|#||Study||Comment / Rebuttal (under construction)|
|0||NONE||There are ZERO studies replicating what happened to the concrete and steel World Trade Center buildings - completely collapsing from fire alone, falling at near free fall speed. There should be studies that repeat what happened by experiment.|
|1||Performance based structural fire engineering for modern
Rini, D., Lamont, S. 2008 Proceedings of the 2008 Structures Congress - Structures Congress 2008: Crossing the Borders 314
This non-experimental discussion paper mentions the WTC, but also mentions the Windsor Tower fire in Madrid, which burned much hotter and longer than the WTC and did not collapse.
Engineering perspective of the collapse of WTC-I
Irfanoglu, A., Hoffmann, C.M. 2008 Journal of Performance of Constructed Facilities 22 (1),
|On page 2: "No detailed observational data on the performance of tower core elements exist. Therefore the Purdue research team used finite element simulations to assist in estimating the impact response." A computer simulation is not proof|
Collapse of towers as applied to September 11 events
Cherepanov, G.P. 2008 Materials Science 44 (4), pp. 489-499
|He states "It is proved that progressive collapse is much
slower than free fall."
Truthers agree. Why did the WTCs come down so fast then?
Modeling pre-evacuation delay by occupants in World Trade
Center Towers 1 and 2 on September 11, 2001
Kuligowski, E.D., Mileti, D.S. 2008 Fire Safety Journal
|Modeling only of the evacuation delay, and how people move and behave during emergencies, says nothing about the steel or how collapse occurred|
World Trade Center building disaster: Stimulus for
Kodur, V.K.R. 2008 Indian Concrete Journal 82 (1), pp. 23-31
|In this paper a brief overview of the factors leading to the collapse of the twin towers and WTC 7 is presented.|
"A new era": The limits of engineering expertise in a
Pfatteicher, S.K.A. 2007 International Symposium on Technology and Society, Proceedings, art. no. 4362228
|This is not about the building collapse, and does not deal
with the mechanics.
"Ironically, one lesson reinforced by the fall of the towers is that engineers cannot control the entirety of any engineering project. This reality raises questions about professional responsibility as it relates to risk, vulnerability, and uncertainty. This paper discusses the implications of this new era for engineering practice and education."
|7||Progressive collapse of the World Trade Center: Simple
Seffen, K.A. 2008 Journal of Engineering Mechanics 134 (2), pp. 125-132
Computer model refuted by Dr. Crocket Grabb PhD (Dept Physics, Univ of Iowa) in http://www2.ae911truth.org/docs/Seffenrevpub.pdf
Seffen paper proved ludicrous http://rinf.com/alt-news/911-truth/cambridge-university-twin-towers-theory-debunked/2353/
|9||Scale modeling of the 96th floor of world trade center tower
Wang, M., Chang, P., Quintiere, J., Marshall, A. 2007 Journal of Performance of Constructed Facilities 21 (6), pp. 414-421
They studied a 1/20 scale model of just 1 floor. But the WTCs had over 100 floors, so it didn't model the whole situation.
Students also obtained information reported from the National Institute of Standards and Technology (NIST has been discredited)
|6||A collective undergraduate class project reconstructing the
September 11, 2001 world trade center fire
Marshall, A., Quintiere, J. 2007 ASEE Annual Conference and Exposition, Conference Proceedings
|Same as the 1 floor study - irrelevant|
|10||Failure of welded floor truss connections from the exterior wall during collapse of the world trade center towers http://www.aws.org/wj/supplement/WJ_2007_09_s263.pdf PDF Banovic, S.W., Siewert, T.A. 2007 Welding Journal (Miami, Fla) 86 (9), pp. 263-s-272-s||Proves
the Truther point.
"Exposure to fires prior to the collapse was not found to have an effect on the failure mode of the floor truss connections"
No fire could do it, so it took explosives.
|11||The collapse of the world trade center towers: A
Gayle, F.W. 2007 MRS Bulletin 32 (9), pp. 710-716
|Author Frank W. Gayle (email@example.com ) is a NIST employee, a discredited source on the topic of 9/11. Of course he will lie.|
|12||Building code changes reflect world trade center
Hansen, B. 2007 Civil Engineering 77 (9), pp. 22+24-25
many codes changed much at all!
The building codes were already sufficient - except for controlled demolition
|13||Fire load in a steel building design
Razdolsky, L. 2008 Proceedings of the 4th International Structural Engineering and Construction Conference, ISEC-4 - Innovations in Structural Engineering and Construction 2, pp. 1163-1167 http://reopen911.info/Archi-Inge/
|Showed how fire alone could not explain the collapse. _|
|14||The structural steel of the World Trade Center towers
Gayle, F.W., Banovic, S.W., Foecke, T., Fields, R.J., Luecke, W.E., McColskey, J.D., McCown, C., Siewert, T.A. 2006 Journal of Failure Analysis and Prevention 6 (5), pp. 5-8
|Neither high-rate tests nor recovered components gave any evidence of brittle failure. The high-temperature mechanical properties, necessary for modeling the response to the fires, were consistent with other construction steels.|
|15||Progressive collapse of structures: Annotated bibliography and comparison of
codes and standards
Mohamed, O.A. 2006 Journal of Performance of Constructed Facilities 20 (4), art. no. 001604QCF, pp. 418-425
States that there are no buildings that have collapsed like the WTCs
Progressive collapse is one of the most under-researched areas in structural engineering due to the relative scarcity of the circumstances leading to progressive collapse
|16||A simple model of the World Trade Center fireball dynamics
Baum, H.R., Rehm, R.G., Quintiere, J.G. 2005 Proceedings of the Combustion Institute 30 II, pp. 2247-2254
A simple model of the fireball produced by the initial impact, and acknowledges that the fireball burned out soon after. But it stops there, and does not cover what happened about 1 hour later.
|17||Impact of the Boeing 767 Aircraft into the World Trade Center
Karim, M.R., Hoo Fatt, M.S. 2005 Journal of Engineering Mechanics 131 (10), pp. 1066-1072
A numerical simulation of the aircraft impact into the exterior columns of the World Trade Center (WTC) was done using LS-DYNA. For simplification, the fuselage was modeled as a thin-walled cylinder, the wings were modeled as box beams with a fuel pocket, and the engines were represented as rigid cylinders.
|Author found that the jet would have
to travel very fast, just to penetrate the exterior columns, where it lost
45% of its energy, much less the interior ones.
The minimum impact velocity of the aircraft to just penetrate the exterior columns would be 130 m/s (290 miles per hour). It was also found that a Boeing 767 traveling at top speed would not penetrate exterior columns of the WTC if the columns were thicker than 20 mm.
|18||High-fidelity simulation of large-scale structures
Hoffmann, C., Sameh, A., Grama, A. 2005 Lecture Notes in Computer Science 3515 (II), pp. 664-671 http://link.springer.com/chapter/10.1007%2F11428848_86#page-1
Computer simulation cartoons prove nothing
"We also aim to perform a high-fidelity simulation of the tragic World Trade Center (WTC) crash."
|19||Collapses of the world trade center towers
[No author name available] 2005 Indian Concrete Journal 79 (8), pp. 11-16
|20||Industry updates: Fireproofing, staircases cited in World Trade Center report
[No author name available] 2005 Journal of Failure Analysis and Prevention 5 (4), pp. 34
only mentioned in passing
Does not support the BS911
|21||September 11 and fracture mechanics - A retrospective
Cherepanov, G.P. 2005 International Journal of Fracture 132 (2), pp. L25-L26
|The present letter advances
the concept of self-sustaining fracture--or, shorter,the
self-destruction--the concept introduced in the author’s book, as the
mechanism and cause of the large scale destruction of the World Trade Center
on September 11, 2001. When initiated, this type of fracture, specific for
The WTC towers were not overstressed at the time of collapse. They were built to withstand a plane impact and did so very well.
