THE MANY THEORIES FROM NIST

THE MANY THEORIES FROM NIST/FEMA/ETC

9/11 Theories: Expert vs. Expert
www.youtube.com/watch?v=7ySUrEiVFIM
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1) “PANCAKE THEORY” / “PROGRESSIVE COLLAPSE”

“Like all office buildings, the WTC towers contained a huge volume of air. As they pancaked, all that air–along with the concrete and other debris pulverized by the force of the collapse–was ejected with enormous energy. “When you have a significant portion of a floor collapsing, it’s going to shoot air and concrete dust out the window,” NIST lead investigator Shyam Sunder tells PM. Those clouds of dust may create the impression of a controlled demolition, Sunder adds, “but it is the floor pancaking that leads to that perception.”
http://www.popularmechanics.com/military/a6384/debunking-911-myths-world-trade-center/
———
Debunking Novas Pancake Theory of WTC using common sense
www.youtube.com/watch?v=bdQh18kvpRU

————
WHY THE TOWERS FELL – Transcript
http://www.pbs.org/wgbh/nova/transcripts/2907_wtc.html

“MATTHYS LEVY (Author, Why Buildings Fall Down): As the steel began to soften and melt, the interior core columns began to give. Then you had this sequential failure that took place where it all pancaked—one after the other.

“NARRATOR: This footage shows the process in action. A line of columns in the outer skeleton snaps. The top of the building then lurches outwards and falls. As it does so, it dislodges many more floor trusses. Once the trusses fail, the floors they were holding cascade down with a force too great to be withstood. The result is what’s called a “progressive collapse,” as each floor pancakes down onto the one below.”
———–
“Once one storey collapsed all floors above would have begun to fall. The huge mass of falling structure would gain momentum, crushing the structurally intact floors below, resulting in catastrophic failure of the entire structure. While the columns at say level 50 were designed to carry the static load of 50 floors above, once one floor collapsed and the floors above started to fall, the dynamic load of 50 storeys above is very much greater, and the columns were almost instantly destroyed as each floor progressively “pancaked” to the ground.” – World Trade Center – Some Engineering Aspects, Tim Wilkinson, University of Sydney
http://sydney.edu.au/engineering/civil/wtc.shtml
————–
Reply to NIST
http://gordonssite.tripod.com/id3.html
“NIST lead investigator Shyam Sunder stated, “Those clouds of dust may create the impression of a controlled demolition but it is the floor pancaking that leads to that perception.”
————-

REBUTTAL

There are no stacks of “pancakes” within the rubble. Only sections of the lobby skeleton remains.

Debunking Novas Pancake Theory of WTC using common sense
www.youtube.com/watch?v=bdQh18kvpRU
———–
WTC – NOVA Why The Towers Fell – Another big lie
www.youtube.com/watch?v=JmCEtG2gUCI
————
NOVA | Engineering Ground Zero
www.youtube.com/watch?v=nYPpWhiIXuk
———-
NOVA Says WTC Was Not A Progressive Collapse
www.youtube.com/watch?v=_E7Dpgme200
———–
Pancake Theory Refuted
www.youtube.com/watch?v=9nLg4HlHYTA&
———-

NIST ADMITS PANCAKE THEORY FALSE

NIST admits pancake theory false:
http://sci.tech-archive.net/pdf/Archive/sci.physics/2008-11/msg00627.pdf
———–
Shyam Sunder Admits There Was No Pancake Effect

WTC – collapse revised
www.youtube.com/watch?v=ZHng42BpHDc
www.youtube.com/watch?v=XpfDkL-vFdk

“and we did not see any evidence of pancaking in the videos or photographs we have.” – Shyam Sunder NIST
http://www.pbs.org/wgbh/nova/transcripts/3311_wtc.html
————–
“NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers […] Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.”
– NIST WTC FAQ (question 8)
http://www.nist.gov/el/disasterstudies/wtc/faqs_wtctowers.cfm
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm
————
NIST’s 3-Year $20,000,000 Cover-Up of the Crime of the Century
http://911research.wtc7.net/essays/nist/

“Selling Progressive Collapse

The Report mentions “progressive collapse” 16 times, mostly in sections describing recommendations. It defines progressive collapse as when “a building or portion of a building collapses due to disproportionate spread of an initial local failure” but does not mention how rare the phenomenon is or that there are no examples of total progressive collapse of steel-framed buildings outside of 9/11/01.

