WHERE DID THE TOWERS GO? by Dr. Judy Wood, Ph.D

[Jeffrey Orling]

Sorry, I thought it was obvious.. Sandero.

[Kyle Burnett]

Yeah, that was my guess, but I couldn't rule out the possibility that you might have been someone else who posts less and hence I hadn't run across over there. Anyway, in regard to your previous post:

...and to most engineers who study this it looks like a duck and quacks like a duck so it IS a duck and that duck is a progressive floor failure from over loading.

So where can one find other examples of this supposed duck? Again, I've seen simulations of top-down building collapses, but none that come down anywhere nearly as quickly and completely as the towers did. Most engineers can agree on how many angels can dance on the head of a pin for all I care; but absent any semblance of experimental confirmation, you've got nothing to prove your claims of ducks are anything more than a snipe hunt.

[Jack White]

Yeah, that was my guess, but I couldn't rule out the possibility that you might have been someone else who posts less and hence I hadn't run across over there. Anyway, in regard to your previous post:

...and to most engineers who study this it looks like a duck and quacks like a duck so it IS a duck and that duck is a progressive floor failure from over loading.

So where can one find other examples of this supposed duck? Again, I've seen simulations of top-down building collapses, but none that come down anywhere nearly as quickly and completely as the towers did. Most engineers can agree on how many angels can dance on the head of a pin for all I care; but absent any semblance of experimental confirmation, you've got nothing to prove your claims of ducks are anything more than a snipe hunt.

In the history of the world, how many buildings have collapsed
FROM THE TOP DOWN? Absent proof of that happening, which
I have been unable to discover, we are left with the unique fact
of TWO BUILDINGS COLLAPSING FROM THE TOP DOWN in a single
hour...and an undamaged building a few hours later from the
BOTTOM UP. Show us an instance of this EVER HAPPENING in the
history of the world. Buildings just do not collapse from the top
down...THEY COLLAPSE BECAUSE THE SUPPORTS UNDERNEATH
CAN NO LONGER BEAR THE WEIGHT ABOVE.

Orling cannot present us with one case of TOP DOWN COLLAPSE,
or he would have by now. It is simply his "theory"...ducks or no
ducks, snipes or no snipes.

Jack

[Jeffrey Orling]

1. Buildings rarely collapse. They are designed to stand and carry the normal expected loads. And typical office floors, hotel floors and apartment floors are rarely loaded anywhere near the limit and over the entire floor area.

2. It's rather difficult TO impose an excessive load any floor in a uniform manner in any typical application. For example, if could do this if you turned a WTC tenant floor into a warehouse floor and loaded it up to the ceiling, with for example steel hardware. Of course what would happen as the shelves were filled with inventory the floor would begin to sag and someone would say... We're over loading this floor and we'll have to store the inventory on a stronger floor or in a warehouse designed for such loads.

3. The towers floors collapse because they experience an extremely rare totally unanticipated over load when the floors above were destroy and became the imposed load of 1000's of pounds per square foot on a floor designed to support 58#/SF. You could drop a wrecking ball or a tug boat or a tank on the floors and destroy them.. or a stack of safes or a extremely heaving equipment, motors, transformers, steel beams and so forth.

Side note: Recently I designed a roof terrace which was supported on steel beams which spanned over the existing roof into the parapet walls which were strong enough to take the load. The problem the contractor had was where to store all the steel beams on the roof BEFORE they were installed in beam pockets in the parapet wall. If he stacked them up in a neat pile ON the roof, it would likely collapse! So he had to rest them on top of two walls which formed the corner of the building on top of the parapet so the weight was not on the ROOF, but on the load bearing walls.

3. The twin towers were a very unique design with very lightweight construction for the very long span floor system. Rather than have a field of columns distributed throughout the floor, the design called for pre fab assemblies with would rest between the facade and a beam attached to the perimeter of the core. Cheap, fast to build, lightweight.. column free for flexible interiors... but vulnerable to the failure they experience. The Empire State Building... where I worked for a time on the 74th floor had a completely different structural system with columns in a 25' (or so) grid with masonry exterior walls supported by the frame. The ESB could not collapse as the twin towers... but perhaps one bay in the grid might if a huge load was imposed within THAT bay.

4. Because the floor system was a composite with the embedded trusses it also acted as bracing for the facade and for one side of the perimeter core columns. The facade most definitely required the floors for bracing. Without the floors the facade could not stand long.... too tall and too thin. The core columns could stand much like a steel grid frame of a typical high rise structure without the floors outside the core for bracing.

