I'm going to interrupt Christopher7's WTC7 derail, which is nothing but a repetition of crap.
I took the time to read the paper which the OP touts as "sealing the deal" and decided to respond to it directly since so much attention (complements of the perpetual derail this thread has gotten into) got directed away from the paper this OP was pushing.
I'd like to thank
tfk for his help with this. When I wrote the original draft I asked him him if he could evaluate the content of my response, because many of my "essays" tend to require quite a bit of revision in the wording. And he graciously took the time to read over my response and point out material that needed improvement. So I'd like to make it clear that with out his help it's unlikely that I would have pushed this to an actual response.
Many of the claims that the paper Galileo touts as "sealing the deal" are old, and most of you will be familiar with them. I decided to address them regardless because in my experience with following AE911truth's work this is a good opportunity to point out the standard not just held by Richard Gage but other lesser known members of his group.
Jun 17, 2009
29 Structural & Civil Engineers Cite Evidence for Controlled Explosive Demolition in Collapses of All 3 WTC High-Rises on 9/11
— Gregg Roberts and Staff
>snipped for brevity<
This seals the deal. The experts have spoken.
By enlarge this response follows the paper chronologically. And I addressed statements that relate directly to technical aspects that they push. My original plan was to address some of the political statements but I've decided against doing so because I wanted primarily to focus on the credibility of the claims they make when they use their professional status as leverage. So without further ado, I'll proceed:
WARNING: This will be my longest forum post ever. If you're a TL;DR type of person this will hit you like a brick wall
(1)
Lomba -- “How did the structures collapse in near-symmetrical fashion when the damage was clearly not symmetrical?”
There seems to be a lack of appreciation for how
‘empty’ these buildings were; the toppling behavior that these individuals expect to have happened is impossible. There are two major criteria required in order for anything to topple over:
- The center of gravity must move outside the bottom supports. If the structure was tilted (a block, glass of water, etc) but its center of gravity is not translated sufficiently to fall outside of the bottom contact point it will fall right back to an upright position. If the center of gravity is moved horizontally OUTSIDE of the support point then it will topple.
- A support point has to EXIST. In other words you have to be able to ‘bend’ the building far enough to get the center of gravity displaced that far WITHOUT the building collapsing first. A tilt of about 45 degrees would be required to translate the CG this far outside the outer edge of the building. Think about how the supports would have to react for this to happen; how in which these columns would have to compress and expand for this to happen. The problem was, LONG before the top could tilt that far, the columns below buckled.
The latter of the two conditions described above was impossible for the towers to achieve.
In the case of World Trade Center 7, the fact of the matter is the collapse started internally and moved to the exterior walls. By the time the collapse arrived at the walls the inside of the building was basically gone. The walls fell straight down because they buckled at the bottom. As emphasized, in order to get something to topple to the side, the structure has to be strong enough to support itself. The walls alone were not capable of this. They were given a tiny push to one side or another by the vagaries of the collapsing inner structure. But they basically fell straight down because they buckled down low, and that's the way that gravity pulls.
(2)
The rapidity of collapse – acknowledged by the government as essentially freefall acceleration – was troubling
This in of itself is insufficient to conclude controlled demolition. A building’s fall will be dictated by the same mechanism (gravity) whether the loss of support is intentional or accidental.
The initial claims of freefall acceleration were a consequence of people focusing on the (really) free falling debris that came down like a curtain outside the footprint of the building. These pieces were in free fall, and their contact with the ground was recorded by seismic measurements. Once this egregious error was pointed out, ae911truth and other conspiracy groups started scrambling for anomalies in the fall of the towers.
Very little destruction needs to be done; only the small, light weight connections. Very little energy to break compared to the gravitational energy available. BTW, CDs do
NOT fall at free fall speeds either. They ALSO have to break up the internal structure of the building. Falls are typically at 60% to 80% of free fall. Just like the towers.
(3)
Some note that the fires were weak
We saw no “raging infernos” on TV, David Huebner, P.E., points out. Sooty smoke and dull red flames, Scott says, indicate “cool fires ... fuel-starved fires.”
There are a number of things to consider here:
- Exterior fires are at best an indication of minimum severity. The towers had 43,000 square feet of office space; none of which had the benefit of fire stops to mitigate the spread of fire inside the building.
- Whether a fire is big or small is not determined by the proportion of the structure burning vs the portion that not burning. By that logic a wild fire the size of California wouldn’t be a serious threat since it’s small compared with the United States.
- Smoke is not an indication of the state of a fire. It’s an indication of the efficiency of combustion and the types of fuel which are burning.
- And are you going to see the full interior extent of a multistory fire in a building which had such a dense exterior column grid that the structure looked “windowless” from afar in broad daylight?