By repeatedly invoking the specter of “progressive collapse” while concealing the phenomenon’s lack of repeatability outside of “terrorist incidents,” the Report surreptitiously bolsters its supposition that “global collapse” automatically follows from “collapse initiation.””
————
Finally, an Apology From the National Geographic Channel
http://911review.com/articles/ryan/NationalGeographicApology.html

“Two years later, the National Institute of Standards and Technology (NIST) finally made clear that its “findings do not support the ˜pancake theory’ of collapse.”
———–

EXAMPLES OF PANCAKES COLLAPSE

9/11 Experiment: Concrete evidence. Does it pulverize when falling?
www.youtube.com/watch?v=aa6pyPi386k&

Here is an example of a “Pancake” collapse.
http://www.librariansfor911truth.org/impossiblecollapse.html

CONCLUSION

The “Pancake Theory” is false. There are no stacks of floors.

——————————-

2) “TRUSS PULL IN / PULL OUT THEORY”

“The heat expanded the steel in the truss in all directions. As a result they also expanded into the columns. The trusses/floor system, sagged in the middle because the columns were preventing the trusses from expanding in their direction. That led to the bowing of the exterior columns.”

————-

WTC Pre-Collapse Bowing Debunks 9/11 “Controlled Demolition” Theory
www.representativepress.org/BowingDebunksExplosives.html
www.representativepress.org/BowingDebunksExplosives2.html
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Facts “9/11 Skeptics” don’t want you to see: REAL 911 Truth
www.youtube.com/watch?v=sGAoRrBoPRM
——-
East Face of WTC 2 – 9:21 AM Maximum inward bowing of approx. 10 in.
(18 min after impact)
911motive.tripod.com/WTC2EastFace921.html
——-
South Tower Collapse: Ejected Objects from East Face (Core Columns?)
www.youtube.com/watch?v=0fbk3SoKdIE
————–

REBUTTAL

What’s missing from NIST’s simulation?

Besides the center core, bridging trusses and the steel deck, Nist totally left out the concrete floors! So this whole theory of the “truss Pull in” is totally flawed because the concrete floors would not have “sagged” with the trusses causing this “inward bowing.” The concrete floors would have remained in tact.

NIST WTC-report. What a laugh …
www.youtube.com/watch?v=-RzwmD8uB8g

www.upload.wikimedia.org/wikipedia/commons/8/86/Wtc_floor_truss_system.png
——–
9/11 Skepticism: NIST floor test
www.youtube.com/watch?v=4W37g_uLYNs

NIST’s own tests failed to weaken or melt the WTC steel.
———–
The “Truss Theory”:
A Fantasy Concocted to Conceal a Demolition
http://whatreallyhappened.com/WRHARTICLES/trusstheory.html

The Truss Failure Theory
http://911research.wtc7.net/disinfo/collapse/trusses.html
http://911research.wtc7.net/wtc/analysis/official/trusses.html
——————–
Structural Steel
http://thermalimages.nfshost.com/index.php/Structural_Steel

“11.2.3. How does a fire impact steel connections? Does it affect connections differently than the members themselves?
The connections usually contain more material (additional plates, bolts, etc.) than the connected members. Also, connections often have less exposure to heat and higher capacity for heat dissipation because of their proximity to other members. Therefore, temperatures are likely to develop faster in members than in connections, making connections less critical for fire-protection design.” aisc.org
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Why the NIST WTC Report on the Towers is False
Why the NIST WTC Report on the Towers is False

“Unfortunately, NIST’s report provided only a hypothesis of the events leading up to the initiation of the collapses, or the “collapse initiation sequence.” NIST did not attempt to explain how, once the collapses initiated, the upper sections of these 110-story skyscrapers would continue falling downward through the path of greatest resistance, instead simply asserting that, once each building was destabilized, “global collapse ensued.”

However, we can examine the general features of NIST’s collapse initiation sequence for both Twin Towers to see if it is consistent with known facts, or is at least self-consistent.

