the jets consistant with the areas of window placement?
If they were aligned along the columns that would be different.

now lets add something else,
The outer facade was similar to concrete and sheathed in aluminum

Concrete crumbles easily under the right pressure and creates a large amount of dust.

if you bend the material concrete is attached to violently enough it will statter away from the point of compression creating a "jet" of shrapnel and dust.

Originally posted by Achorwrath
Again, you throw NIST around while saying they are lying.

You cannot have it both ways.

As I have said before. One can use NIST for their data. I don't accept NIST's conclusions with that data, but I do accept that data.

The structural blue prints show sections of 4 so each floor was capable of supporting 4 times its wieght or =X.

As I've said before, this doesn't mean the floors can hold 4 times their weight just because they are built in sections of 4. The columns are what holds the weight of each individual floor.

But, NIST found that each floor had a FoS of 6. Meaning that each floor could hold 6 times its own weight.

Now, this is different than the FoS for the columns as the columns hold all the floors.

So, you are mixing up factors of safety of floors and columns. BTW, I have heard the columns had more than just 2.5 FoS.

Support lost on two sides is uniform loss of support.

In a 4-sided building?

The outer colums are not capable of supporting the wieght above them without each sucessive floor.

What? The Vierendeel truss gave them lateral support also.

The outer columns loose stiffness and the connections (bolts and welds) fail.

I am not sure how you get that the plane hit would have missed the core?

Look into WTC 2 and the damage done by the plane. Only part of the wing would have made it to the core (if that).

Originally posted by Achorwrath
why are all the jets consistant with the areas of window placement?

You mean on a building that has a window wall?

now lets add something else,
The outer facade was similar to concrete and sheathed in aluminum

Where did you get this information?

Originally posted by Griff

Nice propaganda video Cameron.



All I have to say about that video is shame on you Cameron:

This video was not meant to be used as propaganda....it was so you could hear the audio from the detonations. Something that is missing from ALL 911 videos that show the collapse.

So let's do it this way, shall we?









This is a pretty good one, pretty funny too:



3 minutes starts the demo

Originally posted by Griff

Originally posted by Achorwrath
Again, you throw NIST around while saying they are lying.

You cannot have it both ways.

As I have said before. One can use NIST for their data. I don't accept NIST's conclusions with that data, but I do accept that data.

The structural blue prints show sections of 4 so each floor was capable of supporting 4 times its wieght or =X.

As I've said before, this doesn't mean the floors can hold 4 times their weight just because they are built in sections of 4. The columns are what holds the weight of each individual floor.

But, NIST found that each floor had a FoS of 6. Meaning that each floor could hold 6 times its own weight.

Now, this is different than the FoS for the columns as the columns hold all the floors.

So, you are mixing up factors of safety of floors and columns. BTW, I have heard the columns had more than just 2.5 FoS.

Support lost on two sides is uniform loss of support.

In a 4-sided building?

The outer colums are not capable of supporting the wieght above them without each sucessive floor.

What? The Vierendeel truss gave them lateral support also.

The outer columns loose stiffness and the connections (bolts and welds) fail.

I am not sure how you get that the plane hit would have missed the core?

Look into WTC 2 and the damage done by the plane. Only part of the wing would have made it to the core (if that).

Hang on - you have been preaching an FoS of 2.5 for quite a while and now you pull 6 out of the air?

6 is the maximum load not the FoS
if the maximum load is 6 you apply the FoS on top of that

X is the max load the floors should be able to support UNDAMAGED.

FoS if used as a factor makes it 2.5X

your comment on lateral support actually helps to prove what I am saying.

On floor 93 alone you lost 25% lateral support.
Now take floors 94-101 into account and how much lateral support did you loose on one side?

Adding the fire in shows that there were weakening forces on multiple sides.

Uniform on two sides is still uniform.

Or would it make you happier if I said Uniform Loss of Support on two sides?

Lets looks at this image:


This is the oposite side of the impact on South Tower

Look at the amount of damage there (ignoring the NPT markup). So you are saying that the plane hit hard enough internally to kock the facade off and did not hurt any conectors or welds?

If you look closely you can se pushed out spandrel plates and disrrupted joints.

Originally posted by CameronFox
This video was not meant to be used as propaganda....it was so you could hear the audio from the detonations. Something that is missing from ALL 911 videos that show the collapse.

And I'll state this again. ALL 9/11 video footage I have seen has been without audio because I can't even hear the collapses (you know, those loud booms you claim are steel impacting steel).

Please post a video where you can actually hear the collapses.

Unless 9/11 eyewitness is the only one to pick up these massive booms from steel impacting steel?

So let's do it this way, shall we?

This is a pretty good one, pretty funny too:

3 minutes starts the demo

Again: Please post a video of the towers and 7 that has not had the sound taken out or filtered/edited.