There’s also an important engineering lesson to be taken from this; it’s not the ‘weakening’ of the columns from heat that leads to collapse, rather it’s the “plastic creep” of the columns which allowed the geometry to change. This creep can
NOT be given as a function of temperature alone. It is a function of BOTH temperature & stress level.
See
Bazant, Le et al, "What Did and Did Not Cause Collapse of WTC Twin Towers in New York", Journal of Engineering Mechanics ASCE , Vol. 134 (2008).
Note page 2:
"Not really. The initial speculation that very high temperatures were necessary to explain collapse must be now revised since tests revealed a strong temperature effect on the yield strength of the steel used. The tests by NIST (2005, part NCSTAR 1-3D, p. 135, Fig. 6-6) showed that, at temperatures 150° C, 250° C and 350° C, the yield strength of the steel used in the fire stories decreased by 12%, 19% and 25%, respectively. These reductions apply to normal durations of laboratory strength tests (up to several minutes). Since the thermally activated decrease of yield stress is a time-dependent process, the yield strength decrease must have been even greater for the heating durations in the towers, which were of the order of one hour. These effects of heating are further documented by the recent fire tests of Zeng et al. (2003), which showed that structural steel columns under a sustained load of 50% to 70% of their cold strength collapse when heated to 250° C."
Also see UManchester site:
http://www.mace.manchester.ac.uk/pro...es/default.htm
The UManchester site provides data on fire temperatures vs. time for fires with and WITHOUT sprinklers. Recall that the WTC fires were unsprinkled because the impacts destroyed the water mains. Temperatures of unsprinkled fires rise from 1100 - 1300°C. In sprinkled fires, it doesn't get anywhere close to that hot.
(4)
others ask how the tilting upper section of WTC 2 “straightened” itself
In other words why didn’t the collapse continue with the upper block falling over to the side? For the same reasons as explained before; the towers could not achieve it. The angular velocity was trivially slow; it collapsed straight down, rotating very slowly as it did. This didn't change any significant detail of the collapse.
(5)
eyewitness testimony of explosions
Every large fire has reports of explosions. Lots of things explode when exposed to heat. (e.g., car tires, computer monitors, etc.). Heavy things hitting other heavy things sound like explosions. Large, strong structures failing sound like explosions. In simple terms, there is nothing unusual about hearing eye witness reports of explosions.
(6)
unexplained molten iron in the debris pile
Virtually no one who is not a metallurgist or who has not worked in a foundry can distinguish molten iron visually from other molten metals. One of the ways to do this is the "sparklers" that molten iron emits in air. This is the proof that the dripping molten metal from the side of the towers was NOT iron. No sparklers.
As for "molten metal" in the debris, it is a giant barbecue pit. LOTS of fuel; choked back air supply -- ideal conditions for long term burning & heating.
BTW, the
"long term" part is
PROOF POSITIVE that it is not thermite. Thermite contains its own oxygen. Once it starts to fire off, there is no stopping it. It goes. NOW. Therefore, there is
NO WAY that it causes heating for weeks let alone months.
(7)
Many engineers attack implausibilities in the Bažant pile driver model
It’s
very telling when professionals can’t be bothered to actually understand what Bazant’s model was intended to demonstrate. Bazant very clearly states that his model was a simplified representation based on the most ideal conditions for collapse arrest --
conditions which were not in place in the real world collapse.
(8)
Kollar was troubled by the collapses’ “totality and uniformity” and the fact that the mass of debris remained centered on the building core all the way down.
It appears that the working claims in AE911truth are still having trouble deciding whether the towers fell inside or outside their footprint.
(9)
with increasing eccentricity as the collapse progressed,” writes Howard Pasternack, P.E. These systematic collapses required that many structural connections not only fail “nearly simultaneously, But also “in sequential order,” wrote Frank Cullinan, P.E.”
A building collapse is a chaotic event. Those claiming that it didn’t follow their concept of how it
should have happened have a formidable task in front of them in order to lay out a viable claim that their sequence of events is more probable than the observed sequence.
(10)
The engineers find it difficult to believe the government’s claim scattered fires brought about such an orderly collapse.
- In the case of the Twin Towers this claim is outright dishonest.
- In WTC7 -- scattered, UNFOUGHT, UNSPRINKLED, multistory fires in the area of column 79 was all that was required.
(11)
Failure of heat weakened steel would show “large deflection”
For all of these buildings, it is NOT the STRENGTH of the support columns that holds them up. It is the
GEOMETRY of the columns that does. (Well 80% Geometry / 20% strength). The loss of geometry means that they fall.
“Heat weakening” was
not the culprit in the collapse;
viscoelastic creep was. This mechanism led to bending stresses, instead of compressive stresses. Long slender columns can NOT resist bending loads; they buckle.
Only the columns located in the proximity of the impact and fire regions buckled. For the remainder of the collapse the column did not fail through buckling; the connections were broken and the columns were tossed to the side. It is very difficult to distinguish between columns that were bent pre-collapse from those that were bent during the collapse.