The seven steps of NIST’s collapse initiation sequence that are common to both Twin Towers are as follows:[1]

1. A number of columns were severed by aircraft impact
2. Loads were redistributed to the remaining columns
3. Fireproofing was “widely dislodged”
4. Columns and floor assemblies were softened by high temperatures
5. Softened floor assemblies began to sag
6. Sagging floors pulled the exterior columns inward, causing columns to buckle
7. Instability spread around the exterior of the building”
—————
WTC Pre-Collapse Bowing Debunks 9/11 “Controlled Demolition” Theory?
http://911debunkers.blogspot.com/2010/07/wtc-pre-collapse-bowing-debunks-911.html

“1) It is only an initial event, and does not provide any explanation for the global collapse events.
2) Its cause is based purely on speculation. The bowing may have occurred, but there is no evidence that supports that fire alone could have caused this, let alone after only a few minutes of fire.
3) If this was so obvious, why wasn’t it the FIRST theory of collapse and not the THIRD theory of collapse?”
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3) “PILE DRIVER THEORY” (BAZANT AND ZHOU)

“the pile-driver or crush-down theory in which the tops of the Towers act as giant sledgehammers.”

Why Did the World Trade Center Collapse? Simple Analysis
By Zdenˇek P. Baˇzant, Fellow ASCE, and Yong Zhou

Bazant and Zhou were the first people to release their theory as to what happened to the Towers. Take note: Bazant wrote this paper 2 days after 9/11.

Journal of Engineering Mechanics ASCE, in press 9/13/01, Expanded 9/22/01, Appendices 9/28/01
http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf
http://www-math.mit.edu/~bazant/WTC/
http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf
————
“It was as if the top of the building was acting like a huge pile-driver, crashing down on to the floors underneath”
– Chris Wise (quoted by the BBC )
http://news.bbc.co.uk/2/hi/americas/1540044.stm
———–
Mechanics of Progressive Collapse:
Learning from World Trade Center
and Building Demolitions
Zdenek P. Ba • •zant and Mathieu Verdure
http://www.nistreview.org/WTC-PROGRESSIVE-COLLAPSE-BAZANT.pdf
————

REBUTTAL

What Newton has to say about the collapse of WTC
http://infoalternativas.blogspot.ca/2013/04/what-newton-has-to-say-about-collapse.html

———-
Piledriver Theory:
http://911review.com/coverup/fantasy/piledriver.html
http://911research.wtc7.net/disinfo/collapse/piledriver.html
http://911research.wtc7.net/disinfo/experts/articles/bazant_jem/bazant_zhou.html

The Column Failure Theory
http://911research.wtc7.net/disinfo/collapse/columns.html
———–
THE PROGRESSIVE COLLAPSE MECHANICS OF ZDENEK BAZANT
http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=272&MMN_position=529:529
———-
Put up or Shut up: A Year in Review
http://911debunkers.blogspot.ca/2010/04/put-up-or-shut-up-year-in-review.html
———–
NIST Piles it Higher and Deeper: Structural Engineer Anders Björkman Refutes Dr. Zdenek Bazant
http://norcaltruth.org/2010/08/11/nist-piles-it-higher-and-deeper-structural-engineer-anders-bjorkman-refutes-dr-zdenek-bazant/
———-
9/11 Physics: “You Can’t Use Common Sense”
www.youtube.com/watch?v=KDHN1gBkx0M
———-
“The Missing Jolt: A Simple Refutation of the NIST-Bazant Collapse Hypothesis”
by Prof. Graeme MacQueen and Tony Szamboti. Take a look!
http://journalof911studies.com/volume/2008/TheMissingJolt4.pdf
———-
9/11 Experiments: The Arbitrator of Competing Hypotheses
www.youtube.com/watch?v=9YRUso7Nf3s&
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Denying The Obvious – NIST, Bažant and the 9/11 Debunkers
www.youtube.com/watch?v=luGkdBs95kY
———
Andres Bjorkman

NIST piles it higher and deeper: structural engineer Anders Björkman refutes Dr. Zdenek Bazant

NIST piles it higher and deeper: structural engineer Anders Björkman refutes Dr. Zdenek Bazant

1,000,000 Euros Challenge
http://heiwaco.tripod.com/chall.htm

“You are requested to describe a structure where a small top part C can crush the much bigger bottom part A from above, when top part C is dropped by gravity on bottom part A.”