5. But even the core columns required bracing to stand 1362 feet tall. Absent the bracing the core columns were unstable and would collapse from their own weight. Surely you don't think a column which is 22"x52" made from 36' sections welded together and stacked up AND tapering down to as small as 12x12 at the top could stand with bracing or guys 1,363 feet tall.... or 700 feet tall. Or could remain stable with tons of debris collapsing and crashing around them?

So first the floors collapsed... then the facade fell away and finally the core columns buckled when the bracing WITHIN the core was destroyed by falling debris... inside the core.

[Jeffrey Orling]

Jack,

Structures don't collapse without stress or some mechanism or energy input to destroy them. A top down collapse has to be driven from the very top... as in a huge weight.. such as a wrecking ball being dropped on them. And that is not gonna happen for many reasons.

The twin towers were NOT a "perfect" top down collapse. Watch the video of tower one for example. Notice that when the obvious destruction begins the destruction it appears to be at about the 96 floor or so with the 12 to 14 stories above them collapse DOWN .. so we see floor 97 "destroyed" and then the the floors above them drop and then the 98th floor is destroyed and the floors above them collapse, then the 99th floor is destroyed and the floors above them collapse... and so on until all those 12-14 floors have been destroyed. AND WE DON'T KNOW HOW THEY WERE DESTROYED. But the top section's bottom seems to be collapsing "into" and spilling over the 96th floor. You can think of the top section as a typical CD where the columns at bottom floor of 14 story building are taken out and the 14 stories collapse down.

THEN and only THEN does the ROOSD top down collapse begin as the mass of those 12-14 floors or what didn't fall over the side... becomes the ROOSD avalanche crushing each successive floor in its path to the ground.

The towers were unique in design and they were "attacked at the top... unlike virtually any building in the world. So they were unique and each saw the same type of assault and likely had the same sort of engineering to assist their collapse. Probabilities have nothing to do with their collapse.

[Kyle Burnett]

Orling cannot present us with one case of TOP DOWN COLLAPSE,
or he would have by now. It is simply his "theory"...ducks or no
ducks, snipes or no snipes.

Wood can't present us with one case of a directed energy device producing effects anything like what happened to the towers either. Hence neither rightly have a theory in the scientific sense, just hypotheses. To rightly be considered a theory would require passing the test of falsification through experimentation, and I'm quite sure both those pushing gravitational collapse and DEW hypotheses will never come anywhere close to accomplishing that.

[James Lewis]

My thoughts exactly. As I said, if Mr. Orling's theories are indeed true, why have we not seen this happen to any other high-rise in the world? Wood's DEW theory has absolutely no basis in fact, much like Mr. Orling's theory. Just show me one instance of another high-rise collapsing in this manner, and I would at least give the benefit of the doubt that it could happen. In the absence of this proof, I must conclude that neither neither theory holds water, because for a theory to work in the real world, one must have proof. I think it's called the scientific method, and last I heard, it works quite well in both the experimental and real worlds.

Orling cannot present us with one case of TOP DOWN COLLAPSE,
or he would have by now. It is simply his "theory"...ducks or no
ducks, snipes or no snipes.

Wood can't present us with one case of a directed energy device producing effects anything like what happened to the towers either. Hence neither rightly have a theory in the scientific sense, just hypotheses. To rightly be considered a theory would require passing the test of falsification through experimentation, and I'm quite sure both those pushing gravitational collapse and DEW hypotheses will never come anywhere close to accomplishing that.

[Jeffrey Orling]

Lewis raises another straw man argument.

I do not present a theory or an hypothesis but present the engineering principles in use every day to design structures.

The strength of materials has been tested and is presented in design load tables. Take out your ASTM steel design manual or even Wood Structural Design data for example and you will find the design loads for various types of steel or wood, sections, connections and so forth. The assembled tabular performance data exists for all building materials and is used to design structures for specific load conditions.

When I design a structure I don't have to test it to see if it will stand and carry the required loads because I base the design on established empirically derived engineering data.

LERA went through a similar process when the designed the towers. However they DID do some wind tunnel testing, which at the time was very new for buildings. It was done to determine if their unconventional approach to wind shear was sound. The wind tunnel test determined that the building moved too much in anticipated wind loads and so visco elastic damping was added to the the truss to facade connection attached to from each truss to every other facade column location.