(12)
asymmetric and local failure,
People who say this do NOT understand how structures fail.
All global collapses
start with a single point failure. If we asked how all parts of the Challenger "knew" to disassemble at the same instant, then the answer is they didn’t. One FINAL piece failed (burn thru on the O2 tank) led to global destruction.
In the towers thousands of individual pieces failed, however the failure didn’t progress to total collapse because some part was there to take the load of the failed part. However the ability of the structure to tolerate this loss of integrity was progressively shrinking until, finally there was simply ZERO margin left and the whole collapse began.
None of this required any sort of "simultaneous" collapse.
(13)
and slow progress,” David Scott told colleagues at the Institution of Structural Engineers in the UK.
The visible deflection of the exterior panels (18 minutes after impact), the sagging of floor trusses, the gradual worsening of the fire, and the leaning of the tower just prior to collapse initiation don’t count as a progressive deterioration of structural integrity?
(14)
Charles Pegelow. “How could all 47 core columns fail at the same instant?”
All core columns have to be severed at the same time to make such a collapse.
The short answer is that they did not simultaneously fail at the same instant. Some had already failed due to enormous local dynamic out-of-plane load compliments of the air craft impacts. For the remainder of the time the steel was cooking inside a multistory fire. See item
(11) for a complete breakdown of the lead up to collapse initiation.
(15)
Falling objects should take “the path of least resistance,” notes Pasternack, while official explanations claim that Tower debris took the path of greatest resistance – through the strong, crossbraced core structure all the way to the ground.
The path of "least resistance" is
horizontal or
upwards. It's a combination of "which way is gravity pulling" vs. how large deflecting forces can be generated?
An object can ONLY be pushed to the side if its contacting surface can transmit sufficient force to deflect the whole object. In the case of the towers, the forces generated before the tiny connections holding together the lower floors fractured were nowhere near great enough to push the massive upper block to the side.
(16)
NIST states that the jet fuel burned off in just ten minutes
Yes and ignited about 5 or 6 floors simultaneously. That doesn’t happen very often in most office fires. You then have to worry about an acres’ worth of office contents.
Remember, it’s not the lighter fluid in a grill that cooks the hamburgers, it’s the coal. The office contents were the coal and the 10,000 gallons of jet fuel was the lighter fluid.
(17)
Scott points out. “There’s ample evidence that the steel temperatures got nowhere close to the “600+ degrees Centigrade
This of course would be wrong. The temperatures reached between 600 and 800°C; proof being that
every other fire with poor or no insulation performs like this. There is absolutely
no engineering justification for a 700°C temp gradient (1200°C gas temp / 500° C presumed column temp) at the interface between the column & the gasses.
Finally, Bazant has shown that you don't need 600°C to get unlimited, runaway creep.
(18)
Firemen at the 78th-floor impact zone reported “only two small fires,” Scott adds, “not the 1000-degree-Centigrade inferno” government officials claim.
True. On the single, bottom-most floor (a mechanical floor with few combustibles). It says NOTHING about what was on the floors above. It’s important to note by the way, that fires flow UPWARDS.
(19)
Scott notes that several steel-framed towers have burned longer, hotter – and much more intensely without collapse. “As engineers we know what fire can do to steel and what it can’t.”
These buildings were not structurally damaged to begin with and had different structural designs than the Twin Towers. Examining whether or not the buildings which survived serious fires had a concrete core or not is also important to consider given their different material properties in fire.
The physical impact damage that caused BENDING loads on the columns was also critical; fires alone don't cause this kind of loading.
(20)
Rice notes that “perimeter columns weighing several tons each were ejected laterally up to [600] feet. His conclusion: “Not possible without explosives.”
There are all kinds of chaotic collisions that could EASILY explain the horizontal velocity of the beams.
Explosions as "impulse jets" are incredibly inefficient in open air. (That's why you contain it. An IED that is CONTAINED between a tank and the ground can flip the tank. The same explosive set off on the side of the tank will not send the tank flying sideways.
(21)
“[The upper section] began tilting toward the damage zone, and then suddenly dropped straight down
You need a fulcrum to continue a rotational movement. Do you really think these columns and the bolts that connected them were ever meant to support a large section of that building in rotation?
(22)
“No plane hit this building,” points out Graham Inman, a chartered engineer in London.”
What did or did not hit World Trade Center 7 is irrelevant; the unfought, unsprinkled, multistory fires killed the building. It would have collapsed even without the impact damage.
(23)
FEMA’s 2002 inquiry blamed WTC 7’s collapse on fires, though it admits that its “best hypothesis has only a low probability of occurrence.”