——————
WTC1 Upper Section Collapse
www.youtube.com/watch?v=9wkzkP2FJWY

Still Images:
www.citizenfor911truth.files.wordpress.com/2012/11/wtc1uppersection1.jpg
———–

NOTES: It doesn’t matter what material you use, take a tower of any material and slice it across at three quarters of the way up and try dropping it on the lower piece ~ in no experiment will it ever destroy the whole bottom piece ~ it doesn’t matter if you use bricks, ice, mortar, plastic, egg crates, or even 90 floors of untouched steel and concrete ~ cannot and will never happen!!!

The theory of a smaller weaker block crushing a larger stronger block is IMPOSSIBLE! ~ Therefore the official story can be ELIMINATED!

Keep in mind the Twin Towers were built like pyramids inside structurally! The thickness of the core columns were much thicker at the base and gradually thinner towards the top. The floors could hold 5 times their weight!

Bazant must be a super-genius to understand how two skyscrapers could crush themselves to rubble, a newly observed behavior for steel structures, and write a paper about it in just two days.
—————————————–

4) “HOLLOW STEEL SHAFT” THEORY (CORE DENIAL)

Exposing One Of The 9/11 Commission’s Blatant Lies
www.youtube.com/watch?v=0kW35q0BghM

“the interior core of the buildings was a Hollow steel shaft in which elevators and stairwells were grouped.” – John Farmer (9/11 Commission hearing #13, May 18th, 2004. Pg.541/558)

————
How the World Trade Center fell
http://news.bbc.co.uk/2/hi/americas/1540044.stm

“The protective concrete cladding on the cores would have been no permanent defence in these extraordinary circumstances – keeping the intense heat at bay for only a limited timespan.”
————–
“All the steel was covered in concrete to guarantee firefighters a minimum period of one or two hours in which they could operate – although aviation fuel would have driven the fire to higher-than-normal temperatures. The floors were also concrete.”

Core Denial
“Establishing the true nature of the core structures is of great importance given that the most widely read document on the World Trade Center attack — the 9/11 Commission Report — denies their very existence, claiming the towers’ cores were “hollow steel shaft[s]:”
http://911research.wtc7.net/wtc/arch/core.html
———-
FEMA Figure 2-20 Building performance Study
911research.wtc7.net/wtc/analysis/official/docs/fig_2_20.gif

—————
The Fire-Melts-Steel Idea Was Promoted by Experts
http://911research.wtc7.net/disinfo/collapse/meltdown.html
————–

REBUTTAL

WTC Complex: Over 350,000 Tons of steel (FEMA)
Center Core: 87 by 135 feet (27 by 41m) and contained 47 steel columns running from the bedrock to the top of each tower.

Tower Blueprints:
http://911research.wtc7.net/wtc/evidence/plans/table.html

Building the World Trade Center and Twin Towers
www.youtube.com/watch?v=__gUjUv1vvw

WTC Tower Structural Design Explained:
www.youtube.com/watch?v=MY7BCXew0UI

——————————————

5) “THERMAL EXPANSION” THEORY

NIST WTC 7 Investigation Finds Building Fires Caused Collapse
http://www.nist.gov/public_affairs/releases/wtc-082108.cfm

World Trade Center 7 Report Puts 9/11 Conspiracy Theory to Rest
http://www.popularmechanics.com/technology/engineering/architecture/4278874
“Fire alone brought down the building, the report concludes, pointing to thermal expansion of key structural members as the culprit. The report also raises concerns that other large buildings might be more vulnerable to fire-induced structural failure than previously thought.”