Further, there were concrete slump tests done as per usual to determine that the concrete mix met designed specs. We don't have the construction logs however showing those test results.

Some of the steel was tested as well, random and destructive testing to determine if it was as per spec. Much of the discussion of how the design loads and materials and systems is in the NIST NCSTAR 1A report and makes interesting reading.

I've stated many times that the twin towers were a very unusual design in that they had their floors constructed in assemblies off site and were very long span with the columns to support one side of the floor slabs also used as the mechanism to resist wind sheer. And the facade was likewise custom fabricated off site.

Further the columns required for the bottom all were custom fabricated box sections of welded plates. There were no rolled section available to support the calculated axial loads. Their design was determined, not by testing them... as it is rather impossible to place a load of 32 million pounds on the sample to see if it would fail. This was the yield strength of core column 501 for example.

The formulas which describe Euler buckling were empirically determined centuries ago and probably a the basis for some experiments in schools. But in the real world Euler's formulas and Young's modulus are used all the time to mathematically test and design structures,

The towers were MOSTLY bolted together as well, but welds are tested as well...

What I have described is basic engineering and is exactly what is predicted for any structure which is over stressed, or over loaded. The key here is that the floor failure was a sub set of the entire structure... and the failure of one floor led to the failure of the identical floor below and then to the columns. Once the load imbalance (excessive) was introduced to the floors.. by redistributing load ONTO them which were formerly carried by the columns... the floors HAD to fail.

The reason why you don't see other high rises come down like this is because presenting such excessive over loading to the upper floors is almost a virtual impossibility under normal circumstances. The destructive load came from the top section of the tower itself as it was somehow destroyed (14 floors in tower 1) and no longer supported by the columns in increments at each floor level, but became an imposed live dynamic load on the upper most intact floor... a live load which was more than 20 times the floor's yield strength.

Go place a ton on every square foot of the top floor of Sears tower and watch all the floors below it collapse exactly as the twin towers.... or any high rise structure for that matter... steel or concrete frame. No heat required what so ever. If you drop the ton on it... its force is multiplied as a dynamic load.

Engineers analyze the performance of structures without physical testing. But they do test complex structures such as autos in destructive testing... or airplanes in wind tunnels.

Absolutely no real need to do physical tests to prove what has been proven about material performance. And scale models will not be reliable. You can't scale all factors in a test such as time or gravity. But if you want to see Euler buckling at work try to assemble a 1/100 scale model of column 501. it will stand 13.6 feet high made of 38 segments that are 4.3 inches tall by .52" x .22 in cross section at the base and H sections which are .14 x .14 made of material which is .01 thick. Place these one atop the other with a dab of glue and see how stable the 13.62' column is. It wont be and it wont be an accurate test of column 501 either. You can't scale model structural failures!

Every time you drive over a suspension bridge consider that it was designed on paper and probably with a slide rule and little or no testing other than noted above.. slump tests and random materials destructive testing. When the engineering is done properly and erected to spec the structure performs as designed under the load conditions EACH component was designed for. If you overload an elevator, you can fail it's cables or car structure etc. but the building it is contained in will NOT fail.

If you overload the top floor of any number of identical spec'd floors and it collapses... all the same floors below will then ALSO collapse when that floor's loads are presented to the ones below. Basic engineering... not a hypothesis or theory.

If you don't accept or understand these basic concepts, you have no business discussing the destruction of a building which came down... came apart and lost its structural integrity. People are only exposing their own ignorance of statics, and engineering by stating that it is impossible for a building such as the twin towers to fail as we observed.

[Jack White]

Orling cannot present us with one case of TOP DOWN COLLAPSE,
or he would have by now. It is simply his "theory"...ducks or no
ducks, snipes or no snipes.

Wood can't present us with one case of a directed energy device producing effects anything like what happened to the towers either. Hence neither rightly have a theory in the scientific sense, just hypotheses. To rightly be considered a theory would require passing the test of falsification through experimentation, and I'm quite sure both those pushing gravitational collapse and DEW hypotheses will never come anywhere close to accomplishing that.

Wood clearly presents theories as theories. Orling presents theories as facts.

Jack

[James Lewis]

Jeffrey...I was just wondering something? Since when did the scientific method become a "straw man"? Engineering principles are one thing, theories are another...but last I checked, the scientific method is tried...true...and once something is proven through it, those results usually stood the test of time. And by the way...did you ever answer Kyle's question about how the towers defied Newton's Third Law?