|22||Structural responses of World Trade Center under aircraft attacks
Omika, Y., Fukuzawa, E., Koshika, N., Morikawa, H., Fukuda, R. 2005 Journal of Structural Engineering 131 (1), pp. 6-15 http://cedb.asce.org/cgi/WWWdisplay.cgi?144571
|At the September 11, 2001,
terrorist attacks on the New York World Trade Center (WTC) Towers, extensive
structural damage, including localized collapse, occurred at several floor
levels directly impacted by the aircraft. Despite this massive localized
damage, each structure remained standing for approximately 1 h or 1 h 30
min. Although the damage to the beams and columns in the perimeter tube
of each tower were clarified in the published ASCE/FEMA report, the damage
to the floor system and inner core columns were not estimated. The purpose
of this study is to determine why the towers remained standing after impact
through several analytical studies, including impact analyses using a
simplified model to estimate the overall damage, a rigorous finite element
model to estimate the local damage, and stress analyses after some
structural members are lost. The results of the stress analyses show why
both buildings did not collapse immediately after impact, and WTC2
collapsed sooner than WTC1
The WTC towers were designed to withstand plane impact, that is why.
|23||Impact of the 2001 World Trade Center attack on critical interdependent
Mendonça, D., Lee II, E.E., Wallace, W.A. 2004 Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics 5, pp. 4053-4058
|This work catalogues and
analyzes reports of impacts to interdependent infrastructure systems
associated with the 2001 World Trade Center attack. The results suggest that
there were impacts to various types of interdependencies among nearly all
critical infrastructure systems. Moreover, impacts continued to be reported
throughout the one hundred day period following the attack. The paper
concludes with a discussion of possible strategies for improving
understanding of infrastructure interdependencies and for managing them
during an emergency response.
This paper says nothing to refute the possibility of explosives. Yes the explosives impacted various types of interdependencies and critical infrastructure systems. That's why we need a new 9/11 investigation.
|24||Use of high-efficiency energy absorbing device to arrest progressive collapse of
Zhou, Q., Yu, T.X. 2004 Journal of Engineering Mechanics 130 (10), pp. 1177-1187
Trade Center collapse has brought attention to progressive collapse of tall
buildings and the study of possible countermeasures. From the viewpoint of
energy transfer, this analysis explains why the collapse could not stop by
itself once began. By introducing a design parameter called collapse
stability index that controls design against progressive collapse, it is
found that conventional design of a tall building usually leads to an
inherently unstable structure in the event of a progressive collapse. In a
subsequent feasibility study in this paper, a heavy-duty metal-based
honeycomb energy absorbing structure is proposed. Using a finite element
analysis, it is demonstrated that the structure is capable of absorbing
potential energy released in a tall building collapse. The added energy
absorbing devices will only occupy a small percentage of the total floor
space. By properly designing and installing such devices, a progressive
collapse, should it happen in a tall building, may be arrested within a few
floors, and hence, the building is inherently stable to the progressive
collapse. The theory is also elaborated with the example of the World Trade
So they have a theory of how honeycombed structures would be stronger. Let's see them build one and test it. The paper assumes, without proof, that the WTC was not already strong enough, as they survived for about 1 hour after the plane crash.
|25||Progressive analysis procedure for progressive collapse
Marjanishvili, S.M. 2004 Journal of Performance of Constructed Facilities 18 (2), pp. 79-85
collapse of the World Trade Center towers in September 2001, there has been
heightened interest among building owners and government entities in
evaluating the progressive collapse potential of existing buildings and in
designing new buildings to resist this type of collapse. The General
Services Administration and Department of Defense have issued general
guidelines for evaluating a building’s progressive collapse potential.
However, little detailed information is available to enable engineers to
confidently perform a systematic progressive collapse analysis satisfying
these guidelines. In this paper, we present four successively more
sophisticated analysis procedures for evaluating the progressive collapse
hazard: linear-elastic static; nonlinear static; linear-elastic dynamic; and
nonlinear dynamic. We discuss the advantages and disadvantages of each
method. We conclude that the most effective analysis procedure for
progressive collapse evaluation incorporates the advantageous parts of all
four procedures by systematically applying increasingly comprehensive
analysis procedures to confirm that the possibility of progressive collapse
Says nothing to refute the possibility of explosives - just talks about different methods of analyzing a collapse. So what?
|26||Lessons learned on improving resistance of buildings to terrorist attacks
Corley, W.G. 2004 Journal of Performance of Constructed Facilities 18 (2), pp. 68-78
presents some findings of the FEMA and SEI/ASCE sponsored studies of
structural performance of New York’s World Trade Center (WTC) following the
attacks of September 11, 2001, and the Murrah Building following the April
19, 1995, Oklahoma City bombing. The WTC collapses were caused not by
aircraft impact alone but by the combination of impact and the resulting
fire that weakened structural members and connections. On the other hand,
the Murrah Building collapsed as a direct result of the blast. Although
these studies call for further research in a number of areas, this report
summarizes some of the lessons learned.
Corley simply says buildings should be stronger. But the WTC towers were strong enough - except for explosives.
|27||Anatomy of a disaster: A structural investigation of the World Trade Center
Abboud, N., Levy, M., Tennant, D., Mould, J., Levine, H., King, S., Ekwueme, C., (...), Hart, G. 2003 Forensic Engineering, Proceedings of the Congress, pp. 360-370
|The purpose of
this study is to analyze the damage to the structure of each of the WTC Twin
Towers due to the high speed impacts of the Boeing 767 airplanes and
subsequent fires in order to understand why the Twin Towers stood for as
long as they did, and why they ultimately collapsed. The Boeing 767
airplane attacks on WTC 1 and WTC 2 caused immediate and significant
structural damage to the towers: In each case, exterior columns were severed
and the floor system at the point of impact was damaged. The airplanes broke
up during the impact and the resulting projectiles and fragments proceeded
to inflict further damage to the cores. Much of the impact damage to the
exterior walls of the towers was evident. However, damage to the
interiors was not visible and cannot be quantified on the basis of the
physical evidence. Dynamic nonlinear explicit finite element FLEX
simulations coupled with independently validated airplane crash models were
leveraged to understand and assess the structural states of damage to the
tower interiors that could not be observed; this includes the degradation or
loss of the load carrying capacity of columns and floor assemblies as well
as the stripping of fireproofing from structural members. The impact damage
to the structures was substantial but so were their reserve capacity and
redundancy. Iterative analyses of the load redistribution in the impact
damaged towers clearly indicate that the outer tube structures were very
effective in developing Vierendeel action around the severed exterior
columns and that the outrigger hat trusses provided a substantial redundant
load path away from the damaged core columns, thus delaying the eventual
collapses of the towers. These analyses also indicate that the damage to the
corner of the core in WTC 2 left it in a state more vulnerable to subsequent
thermal loads compared to WTC 1. This eccentric damage, more than the height
of the airplane impact, resulted in a shorter time to collapse for WTC 2,
considering that the estimated fire environments in both towers were not
The authors are puzzled why the WTC towers collapses, proving Truther point. They say they could not analyze the core because it as not visible, then say it "indicates" the damage to the core made it vulnerable.
|28||World Trade Center disaster: Damage/debris assessment
Thater, G.G., Panariello, G.F., Cuoco, D.A. 2003 Forensic Engineering, Proceedings of the Congress, pp. 383-392
(LZA) was retained on behalf of Silverstein Properties, a lease-holder of
the World Trade Center (WTC) site, to perform structural investigative
services in connection with the World Trade Center attacks. Our work
included a review of all relevant available photographic evidence (still
photos and video) and utilization of the knowledge LZA gleaned through our
continual site observations from September 11, 2001 through July 2002, as
the New York City Department of Design and Construction's lead engineering
consultant. This paper summarizes LZA's evaluation of the following: 1)
Structural damage sustained by the exterior frames of WTC 1 and WTC 2 due to
the aircraft impacts, 2) Debris distribution resulting from the collapses of
WTC 1 and WTC 2. This includes an assessment of which tower's debris damaged
the remaining World Trade Center buildings and other nearby buildings, and
3) Structural damage sustained by WTC 1 due to the collapse of WTC 2.