World Trade Center 7 Report Puts 9/11 Conspiracy Theory to Rest
http://www.popularmechanics.com/technology/engineering/architecture/4278874
—————-

REBUTTAL

Fraud Exposed in NIST WTC 7 Reports – Part 2 of 5
http://www1.ae911truth.org/en/faqs/767-fraud-exposed-in-nist-wtc-7-reports-part-2-of-5.html

—————
9/11 Truth and the Collapse of Steel Framed Buildings
http://www.globalresearch.ca/9-11-truth-and-the-collapse-of-steel-framed-buildings/
————-
“Footage That Kills 9/11 Conspiracy Theories” Actually Validates Them”
http://www.ae911truth.org/en/news-section/57-news-releases-by-others/580-footage-that-kills-911-conspiracy-theories-actually-validates-them-.html
————
Thermal Expansion Metals
http://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html
————
Thermal Expansion – Linear
http://www.engineeringtoolbox.com/linear-thermal-expansion-d_1379.html

“When an object is heated or cooled, its length changes by an amount proportional to the original length and the change in temperature.”
———–
EMERGENCY WARNING FOR OFFICE WORKERS (NIST WTC7)
www.youtube.com/watch?v=L7U22m9xLrQ
————-
Why has this new phenomenon of “thermal expansion” never caused another high rise steel framed office fire to collapse?
——————————

6) PRIMARILY DUE TO FIRES

“This was the first known instance of the total collapse of a tall building primarily due to fires” NIST 2008 (Page 37)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=861610

NIST Says WTC7 Collapse Caused By Thermal Expansion, Not Conspiracy
www.youtube.com/watch?v=JfNJJakJJZE

“The collapse of WTC 7 was primarily due to fires.”

————

REBUTTAL

NIST claims Building 7 came down “primarily due to fires” but what does it look like to you?

It was the first time in the history of modern construction that a building totally collapsed from fires of structural damage. Building 7 and both Towers were all controlled demolition.

NIST failed to look at the only possible explanation and did not follow the scientific method.

What Newton has to say about the collapse of WTC
http://infoalternativas.blogspot.ca/2013/04/what-newton-has-to-say-about-collapse.html

————-

7) UNEXPLAINABLE!

NIST: revises theory and admits collapse unexplainable:
http://www.911proof.com/NIST.pdf

“As we mentioned previously, we are unable to provide a full explanation of the total collapse.”
http://www.911proof.com/NIST.pdf
———–

REBUTTAL

This best explains NIST’s position when you are forced to rule out Controlled Demolition. This is why we are demanding a new investigation.
—————————–

OTHERS THEORIES

What caused the World Trade Center towers to collapse on 9/11?
http://www.howstuffworks.com/engineering/structural/cause-world-trade-center-collapse.htm
——–
Why the World Trade Center Towers Fell on September 11
http://architecture.about.com/od/disastersandcollapses/a/twintowerfall.htm
——–
How buildings work
http://www.explainthatstuff.com/howbuildingswork.html
———-
Weak single bolts ‘contributed to WTC collapse’
http://www.smh.com.au/articles/2002/10/27/1035683308803.html

“The single-bolt connections in the framework of the World Trade Center popped and fell apart during the September 11 terrorist attacks, causing the floors to collapse on top of each other, according to a new study.”
———-
30 pictures of 9/11 that show you why you should never forget
http://www.heraldsun.com.au/news/world/pictures-of-911-that-show-you-why-you-should-never-forget/story-fni0xs61-1226717187453

“Engineers say that the World Trade Centers had an unusual design, where much of the structural load was carried by the exterior shell of the building rather than central columns. So when that shell was pierced, the buildings were weakened significantly, precipitating their collapse. Source: Supplied”

www.resources1.news.com.au/images/2013/09/11/1226717/186061-5b3221da-1aa9-11e3-b47b-9923c5873ce4.jpg
————–

THE LEGO THEORY

Charlie Veitch “changing his opinion” about 9/11
www.youtube.com/watch?v=V4i8nBUc2T0
———–
Scientific studies and tests.
www.youtube.com/watch?v=4W37g_uLYNs&
———–

BBC “WHY THE TOWERS FELL”

BBC wrote up their explanation on why the Towers collapsed only 2 days after 9/11. This is a very flawed report that can easily be debunked. So let’s do it. Can you spot the errors and glaring contradictions?

How the World Trade Center fell
http://news.bbc.co.uk/2/hi/americas/1540044.stm

==============================
“The design of the World Trade Center saved thousands of lives by standing for well over an hour after the planes crashed into its twin towers, say structural engineers.”