Lewis raises another straw man argument.

I do not present a theory or an hypothesis but present the engineering principles use every day to design structures.

The strength of materials has been tested and is presented in design load tables. Take out your ASTM steel design manual or even Wood Structural Design data for example and you will find the design loads for various types of steel or wood, sections, connections and so forth. The assembled tabular performance data exists for all building materials and is used to design structures for specific load conditions.

When I design a structure I don't have to test it to see if it will stand and carry the required loads because I base the design on established empirically derived engineering data.

LERA went through a similar process when the designed the towers. However the DID do some wind tunnel testing, which at the time was very new for buildings. It was done to determine of their unconventional approach to wind shear was sound. The wind tunnel test determined that the building moved too much in anticipated wind loads and so visco elastic damping was added to the the truss to facade connection attached to from each truss to every other facade column location.

Further, there were concrete slump tests done as per usual to determine that the concrete mix met designed specs. We don't have the construction logs however showing those test results.

Some of the steel was tested as well, random and destructive testing to determine if it was as per spec. Much of the discussion of how the design loads and materials and systems is in the NIST NCSTAR !a report and makes interesting reading.

I've stated many times that the twin towers were a very unusual design in that they had their floors constructed in assemblies off site and were very long span with the columns to support one side of the floor slabs also used as the mechanism to resist wind sheer. And the facade was likewise custom fabricated off site.

Further the columns required for the bottom all were custom fabricated box sections of welded plates. There were no rolled section available to support the calculated axial loads. Their design was determined, not by testing them... as it is rather impossible to place a load of 32 million pounds on the sample to see if it would fail. This was the yield strength of core column 501 for example.

The formulas which describe Euler buckling were empirically determined centuries ago and probably a the basis for some experiments in schools. But in the real world Euler's formulas and Young's modulus are used all the time to mathematically test and design structures,

The towers were MOSTLY bolted together as well, but welds are tested as well...

What I have described is basic engineering and is exactly what is predicted for any structure which is over stressed, or over loaded. The key here is that the floor failure was a sub set of the entire structure... and the failure of one floor led to the failure of the identical floor below and then to the columns. Once the load imbalance (excessive) was introduced to the floors.. by redistributing load ONTO them which were formerly carried by the columns... the floors HAD to fail.

The reason why you don't see other high rises come down like this is because presenting such excessive over loading to the upper floors is almost a virtual impossibility under normal circumstances. The destructive load came from the top section of the tower itself as it was somehow destroyed (14 floors in tower 1) and no longer supported by the columns but in increments at each floor level, but became an imposed live dynamic load on the upper most intact floor... a live load which was more than 20 times the floor's yield strength.

Go place a ton on every square foot of the top floor of Sears tower and watch all the floors below it collapse exactly as the twin towers.... or any high rise structure for that matter... steel or concrete frame. No heat required what so ever. If you drop the ton it its force is multiplied as a dynamic load.

Engineers analyze the performance of structures without physical testing. But they do test complex structures such as auto in destructive testing... or airplanes in wind tunnels.

Absolutely no real need to do physical tests to prove what has been proven about material performance. And scale models will not be reliable. You can't scale all factors in a test such as time or gravity. But if you want to see Euler buckling at work try to assemble a 1/100 scale model of column 501. it will stand 13.6 feet high made of 38 segments that are 4.3 inches tall by .52" x .22 in cross section at the base and H sections which are .14 x .14 made of material which is .01 thick. Place these one atop the other with a dab of glue and see how stable the 13.62' column is. It wont be and it wont be an accurate test of column 501 either. You can't scale model this structural failures!

Every time you drive over a suspension bridge consider that it was designed on paper and probably with a slide rule and little or no testing other than noted above.. slump tests and random materials destructive testing. When the engineering is done properly and erected to spec the structure performs as designed under the load conditions EACH component was designed for. If you overload an elevator, you can fail it's cables or car structure etc. but the building it is contained in will NOT fail.

If you overload the top floor of any number of identical spec'd floors and it collapses... all the same floors below will then ALSO collapse when that floor's loads are presented to the ones below. Basic engineering... not a hypothesis or theory.

If you don't accept or understand these basic concepts, you have no business discussing the destruction of a building which came down... came apart and lost its structural integrity. People are only exposing their own ignorance of statics, and engineering by stating that it is impossible for a building such as the twin towers to fail as we observed.