What do you expect a study funded by Larry Silverstein, a suspect in the mass murder and insurance fraud, would find?
|29||How did the WTC towers collapse: A new theory
Usmani, A.S., Chung, Y.C., Torero, J.L. 2003 Fire Safety Journal 38 (6), pp. 501-533
|This paper uses a finite
element model to investigate the stability of the Twin-Towers
of the World Trade Center, New York for a number of different fire
scenarios. This investigation does not take into account the structural
damage caused by the terrorist attack. However the fire scenarios included
are based upon the likely fires that could have occurred as a result of the
attack. A number of different explanations of how and why the Towers
collapsed have appeared since the event. None of these however have
adequately focused on the most important issue, namely ‘what structural
mechanisms led to the state which triggered the collapse’. Also, quite
predictably, there are significant and fundamental differences in the
explanations of the WTC collapses on offer so far. A complete consensus on
any detailed explanation of the definitive causes and mechanisms of the
collapse of these structures
is well nigh impossible given the enormous uncertainties in key data (nature of the fires, damage to fire protection, heat transfer to structural members and nature and extent of structural damage for instance). There is however a consensus of sorts that the fires that burned in the structures after the attack had a big part to play in this collapse. The question is how big? Taking this to the extreme, this paper poses the hypothetical question, “had there been no structural damage would the structure have survived fires of a similar magnitude”?
A robust but simple computational and theoretical analysis has been carried out to answer this question. Robust because no gross assumptions have been made and varying important parameters over a wide range shows consistent behaviour supporting the overall conclusions. Simple because all results presented can be checked by any structural engineer either theoretically or using widely available structural analysis software tools. The results are illuminating and show that the structural system adopted for the Twin-Towers may have been unusually vulnerable to a major fire. The analysis results show a simple but unmistakable collapse mechanism that owes as much (or more) to the geometric thermal expansion effects as it does to the material effects of loss of strength and stiffness. The collapse mechanism discovered is a simple stability failure directly related to the effect of heating (fire). Additionally, the mechanism is not dependent upon failure of structural connections
Just a bunch of theories. How about considering explosives?
|30||Microstructural analysis of the steels from Buildings 7, & 1 or 2 from the World
Biederman, R.R., Sullivan, E.M., Sisson Jr., R.D., Vander Voort, G.F. 2003 Microscopy and Microanalysis 9 (SUPPL. 2), pp. 550-551
abstract available - just says a paper was submitted.
Article costs $45 to read
"WTC: Lightweight Steel and High-Rise Buildings"
Fire Engineering v.155, no. 4, (2002): 145-150.
probably resembles a hard drive that is heavily loaded and has not been
defragged. A number of people have said they'd like to pick my brain about
the World Trade Center (WTC) and high-rise buildings in general. Here are
This is not a scientific article. His "pickings"?
He only mentions WTC in a few sentences.
|32||Analysis of the thermal exposure in the impact areas of the World Trade Center
Beyler, C., White, D., Peatross, M., Trellis, J., Li, S., Luers, A., Hopkins, D. 2003 Forensic Engineering, Proceedings of the Congress, pp. 371-382
of each tower was caused by extensive damage resulting from the aircraft
impact to each tower and subsequent weakening of the steel at the impact
zone by heating of unprotected steel by fire. While the fire was massive in
spatial extent, the thermal environment created by the fire was
significantly less severe than normally occurs in fully developed
compartment fires. The spray applied fireproofing was removed from
structural members directly exposed to the impact debris field. The heating
of the unprotected columns resulted in the loss of structural capacity and
ultimately resulted in the collapse of the towers. The collapse mechanisms
for the two towers were different as a result of the differing impact
dynamics rather than differences in fire dynamics.
Paper admits the fire was not significantly more than on other buildings that survived. So explosives had to make the difference.
|33||Clifton, Charles G.
Elaboration on Aspects of the Postulated Collapse of the World Trade Centre Twin Towers
HERA: Innovation in Metals. 2001. 13 December 2001.
|34||"Construction and Collapse Factors"
Fire Engineering v.155, no. 10, (2002): 106-108.
|The FEMA study indicates that
the transmission tower on the top of the North Tower began to move downward
before there was any movement in the exterior wall. This would indicate that
collapses in the North Tower began with structural failures in the center
core of the building.
Yes, with explosives planted by Ace Elevator Company
Fire Engineering eagerly awaits more in-depth and detailed analyses of the collapse from the upcoming study by the National Institute of Standards and Technology.
Yes, NIST admitted there was free fall for 8 floors
|35||Zdenek P. Bazant, Yong Zhou - Why Did the World Trade Center
Collapse?—Simple Analysis - Journal of Engineering Mechanics (Vol. 128, No.
1) - 2002/01
Zdenek P. Bazant, Yong Zhou - Addendum to "Why Did the World Trade Center Collapse?—Simple Analysis"- Journal of Engineering Mechanics (Vol. 128, No. 3) - 2002/03
|Bazant's "King Kong" fallacy of a "pile driver"
thoroughly debunked by
The Missing Jolt: A Simple Refutation of the NIST-Bazant Collapse Hypothesis
"Learning and Applying the Lessons of the WTC Disaster"
Fire Engineering v.155, no. 10, (2002.): 133-135.
|As the scope of the World
Trade Center (WTC) tragedy came into focus in the hours following the
attacks, I wondered what happened to the towers. Why did they come down so
Glenn agrees that it was odd.
I thought that a comprehensive investigation would soon be under way—a master plan, multiple teams of investigators, an army of specialists documenting the scene and securing the evidence. Unfortunately, I was very wrong.
Glenn agrees that the WTC was not investigated properly
Certain aspects of the disaster, such as the evacuation, weren't being examined at all by any official organization.
Yes, Glenn, we need a real investigation.
|37||"Dissecting the Collapses"
Civil Engineering ASCE v. 72, no. 5, (2002): 36-46.
This is not an experimental study, but
simply a re-cap of the Official Story.
|38||Thomas W. Eagar, Christopher Musso
"Why Did the World Trade Center Collapse? Science, Engineering, and Speculation"
JOM v. 53, no. 12, (2001): 8-12. 2001/12
Journal of Materials (JOM)
The Minerals, Metals & Materials Society
|They begin by doubting the Official
There have been numerous reports detailing the cause of the World Trade Center Tower collapse on September 11, 2001....however, simple quantitative analyses show that some common conclusions are incorrect; for example, the steel could not melt in these flames and there was more structural damage than merely softening of the steel at elevated temperatures.
Truthers totally agree
The fire is the most misunderstood part of the WTC collapse. Even today, the media report (and many scientists believe) that the steel melted. It is argued that the jet fuel burns very hot, especially with so much fuel present. This is not true.
It is easier to accept natural or unintentional tragedies; it is the intentional loss of life that makes us fear that some people have lost their humanity.
|39||World Trade Center Building Performance Study: Data Collection, Preliminary
Observations, and Recommendations
Federal Emergency Management Agency and the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE) , Therese McAllister, report editor.
is a report by FEMA which reports to Bush. Mostly it is a recap
of how the buildings were constructed. What do you expect it to have?
WTC 7 page 5-16: The extent and severity of the resulting damage to WTC 7 are currently unknown.
It does not appear that the collapse of WTC 1 affected the roof, or the east, west, and north elevations of WTC 7 in any significant way.