“The steel and concrete structures performed amazingly well, said John Knapton, professor in structural engineering at Newcastle University, UK.”
—————
Imagine that, they performed “amazingly well” for an hour.
===========================
“Fire reaches 800C- hot enough to melt steel floor supports”

“The columns would have melted, the floors would have melted and eventually they would have collapsed one on top of each other.”
—————-
This is absolutely false. BBC is only 700C short of this happening. lol

~825ºC (1517ºF) – maximum temperature of hydrocarbon fires
~1510ºC (2750ºF) – melting point of typical structural steel.
===========================
“They had a lot of their structure taken out, yet they remained intact for more than an hour, allowing thousands to escape.”
—————-
What structure was taken out other than the outside shell from the impact zones? What about the full intact structure below the impact zones, how were they affected?

“Like a pencil puncturing a screen netting.” WTC Construction manager Frank DeMartini (Died on 9/11. R.I.P.)
==========================
“Temperatures at 800C
But as fires raged in the towers, driven by aviation fuel, the steel cores in each building would have eventually reached 800C – hot enough to start buckling and collapsing.”

“”But steel melts, and 24,000 gallons (91,000 litres) of aviation fluid melted the steel. Nothing is designed or will be designed to withstand that fire.””
————
Again, absolutely false! Jet Fuel burns at a maximum of 260-315C in open air.

Jet Fuel (JET A-1): “Commercial jet fuel is essentially kerosene…”
~260-315°C (500-599°F) – open air burning temperature of JET A-1.
~980°C (1796°F) – maximum burning temperature of JET A-1.
Sources: http://mepetroleum.com/jet_fuel.htm

Even NIST’s owns tests failed to weaken or melt WTC steel.
=========================
“The protective concrete cladding on the cores would have been no permanent defence in these extraordinary circumstances – keeping the intense heat at bay for only a limited timespan.”
—————–
What concrete cladding on the cores?

Center Core: Total center core size was 87 by 135 feet and contained 47 steel box columns (14 x 35” or 22 x 53”) running from the bedrock to the top of each tower.
http://911research.wtc7.net/wtc/arch/core.html

Even if there was this “concrete cladding on the cores”. Concrete has a higher melting point than Steel. The steel in which they forgot to mention.

~1800-2500°C (3272-4532°F) – Melting point of Concrete
=======================

“It was the fire that killed the buildings. There’s nothing on earth that could survive those temperatures with that amount of fuel burning,” said structural engineer Chris Wise.”
——————-
Then why hasn’t fire “killed” any other high rise steel framed building…… EVER.

As for the Jet Fuel. Even FEMA has stated that the Jet Fuel fires did not burn long.

“It is believed that almost all of the jet fuel that remained on the impact floors was consumed in the first few minutes of the fire.” ~ FEMA
=======================
“The buildings’ construction manager, Hyman Brown, agreed that nothing could have saved them from the inferno.”
—————–
What Inferno?
http://www.freewebs.com/california911truth/buildingsfire.jpg
=======================
“”The buildings would have stood had a plane or a force caused by a plane smashed into it,” he said.”
——————
This is correct, they did survive the crash of a Commercial Airliner. Just like they were designed to withstand.

“The WTC towers were in fact the first structures outside of the military and nuclear industries designed to withstand the impact of a jet airplane.”
-Leslie E. Robertson in Reflections on the World Trade Center
National Academy of Engineering, Volume 32, Number 1 – Spring 2002

“We designed the buildings to take the impact of the Boeing 707 hitting the building at any location.” ~ Leslie Robertson

“I designed it for a 707 to hit it,” ~ Leslie Robertson

“I believe the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door, this intense grid, and the jet plane is just a pencil puncturing the screen netting. It really does nothing to the screen netting.” ~ Frank DeMartini
www.youtube.com/watch?v=1pvEge5HPJU
==========================
“Once the steel frame on one floor had melted, it collapsed downwards, inflicting massive forces on the already-weakened floor below.”
—————–
What pre weakened the floors below the impact zones? Last time I checked, fire/heat tends to rise. Like stated above, fire, nor jet fuel can melt steel.
===========================
“Science of collapse
From then on, the collapse became inevitable, as each new falling floor added to the downward forces.”

“”Further down the building, even steel at normal temperatures gave way under the enormous weight – an estimated 100,000 tonnes from the upper floors alone.””