This statement is very disingenuous in leaving out the context of FEMA’s statement:
“Although the total diesel fuel on the premises contained massive potential energy, the best hypothesis has only a low probability of occurrence.” source
As can be seen, the context describes FEMA's then working hypothesis fealing with the role of the diesel takes in the fire. Ultimately it was determined that they did not play any role in the building’s collapse.
(24)
Björkman maintains that failures “will always be local and topple the mass above in the direction of the local collapse.”
Bažant’s mathematical model of the upper floors’ transformation into a pile driver “block” free-falling one story to hammer the entire tower into scrap metal and powder involves “very misty allegations – actually inventions,” says Björkman
Never before, Björkman notes, has “a smaller object (the light-weight, upper, actually non-rigid, flexible steel structure consisting of many smaller parts) destroyed the bigger and stronger other object (the complex steel structure below) only with the assistance of gravity.”
Bjorkmans’ errors are too many to count, and nearly every contention he makes collapses under the slightest bit of scrutiny.
(25)
Evidence was not just ignored; it was destroyed
Steel components were stamped with identification numbers that would have aided their reassembly for study
“Why was the steel ... not thoroughly examined by fire-safety and structural experts before being shipped to Asia for recycling?”
Those harping on about not getting enough (or the right) samples do not understand FEMA’s (not NIST’s) materials recovery plan. Their purpose was not to find the particular parts which failed. They knew full well that would be an almost hopeless task, and pointless to boot.
At the time of the material recovery, everyone (with a brain) KNEW the ultimate cause of the collapse. Two jets flew into the buildings, started giant fires, and weakened the structures.
The purpose of the FEMA recovery plan was:
- Find out if the metal met specifications.
- Find out if workmanship mistakes led to failure.
- Get samples of materials so that computer modeling could be done accurately.
The samples that they grabbed were sufficient to do this. Remember, this was the single MOST documented structural failure in history; video from every side, every angle. They had zero doubt that they'd be able to figure out from all of this what had led to the collapse.
Only select parts were identified. A percent of the marked parts were legible.
(26)
Bill Genitsaris, structural engineer and builder based in Melbourne, believes that a pancake-style collapse should have left supporting columns standing. Such a collapse would have left at least dozens of shattered floors in the building footprint below. Only very small floor sections were found, and not many of them.
This is a question of “how tough are the floors vs how much energy was in the falling debris.” There’s no comparison, nothing survived; no desks, no phones, nothing. The collapse was a 200,000 ton mixmaster.
(27)
While NIST fails to show essential work on central issues, its numerous volumes are packed with distracting trivia.
1/100th of what NIST thought about & examined is contained in the report. This is exactly what is true of ALL such reports. You select the most important facts, trying to not overload the reader with trivia. To architecture students like me, and the engineers that I’ve consulted with the NIST did this rather admirably.
(28)
Brookman asked NIST investigators to explain the “complete pulverization of building materials
Once again, early errors.
People initially thought it was concrete that spread in those clouds and for the most part it wasn’t;
it was gypsum. Concrete was broken into large chunks, and then ground down in the turbulence, blender of the collapse. Then it was pulverized when it hit the pavement after a 300 / 500 / 1000 foot fall.
The clouds & (misnamed "pyroclastic flows") were caused by pulverized gypsum, debris and 500 mph winds as 400,000 cubic feet of air was forced out ever 1/10th of a second.
(29)
Obeid rejects the suggestion that one failing column could pull adjacent columns down. “It is not possible for a local failure within the lower structure to spread horizontally,” he wrote recently. “Such a failure would cause a break-away ... instead of pulling the structure with it.”
Nobody has ever suggested that "one column alone failed". Multiple floors failed (in WTC7).
(30)
Obeid says, “the building would not have collapsed so neatly and symmetrically.
The collapse is dictated by the location of the critical failure. By principal this applies to both controlled demolition and failure by accidental means.
(31)
If three modern steel high rises really underwent total progressive collapse in less than two hours of fire, merely because of the fires and some damage to the fireproofing, “we need to understand WHY!”
Steel’s material properties have been well documented over the years and there exists a great deal of literature covering this material, so I’m not sure what’s so difficult to grasp here since the answer this question is obvious.
(32) Scott writes. If WTC 7 failed from a localized fire event, Inman asks, why didn’t the owners and insurers sue the designers?
Building codes drive construction requirements, and WTC7 met them. The building would not have failed due only to a fire with working sprinklers and firefighting efforts.
However, nobody can foresee an event in which a nearby skyscraper collapse completely disables the water mains that supply the sprinklers, scoops out a section of the same building, and ignites fire on multiple floors uncontrolled and left to burn unattended for seven hours.
So from a legal standpoint, the engineers behind the design of WTC7 are simply
not liable for what transpired.
[/end] absolutely long post
That just about covers the material I wanted to respond to. So what does this all mean? Their touting of expertise is essentially moot point. The content of their claims don't stand up to scrutiny, just as has been the case for the last 7 years.