Thanks FEMA. We agree.
|40||Gabrielson, T.B., Poese, M.E., & Atchley, A.A.
"Acoustic and Vibration Background Noise in the Collapsed Structure of the World Trade Center"
The Journal of Acoustical Society of America v. 113, no. 1, (2003): 45-48.
of acoustic and vibration background noise were made on 18 September 2001 at
the southern edge of the World Trade Center collapse. Sensors were deployed
in a configuration reasonable for survivor search and near an on-going
recovery operation and heavy debris removal. Geophones were placed on steel
beams that extended into a deep void and a microphone was lowered below
ground level into a pocket in the rubble. Even in what appeared at ground
level to be a high-noise environment, weak or distant taps and bangs
generated either by the authors or by recovery personnel produced distinct
signals from the microphone and geophones.
So they measured some ground vibrations a week after 9/11. So what?
Fire Engineering v. 155, no. 10, (2002): 97-103
"TMS Hot Topic Symposium Examines WTC Collapse and Building Engineering"
JOM, v. 54, no. 4, (2002): 13-17.
"World Trade Center Collapse-Civil Engineering Considerations"
Practice Periodical on Structural Design and Construction v. 7, no. 3, (2002): 134-135.
|44||Newland, D.E., & Cebon, D.
"Could the World Trade Center Have Been Modified to Prevent Its Collapse?"
Journal of Engineering Mechanics v. 128, no. 7, (2002):795-800.
|45||National Institute of Standards and Technology: Congressional and Legislative
“Learning from 9/11: Understanding the Collapse of the World Trade Center”
Statement of Dr. Arden L. Bement, Jr., before Committee of Science House of Representatives, United States Congress on March 6, 2002.
|NIST originally tried to hide the fact that free fall occurred. Only on protest from the public, including high school physics teacher David Chandler, did NIST finally agree that free fall occurred for about 8 floors. Thus there must have been explosives involved. So how reliable can this NIST report be?|
|46||Pinsker, Lisa, M.
"Applying Geology at the World Trade Center Site"
Geotimes v. 46, no. 11, (2001).
The print copy has 3-D images.
|47||Public Broadcasting Station (PBS)
Why the Towers Fell: A Companion Website to the Television Documentary.
NOVA (Science Programming On Air and Online)
|Computer cartoon simulation shows "pancaking" but shows the
central core still standing, but it was not.
NOVA/PBS includes includes Matthys Levy, CEO of CE firm, Author of "Why Buildings Fall Down" saying "It was very much like a controlled demolition when you look at it because the building essentially fell almost vertically down as if someone had deliberately set blasts to take place to cause the building to fall vertically downward."
http://www.youtube.com/watch?v=jwsBkZhP_0c at 8:30 minutes
Jonathan Barnet, Professor of Fire Protection Engineering says: "Until 9/11, I was unaware of any protected steel structure that had collapsed, anywhere in the world, from just the fire." http://www.youtube.com/watch?v=Aw7e2VkuSrk&feature=related 3:00 minute
Brian Clark, who escaped said that as
he decended "see flames just licking up,
not a roaring inferno, just quiet flames."
"No Code Changes Recommended in World Trade Center Report"
ENR v. 248, no. 14, (2002): 14.
|There are no changes recommended because the Code was already very good. The only change could be that buildings must now be able to withstand explosives.|
"Study Absolves Twin Tower Trusses, Fireproofing"
Engineering News-Record (ENR) v. 249, no. 19, (2002): 12-14.
Agreed! 9/11 Truth says the collapsed was by explosives, not weakening
trusses or lost fireproofing. Thank you for proving our point!
"Failure of the floors...was shown not to have had any significant role in the initiation of the collapses," says the report.
The report also exonerates the steel's sprayed-on fireproofing.
"The buildings were well-designed, rugged and withstood a tremendous impact,"
The Weidlinger-led study was commissioned by Silverstein Properties Inc. (Silverstein is a suspect in the mass murder.)
|50||The University of Sydney, Department of Civil Engineering
World Trade Center - Some Engineering Aspects
A resource site.
|51||"WTC Engineers Credit Design in Saving Thousands of Lives"
Engineering News-Record (ENR) v. 247, no. 16, (2001): 12.
|Yes the WTC was designed to withstand a jet hitting it, and it did for about an hour for each tower. There was no reason that a cooling, and strengthening, structure would fail to hold up, as it had for over 30 years. Engineers always construct buildings not to collapse.|
|52||Effect of fire on composite long span truss floor systems, Graeme Flint, Asif Usmani, Susan Lamont, Jose Torero and Barbara Lane, "Journal of Constructional Steel Research", Volume 62, Issue 4, April 2006, Pages 303-315|
|53||Structural Response of Tall Buildings to Multiple Floor Fires, Graeme Flint, Asif Usmani, Susan Lamont, Barbara Lane, and Jose Torero, "Journal of Structural Engineering", Volume 133, Issue 12, December 2007, Pages 1719-1732|
|54||National Institute of Standards and Technology (NIST) - Federal Building and Fire Safety Investigation of the World Trade Center Disaster -2005/09||
Scientists, Scholars, Architects & Engineers respond to NIST
By 16 scientists, scholars, architects, and engineers
High-Fidelity Visualization of Large-Scale Simulations -
|The title says it all. This is just a visualization which can be programmed to show anything, even the WTC dancing.|
Seismic data were recorded at the
Lamont-Doherty Earth Observatory (LDEO) of Columbia University
|When the WTCs were falling, it was not producing significant seismic data. The force was absorbed by the floors below. Only near the bottom, when the rubble started impacting the ground, producing detectable seismic signals. Explosions in the air do not produce significant seismic data.
However, signals were received just prior to the jet impact on WTC 1 caused by explosions in the basement.
William Rodriguez and others personally experienced explosions from below "a few seconds" prior to jet impact.
Columbia and Protect support (unintentionally) the hypothesis of Controlled Demolition.
Columbia reports vibrations from the seismograms at LCSN Station in Palisades NY.
08:46:26 vibration for a Richter scale of .9 for 12 seconds
08:46:30 NIST's video evidence, using Air Traffic Control data, NTSB analysis, and infrared satellite data.
Evidently there was an explosion about 4 seconds prior to the first jet's impact , indicating the presence of pre-planted explosives.
|57||Protec was engaged in vibration monitoring activies on private construction sites in Manhattan on 9/11 with portable seismographs.||thermalimages.nfshost.com/index.php/World_Trade_Center_Seismic_Signal
|58||2002/05 - Massachusetts Institute of Technology (MIT) - The Towers Lost and Beyond - link|
2002/09 - John D. Osteraas - World Trade Center: Assessment of Structural and
The study was conducted for Exponent Failure Analysis Associates on behalf of Swiss Re and other insurers of the WTC complex.
2002/09 - Ali Reza - Damage to the WTC Complex Due to the Collapse of Only One
The study was conducted for Exponent Failure Analysis Associates on behalf of Swiss Re and other insurers of the WTC complex.