“”It was as if the top of the building was acting like a huge pile-driver, crashing down on to the floors underneath,” said Chris Wise.”
—————–
This defies Newton’s laws of Gravity. The towers came down at near free fall speed with little to no resistance.

Newton’s laws of motion
http://en.wikipedia.org/wiki/Newton’s_laws_of_motion

Newton’s laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces. They have been expressed in several different ways over nearly three centuries,[2] and can be summarized as follows:

First law: The velocity of a body remains constant unless the body is acted upon by an external force.[3][4][5]

Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to the mass m, i.e., F = ma.

Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.
=====================
“The building could have fallen over sideways, he points out, potentially bringing even greater devastation.”
———-
If the Towers toppled over, that probably would have been more believable than a 100,000 ton structure crushing through a 500,000 ton structure at near free fall acceleration.
===================
“Other buildings – including the 47-storey Salomon Brothers building – caved in later, weakened by the earlier collapses, and more nearby buildings may still fall, say engineers.”
————
You mean the same building the BBC reported collapsed 20 minutes before it happened? No other buildings in and around the WTC complex totally collapsed but many of them suffered far more damage and severe fires much worse than Building 7.
===================
“But the eventual collapse of the twin towers was so predictable that the order should have been given to withdraw emergency services within an hour, said Professor Knapton. He watched in horror, knowing the building would fall within two hours.”
————–
Then Knapton is either one of the few people that predicted this or he was given foreknowledge of the eventual collapse. Remember, no building in the history of modern steel framed high rise buildings has ever collapsed.
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“Steel-core design

The building’s design was standard in the 1960s, when construction began on what was then the world’s tallest building. At the heart of the structure was a vertical steel and concrete core, housing lift shafts and stairwells.”
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Actually, the design was not standard. It was the first of it’s kind.

“The towers were designed as “tube in tube” structures, which provided tenants with open floor plans uninterrupted by columns or walls. Numerous, closely spaced perimeter columns provided much of the strength to the structure, along with gravity load shared with the steel box columns of the core. Above the tenth floor, there were 59 perimeter columns along each face of the building, and there were 47 heavier columns in the core. All of the elevators and stairwells were located in the core, leaving a large column-free space between the perimeter that was bridged by prefabricated floor trusses.”
https://en.wikipedia.org/wiki/World_Trade_Center

Again, what concrete core are they talking about?
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“Steel beams radiate outwards and connect with steel uprights, forming the building’s outer wall.”
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A structural engineer would never use the term “beams” to describe the steel in the WTC. They are called COLUMNS!

Perimeter Columns: Each tower had 236 Steel perimeter box columns (14 x 14”) joined together with steel spandrels.
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“All the steel was covered in concrete to guarantee firefighters a minimum period of one or two hours in which they could operate – although aviation fuel would have driven the fire to higher-than-normal temperatures. The floors were also concrete.”
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If concrete covered the steel columns, this would have given the steel extra strength and integrity. As for Jet Fuel, I have shown above that Jet Fuel burns at a much lower temperature than hydro carbon fires.

No mention of the MASSIVE 47 Center Steel Core columns (14 x 35” or 22 x 53”) running from the bedrock to the top of each tower.

Since when did the Towers have a “concrete covering” around the core?
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“Newer skyscrapers are constructed using cheaper methods. But this building was magnificent, say experts, in the face of utterly unpredictable disaster.”
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This closing statement pretty much contradicts the entire article.
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This is the inset photo at the top of the article, it does not come remotely close to the actual design of the WTC.
www.news.bbc.co.uk/olmedia/1540000/images/_1540044_world_trade_structure300.gif
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The core looks like one concrete slab with four steel rebar “beams” that run up the entire building. I wonder how the 99 elevators and the stairwell fit in there.

This is what the Center core looked like:
www.files.abovetopsecret.com/files/img/rx4ef15610.jpg

Here is what the perimeter steel columns looked like:
www.mises.org/community/cfs-filesystemfile.ashx/__key/CommunityServer.Discussions.Components.Files/27/7288.Picture-1.jpg
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Caught up in a conspiracy theory
http://www.bbc.co.uk/blogs/theeditors/2008/10/caught_up_in_a_conspiracy_theo.html
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9/11 Truth Versus The BBC
www.youtube.com/watch?v=LwcL-uQf1mk&
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