2002/10 - Weidlinger Associates Inc. (WAI), LZA Technology/Thornton-Tomasetti,
ARUPFire, Hughes Associates Inc., Hillman Environmental Group, RWDI, Z-Axis Corp
- World Trade Center—Structural Engineering Investigation -link
The study was performed by a group of engineering firms led by WAI and was conducted on behalf of Silverstein Properties.
|Larry Silverstein is a suspect in the murder of thousands of his tenants, for the insurance money. So any study funded by him would be highly suspect.|
|62||2008/10 - Zdenek P. Bazant, Jia-Liang Le, Frank R. Greening, David B. Benson -
What Did and Did not Cause Collapse of WTC Twin Towers in New York - Journal of
Engineering Mechanics (Vol. 134, No. 10) - full article
|Previous analysis of progressive collapse
showed that gravity alone suffices to explain the overall collapse of the
World Trade Center Towers. However, it remains to be determined whether the
recent allegations of controlled demolition have any scientific merit. The
present analysis proves that they do not. The video record available for the
first few seconds of collapse is shown to agree with the motion history
calculated from the differential equation of progressive collapse but,
despite uncertain values of some parameters, it is totally out of range of
the free fall hypothesis, on which these allegations rest. It is shown that
the observed size range (0.01 — 0.1 mm) of the dust particles of pulverized
concrete is consistent with the theory of comminution caused by impact, and
that less than 10% of the total gravitational energy, converted to kinetic
energy, sufficed to produce this dust (whereas, more than 150 t of TNT per
tower would have to be installed, into many small holes drilled into
concrete, to produce the same pulverization). The air ejected from the
building by gravitational collapse must have attained, near the ground, the
speed of almost 500 miles per hour (or 223 m/s, or 803 km/h) on average, and
fluctuations must have reached the speed of sound. This explains the loud
booms and wide spreading of pulverized concrete and other fragments, and
shows that the lower margin of the dust cloud could not have coincided with
the crushing front. The resisting upward forces due to pulverization and to
ejection of air, dust, and solid fragments, neglected in previous studies,
are indeed found to be negligible during the first few seconds of collapse
but not insignificant near the end of crush-down. The calculated crush-down
duration is found to match a logical interpretation of seismic record, while
the free fall duration grossly disagrees with this record.
This was debunked. Air cannot achieve 500 mph if the material pushing it is not going even half that speed. Dr. Greening abandoned Bazant and joined the Truther movement.
A Bibliography Of Scientific Literature On The World Trade Center Collapse
Studies And Investigations (all are above)
2002/07 - David E. Newland, David Cebon - Could the world trade center have been modified to prevent its collapse? - Journal of Engineering Mechanics (Vol. 128, No. 7)
2002/08 - Bernard Monahan - World Trade Center Collapse—Civil Engineering Considerations - Practice Periodical On Structural Design And Construction (Vol. 7, No. 3)
2002/10 - James G. Quintiere, Marino di Marzo, Rachel Becker - A suggested cause of the fire-induced collapse of the World Trade Towers - Fire Safety Journal (Vol. 37, No. 7)
2003/07 - Tomasz Wierzbicki, Xiaoqing Teng - How the airplane wing cut through the exterior columns of the World Trade Center - International Journal of Impact Engineering (Vol. 28, No. 6)
2003/10 - Asif S. Usmani, Yun Chi Chung, Jose L. Torero - How did the WTC towers collapse? A new theory - Fire Safety Journal (Vol. 38, No. 6) - full article
2005/01 - Yukihiro Omika, Eiji Fukuzawa, Norihide Koshika, Hiroshi Morikawa, Ryusuke Fukuda - Structural Responses of World Trade Center under Aircraft Attacks - Journal of Structural Engineering (Vol. 131, No. 1)
2005/01 - Howard R. Baum, Ronald G. Rehm - A simple model of the World Trade Center fireball dynamics - Proceedings of the Combustion Institute (Vol. 30, No. 2) - full article
2005/06 - Asif S. Usmani - Stability of the World Trade Center Twin Towers Structural Frame in Multiple Floor Fires- Journal of Engineering Mechanics (Vol. 131, No. 6)
2005/07 - Jeremy Chang, Andrew H. Buchanan, Peter J. Moss - Effect of insulation on the fire behaviour of steel floor trusses - Fire and Materials (Vol. 29, No. 4)
2005/10 - Mohammed R. Karim, Michelle S. Hoo Fatt - Impact of the Boeing 767 Aircraft into the World Trade Center - Journal of Engineering Mechanics (Vol. 131, No. 10)
2006/09 - Genady P. Cherepanov - Mechanics of the WTC collapse - International Journal of Fracture (Vol. 141, No. 1-2)
2007/03 - Zdenek P. Bazant, Mathieu Verdure - Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions - Journal of Engineering Mechanics (Vol. 133, No. 3) - full article
2007/11 - Ming Wang, Peter Chang, James Quintiere, Andre Marshall - Scale Modeling of the 96th Floor of World Trade Center Tower 1 - Journal of Performance of Constructed Facilities (Vol. 21, No. 6)
2008/01 - Ayhan Irfanoglu, Christoph M. Hoffmann - An Engineering Perspective of the Collapse of WTC-1 - Journal of Performance of Constructed Facilities (Vol. 22, No. 1) - full article
2008/03 - Keith A. Seffen - Progressive Collapse of the World Trade Centre: a Simple Analysis - Journal of Engineering Mechanics (Vol. 134, No. 2) - full article
2008/07 - Genady P. Cherepanov - Collapse of towers as applied to September 11 events - Fizyko-Khimichna Mekhanika Materialiv (Materials Science) (Vol. 44, No. 4)
2005/03 - Genady P. Cherepanov - September 11 And Fracture Mechanics - A Retrospective - International Journal of Fracture (Vol. 132, No. 2)
2007/01 - Genady P. Cherepanov, Ivan E. Esparragoza - Progressive Collapse of Towers: The Resistance Effect - International Journal of Fracture (Vol. 143, No. 2)
2002/11 - Lu Xinzheng, Jiang Jianjing - Simulation for the Collapse of WTC after Aeroplane Impact - Proceedings of the International Conference on Protection of Structures Against Hazard, 14 − 15 November 2002, Singapore - full paper
2003/05 - Venkatash K. R. Kodur - Role of fire resistance issues in the collapse of the Twin Towers - Proceedings of the CIB-CTBUH International Conference on Tall Buildings, 8 - 10 May 2003, Kuala Lumpur - full paper
2003/11 - Abolhassan Astaneh-Asl - World Trade Center Collapse, Field Investigation and Analysis - Proceedings of the Ninth Arab Structural Engineering Conference, 29 November – 1 December 2003, Abu Dhabi - full paper
Articles In Science Magazines
2001/10 - Steven Ashley - When the Twin Towers Fell - Scientific American - full article
2001/10 - Zdenek P. Bazant, Yong Zhou - Why Did the World Trade Center Collapse? - Society for Industrial and Applied Mathematics News (Vol. 34, No. 8) - full article
2002/01 - Henry Petroski - The Fall of Skyscrapers - American Scientist (Vol. 90, No. 1) - full article
See also: Fire Safety Engineering & the Performance of
Structural Steel in Fires
WTC Building 7
WTC 7 Engineering Papers, Collapse Hypotheses, Witness Accounts and Photographic Evidence
NIST, FEMA, & ASCE reports & critiques, WTC collapse analyses,
Articles by and about the tower engineers and investigators, progressive collapse info, engineering resources
Main 9/11 Links Page
"I am disgusted, disgusted with the structural engineers who know the truth about this and are keeping their mouth shut. There’s a special place in Hell reserved for them. And they are going to deserve it." -"Scholar for 9/11 Truth" James Fetzer
The ASCE Pentagon Building Performance Report (PDF) (Dead Link)
World Trade Center
NIST Answers to Frequently Asked Questions About the WTC 1&2 Collapses - August, 2006
NIST Answers to Frequently Asked Questions - December, 2007
NIST Final Reports on WTC 1 & 2
NIST NCSTAR 1 (PDF): URL="http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR%201.pdf"]Federal Building and Fire Safety Investigation of the World Trade Center Disaster: Final Report of the National Construction Safety Team on the Collapses of the World Trade Center Towers[/url]
NCSTAR 1-1 Design, Construction, and Maintenance of Structural and Life Safety Systems
NCSTAR 1-2 Baseline Structural Performance and Aircraft Impact Damage Analysis of the WTC Towers
NCSTAR 1-3 Mechanical and Metallurgical Analysis of Structural Steel
NCSTAR 1-4 Active Fire Protection Systems
NCSTAR 1-5 Reconstruction of the Fires in the World Trade Center Towers
NCSTAR 1-6 Structural Fire Response and Probable Collapse Sequence
NCSTAR 1-7 Occupant Behavior, Egress, and Emergency Communication
NCSTAR 1-8 The Emergency Response Operations
Alternate Collapse Hypotheses
Investigations leading to alternate tower collapse hypotheses, and critiques of NIST's WTC investigation by knowledgeable people who are not conspiracy theorists: FEMA/ASCE, Arup Fire, University of Edinburgh, Usmani, Torero, Lane, Cherepanov, Quintiere, Corbett, Mackey, Greening
Journal and Conference Papers
Peer-reviewed papers and conference papers about the WTC impacts, fires, and collapses
WTC collapse papers with Zdenek Bazant as lead author
What Did and Did not Cause Collapse of WTC Twin Towers in New York Authors Bazant, Le, Greening & Benson. Journal of Engineering Mechanics ASCE 134 (2008). Refutation of controlled demolition theory. Discusses matching of video record with progressive collapse equations, "free-fall" claims, concrete crushing (and how much TNT equivalent would be needed to do that crushing), air pressure & ejection of air, spread of dust cloud.
Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions Co-author Verdure. PDF. Journal of Engineering Mechanics ASCE 133 (2007): pp. 308-319
Excerpt (applies to link above and below): The kinetic energy of the top part of the tower impacting the floor below was found to be about 8.4x larger than the plastic energy absorption capability of the underlying story, and considerably higher than that if fracturing were taken into account (Ba=C5=BEant and Zhou 2002a). This fact, along with the fact that during the progressive collapse of underlying stories the loss of gravitational potential per story is much greater than the energy dissipated per story, was sufficient for Ba=C5=BEant and Zhou (2002a) to conclude, purely on energy grounds, that the tower was doomed once the top part of the tower dropped through the height of one story (or even 0.5 m).
Discussion and replies to June 2006 Bazant & Verdure paper: James Gourley, G. Szuladinski. Closing comments from Bazant to Gourley (after detailed rebuttal to his claims):
Although everyone is certainly entitled to express his or her opinion on any issue of concern, interested critics should realize that, to help discern the truth about an engineering problem such as the WTC collapse, it is necessary to become acquainted with the relevant material from an appropriate textbook on structural mechanics. Otherwise critics run the risk of misleading and wrongly influencing the public with incorrect information.
Bazant & Zhou, 2001-2002: Why Did the World Trade Center Collapse? - Simple Analysis J. Engineering Mechanics ASCE, Sept. 28, 2001, addendum March, 2002.
Other explanations of the tower collapses
November, 2007: Structural Engineer Keith Seffen's mathematical model of WTC tower progressive collapse (PDF. Due to appear in the Journal of Engineering Mechanics, Vol. 134, No. 2, February 2008)
BBC News article about Seffen's paper
Dr. Frank Greening's papers on the Collapses, Energy Transfer, "Tipping," Concrete Pulverization (PDFs)
Physicist Manuel Garcia's Counterpunch articles on the physics of the WTC collapses Pt.1- Pt.2- Pt.3
Why didn't the towers, or the upper portions of them, topple over?
Why didn't the upper part pivot about it's base? See Bazant & Zhou (2001) Appendix II
Eduardo Kausel (MIT): Why the Towers didn't fall like trees
Frank Greening: An analysis of the tipping of the upper section of WTC 2 (PDF)
A simple graphic explanation of why the top of the south tower didn't fall to the side.
Physicist Dave Rogers on tipping of tower tops.
Structural engineer "Newton's Bit" on "tipping"
Explanations of NIST's Investigation Methods
See also: Investigations leading to alternate collapse hypotheses.
NIST's Investigation of the Sept. 11 World Trade Center Disaster: FAQ (2002: Goals & Methods)
Ryan Mackey on how the NIST investigation works, and on "Scholars" critics
Ryan Mackey on NIST's degree of certainty, bounding cases, comparisons to other studies
Ryan Mackey on NIST altering model inputs
Ryan Mackey on NIST recovered steel and fire models
JREF Ktesibios on NIST workstation actual tests
JREF RWGuinn on testing models to failure
Ryan Mackey on NIST fuel load estimates
Physicist Dave Rogers on scaling issues with physical models of large structures
NIST's Recommendations, and the Architectural and Engineering Community's Response
NIST summary of WTC 1 & 2 investigation results & recommendations (PDF)
The AIA's Response to NIST's Draft Report and Recommendations (PDF)
The World Trade Center Collapse and its Implications for International Standards - W. Gene Corley ISO Focus, January 2004 (PDF)
"Reexamining Premises for High-Rise Design" Security Management magazine (PDF)
In this article from Security Management magazine, Dr. Gene Corley discusses lessons from the World Trade Center investigation and how they might affect future building design.
NIBS Building Code Experts: Translating WTC Recommendations into Model Building Codes
First Comprehensive Set of Model Code Changes Adopted Based on Recommendations from Commerce’s NIST World Trade Center Investigation (June, 2007)
Twin Towers' Structural Engineers on the Record
Excellent New Yorker Profile of WTC chief engineer Leslie Robertson, early speculation about collapses, many quotes from engineers, info about skyscraper design
Leslie Robertson on WTC steel core
No Tower Can Withstand Attack As Jets Get Bigger, Expert Says (Les Robertson $ NYT March 14, 2002)
"Reflections on the World Trade Center" (Robertson. PDF)
Jon Magnusson of Skilling Ward, helped design towers: "Engineers couldn't have known"
Gene Corley on FEMA/ASCE investigation lessons
"What We Learned: Building Performance Study of the WTC Collapse" (PDF) Outlines preliminary lessons learned in the FEMA/ASCE investigation of the NY World Trade Center collapse.
"Corley, ASCE Take Part in House Hearing" (PDF) On March 6, CTLGroup senior vice president Dr. Gene Corley testified before the Committee on Science of the U.S. House of Representatives. Dr. Corley was one of several members of the ASCE structural investigation team who were asked to discuss the performance of the World Trade Center in the September 11th attacks, and its implications for future building design. An article on the hearing from ASCE News.
"Looking Back on 9/11" (PDF) In this interview, Dr. Gene Corley discusses engineers' roles in the World Trade Center Building Performance Study
Abolhassan Astaneh-Asl's WTC collapse investigations
Tower Wreckage Reveals Clues - Astaneh - Jersey City Scrap Yards (later, some of these conclusions proved wrong)
Abolhassan Astaneh-Asl WTC Collapse, Field Investigations, and Analysis (Dec. 2003)
Now, as the five-year anniversary of the World Trade Center attack draws near, Astaneh-Asl finally expects to have the results of his analysis published in an academic journal. The project, requiring thousands of hours to complete, was self-funded and conducted by Astaneh-Asl, his students, and analysts from the MSC.Software Corporation, which donated the structural analysis software (MD Nastran and Dytran). Did the Building Do it? (Astaneh Study)
Testimony of Abolhassan Astaneh-Asl Before the House Committee on Science, March, 2002
Investigations involving extensive computer modeling of the towers
April, 2007: Purdue University analysis of WTC 1 collapse using LS-Dyna**More on the Purdue WTC study
"Did the Building Do It?" (Article about Abolhassan Astaneh-Asl/Cal FEA study, Sept, 2006)
Now, as the five-year anniversary of the World Trade Center attack draws near, Astaneh-Asl finally expects to have the results of his analysis published in an academic journal. The project, requiring thousands of hours to complete, was self-funded and conducted by Astaneh-Asl, his students, and analysts from the MSC.Software Corporation, which donated the structural analysis software (MD Nastran and Dytran).
NIST's SAP reference models of WTC 1&2, obtained through FOIA request
LU Xinzheng & JIANG Jianjing Simulation for the Collapse of WTC after Aeroplane Impact. Proceedings of the International Conference on the Protection of Structures Against Hazards, Nov. 2002. 57~60
Weidlinger Report Ties WTC Collapses to Column Failures (Matthys Levy). 10/25/02
The engineering team is comprised of: Weidlinger Associates Inc., led by Matthys Levy and Najib Abboud; LZA Technology/Thornton-Tomasetti Group, led by Daniel Cuoco and Gary Panariello; ARUPFire, led by Richard Custer; Hughes Associates Inc., led by Craig Beyler; SafirRosetti, led by Howard Safir; Hillman Environmental Group, led by Christopher Hillmann and John B. Glass Jr.; RWDI, led by Peter Irwin; Dr. W. Gene Corley, who led the ASCE-FEMA study; Professor Sean Ahearn; and Z-Axis Corp., led by Gary Freed and Alan Treibitz.
Weidlinger Study - Column failures
Weidlinger study refutes FEMA. Collapse inevitable due to structural damage and fires, not to WTC design defects. (NYT Oct 22, 2002)
First Tower to Fall Was hit at Higher Speed, Study Finds (NYT February 23, 2002)
Silverstein Sending Tower Data to U.S. Agency (NIST/Weidlinger/Insurance Agencies NYT Oct 1, 2002)
Even though the exterior columns all looked identical, both the grade and thickness of their steel varied from place to place, said Dr. Fahim Sadek, a researcher at the institute's building and fire research lab, who is producing a detailed structural model of the towers on a computer using the original blueprints. So there were actually more than 130 different column types, he said, each having to be accounted for in his model. From there, it gets only more intricate. One of Dr. Sadek's detailed models for a single floor -- the 96th floor of the north tower, considered typical -- contains 40,000 separate elements. A coarser representation of the entire tower contains 90,000 elements.
Swiss Re/Exponent Failure Analysis Associates WTC engineering study, Oct. 2002 (Complete copies of the FaAA study are available at Swiss Re by calling 212-317-5663.)
Ming Wang, Peter Chang, James Quintiere, and Andre Marshall "Scale Modeling of the 96th Floor of World Trade Center Tower 1" Journal of Performance of Constructed Facilities Volume 21, Issue 6, pp. 414-421 http://www.internationalskeptics.com...60#post3161860
Applied Reseach Associates NIST World Trade Center Investigations
Aircraft Impact Analysis of the World Trade Center Towers (Univ. of Tsukuba)
Jay Windley's (Jay Utah of BAUT forum) excellent explanation of Finite Element Analysis
Structure Magazine: Computer Modeling of the Collapse of the World Trade Center Towers (March, 2007)
CAD Digest article with CAD graphics (September, 2001) G. Charles Clifton
NIST's SAP reference models of WTC 1&2, obtained through FOIA request
More on WTC engineering, articles by and about engineers who worked on the buildings and on the investigations
STRUCTURAL ENGINEERS AT GROUND ZERO - NCSEA (August Domel, Nov. 2001)
The Days After, the Days Ahead: Civil engineers respond to 9/11 Attacks (Civil Engineering, Nov. 2001)
Structural engineers first in the aftermath
Civil Engineering Magazine: Dissecting the Collapses
Articles in the National Academy of Engineering's "The Bridge" Spring, 2002 (PDF):
Editorial: Engineering and Homeland Defense by George Bugliarello
World Trade Center „Bathtub": From Genesis to Armageddon by George J. Tamaro The engineer who oversaw the construction of the World Trade Center „bathtub" describes the recovery efforts.
A 911 Call to the Engineering Profession by Robert Prieto The events of September 11 challenged the future of our heavily engineered environment and the future of the engineering profession.
Early Structural Investigation Teams (through 5/02)
ASCE WTC Disaster Response Team
Engineer Tim Schenck on early GZ work
Multidisciplinary Center for Earthquake Engineering Research (MCEER) The World Trade Center Terrorist Attack: Damage to Critical Facilities and Crisis Response
Georgia Tech Engineering Team Will Conduct Post-Disaster Assessment at World Trade Center Attack Site
Architecture Week: Engineers Explain Collapses (5/2002)
Towers Lost and Beyond: 8 Articles by MIT researchers 2001-2002.
Civil Engineer: WTC & Pentagon Links Portal
Blog: Civil & structural engineers on WTC collapse
Forum on Technical Implications of WTC Collapses (Columbia U., November, 2001)
MIT Masters Thesis: WTC Disaster Analysis & Recommendations (June, 2005)
Designing tall buildings to Resist Earthquakes ($ NYT 2002)
Institute of Structural Engineers: Safety in tall buildings and other buildings of large occupancy ($ 2002)
9/17/01 Inferno Heat, Not Impact, Brought Down Towers, Experts Say
9/19/01: Space.com "Gravity Helped Destroy Twin Towers" concrete too heavy for core construction, walls seen buckling, seismic data
|December, 2007: JOM: The Role of Metallurgy in the NIST Investigation of the
Twin Tower Collapses
|Neither high-rate tests nor recovered components gave any evidence of brittle failure. The high-temperature mechanical properties, necessary for modeling the response to the fires, were consistent with other construction steels.|
Others write about sensibly about the collapses
JREF Nobby Nobbs: Some basics on the physics of the collapses
Bautforum: Jay Utah's excellent explanation of Finite Element Analysis
JREF R. Mackey on Gordon Ross / Frank Greening debate
JREF R.Mackey on freefall and energy available for deformation
JREF R. Mackey on Judy Wood's "Math"
JREF Arkan on tower collapse times
JREF Myriad on kinetic energy of initial collapses
JREF rwguinn on structural steel deformation
JREF Dr. Adequate on Steven Jones' "handwaving" argument.
Physics kinetic energy Moscatelli The destructive forces unleashed
Steven Jones to Jim Fetzer: grand piano speed, damage to bathtub Judy Wood
JREF Kookbreaker on pancake collapse history
Ryan Mackey on independent validations of the NIST report.
Roberts: Were the towers as strong as they were designed to be?
JREF rwguinn: The engineers in my office thought the towers would collapse
More about the NIST & FEMA investigations
In Collapsing Towers, a Cascade of Failures ($ NYT Nov. 11, 2001)
Experts Urging Broader Inquiry In Towers' Fall (NYT Glanz, steel removal, Dec 25, 2001)
NIST to take over collapse investigation ($ NYT January 17, 2002)
Critique of FEMA WTC report by Ed Schulte in Plumbing Engineer, July, 2005 (PDF)
Learning from 9/11 (March, 2002) Hearing before the House Committee on Science: ASCE/FEMA BPAT study
Mismanagement Muddled Collapse Inquiry, House Panel Says (FEMA/NYC gov't/Fed gov't. $ NYT March 7, 2002)
At one point, Representative Anthony D. Weiner, a Democrat from New York City, asked for the official in charge to raise his hand, and two men, and then three appeared to do so. ''We have very serious problems here,'' added Representative John B. Larson, a Connecticut Democrat.
The lack of clear authority has had unfortunate consequences, the House members said. The Giuliani administration started to send World Trade Center steel off to recycling yards before investigators could examine it to determine whether it might hold crucial clues as to why the buildings fell.
The full investigative team set up by FEMA was not allowed to enter ground zero to collect other potentially critical evidence in the weeks after the attack, and it did not get a copy of the World Trade Center blueprints until early January, a delay House members found infuriating.
'The delay in the receipt of the plans did somewhat hinder the team's ability to confirm their understanding of the buildings,'' said Dr. W. Gene Corley, a structural engineer leading the investigative committee organized by FEMA.
A Port Authority spokesman defended the agency, saying that building plans had been given to federal officials within a week of the attack and that the agency was cooperating fully with the inquiry.
The federal officials who testified yesterday -- Dr. Arden L. Bement Jr., the director of the National Institute of Standards and Technology, and Robert F. Shea, the acting administrator of the Federal Emergency Management Agency's Insurance and Mitigation Administration -- repeatedly nodded their agreement.
In response to criticism from one committee member, Mr. Shea said, ''Frankly, I agree with you. There are many things in hindsight we would have done differently.''
The problem, they said, was the lack of clear authority in federal law and financing. None of the investigators, for example, had subpoena power, meaning that they could not order the city to stop sending the steel off for recycling or demand a copy of the building blueprints.
Government Orders Inquiry Into Trade Center Collapse ($ NYT March 23, 2002)
The Trade Center; Towers Fell as Intense Fire Beat Defenses, Report Says (FEMA. $ NYT March 29, 2002)
Interviews will examine why trade center collapsed -100,000 workers issued security passes
Wider Inquiry Into Towers Is Proposed ($ NYT May 2, 2002)
"In Data Trove, a Graphic Look at Towers' Fall, ($ NYT October 29, 2002)
Twin Tower Collapse Theory Challenged (Feb. 2003)
NIST Minutes of December 2-3, 2003, Meeting
New Evidence Is Reported That Floors Failed on 9/11 ($ NYT Dec. 3, 2003)
S. Shyam Sunder, who is leading the investigation for the National Institute of Standards and Technology in the Commerce Department, said, ''We are seeing evidence of floors appearing to be sagging -- or that had been damaged -- prior to collapse.'' Still, Dr. Sunder said, ''The relative role of the floors and the columns still remain to be determined in the collapse.''
NIST Not Ruling Anything Out on WTC Probe
Reliving 9/11, With Fire as Teacher (Modeling. $ NYT, Jan. 6, 2004)link
NIST Public Briefing 05/05/04
Fire Testing Is Questioned In Findings On Towers (Current testing standards for new buildings inadequate. $ NYT August 26, 2004)
WTC Twin Tower Construction Details Pertinent to Engineering Investigations
See also WTC Construction, Systems, Power and WTC Core Construction
Gregory Urich: Detailed Estimate of Mass and Potential Energy of World Trade Center Tower (pdf)
WTC 1 & 2 core column data
Report of WTC fire code compliance--1993 (pdf)
Truther Claim: the term "Progressive Collapse" is a new one and describes a phenomenon rarely or never seen before 9/11.
Jim Hoffman, whom many truthers describe as one of their best researchers:
You've heard that the Twin Towers pancaked, crushing themselves completely. The experts gave us a fancy-sounding term for this: progressive collapse. If you search with the phrase "progressive collapse" you will find numerous articles, most of them written since 9/11/01 about things like assessing and retrofitting existing structures against progressive collapse. It seems that the only examples of progressive collapse of buildings cited are the Twin Towers, Building 7, and the Murrah Federal Building in Oklahoma City.
A few examples of reality:
"As the hon. Gentleman will know, I accepted the tribunal's recommendations in respect of gas which show that once buildings are strengthened against the possibility of progressive collapse there is no reason why gas should not be used..." -Ronan Point Flats (Report), November, 1968
"New safeguards against the progressive collapse of tall buildings..." -"New Safety Law for Buildings," The Times (London), February 6, 1970
"The engineering term 'progressive collapse' - a potential calamity in high-rise structures - carries a sad double meaning throughout the evening." -'Benefactors' by Frayn, The New York Times, December 23, 1985
'It was a progressive collapse,'' Mr. Cohen said. ''What touched it off, we don't know.'' -"Collapse Inquiry Studies Bracing for New Column," The New York Times, May 1, 1987.
Some Progressive Collapse Studies & Recommendations
Thanks to JREF forum member cmcaulif for his contributions
Progressive Collapse Basics (R. Shankar Nair. 2004 North American Steel Construction Conference. PDF)
Fire Induced Progressive Collapse. (Arup. PDF) "This paper considers issues related to fire induced progressive collapse of tall buildings in extreme events."
Fire induced progressive collapse analysis of high rise buildings
NISTIR 7396 "Best Practices for Reducing the Potential for Progressive Collapse in Buildings," February 2007
Above report based on NIST/SEI workshops. Workshop presentation materials are here
Abolhassan Astaneh-Asl: Progressive collapse prevention in new and existing buildings (Includes use of catenary action of cables to resist collapse. 2003. pdf).
Practical Means for Energy-Based Analyses of Disproportionate Collapse Potential
Journal of Performance of Constructed Facilities, Volume 20, Issue 4, pp. 336-348 (November 2006)
Progressive Analysis Procedure for Progressive Collapse
Journal of Performance of Constructed Facilities, Volume 18, Issue 2, pp. 79-85 (May 2004)
Progressive Collapse of Structures: Annotated Bibliography and Comparison of Codes and Standards
Journal of Performance of Constructed Facilities, Volume 20, Issue 4, pp. 418-425 (November 2006)
Cheol-Ho Lee, Seonwoong Kim, Kyu-Hong Han, Kyungkoo Lee 2009. "Simplified nonlinear progressive collapse analysis of welded steel moment frames"
Journal of Constructional Steel Research, Volume 65, Issue 5, 1130-1137
Feng Fu, "Progressive collapse analysis of high-rise building with 3-D finite element modeling method" Journal of Constructional Steel Research, In Press, Corrected Proof, Available online 13 March 2009
A.G. Vlassis, B.A. Izzuddin, A.Y. Elghazouli, D.A. Nethercot, "Progressive collapse of multi-storey buildings due to failed floor impact" Engineering Structures, In Press, Corrected Proof, Available online 12 March 2009
Abstract excerpt: "The application of the proposed methodology is demonstrated by means of a case study, which considers the impact response of a floor plate within a typical multi-storey steel-framed composite building. ...The application study illustrates the extremely onerous conditions imposed on the impacted floor resulting in an increased vulnerability to progressive collapse for structures of this type."
B.A. Izzuddin, A.G. Vlassis, A.Y. Elghazouli, D.A. Nethercot, "Progressive collapse of multi-storey buildings due to sudden column loss - Part I: Simplified assessment framework" Engineering Structures, Volume 30, Issue 5, May 2008, Pages 1308-1318
A.G. Vlassis, B.A. Izzuddin, A.Y. Elghazouli, D.A. Nethercot, "Progressive collapse of multi-storey buildings due to sudden column loss - Part II: Application" Engineering Structures, Volume 30, Issue 5, May 2008, Pages 1424-1438
Santiago Pujol, J. Paul Smith-Pardo 2009. "A new perspective on the effects of abrupt column removal" Engineering Structures, Volume 31, Issue 4, 869-874
Hyun-Su Kim, Jinkoo Kim, Da-Woon An, "Development of integrated system for progressive collapse analysis of building structures considering dynamic effects" Advances in Engineering Software, Volume 40, Issue 1, January 2009, Pages 1-8
Jinkoo Kim, Taewan Kim, "Assessment of progressive collapse-resisting capacity of steel moment frames" Journal of Constructional Steel Research, Volume 65, Issue 1, January 2009, Pages 169-179
Jeom Kee Paik, Bong Ju Kim, "Progressive collapse analysis of thin-walled box columns" Thin-Walled Structures, Volume 46, Issue 5, May 2008, Pages 541-550
The following individuals and groups participated in the 911 investigations, cleanup and research. Not one has come forward to support the Truther version of events.
7,000+ FBI Agents who conducted a three-year 911 investigation
1,500 people who worked the flight 93 crash scene
40,000 people who worked the piles at Ground Zero
55 FBI Evidence Response Teams at Fresh Kills in New York
8,000+ people who worked the scene at the Pentagon
Notice the number of civil and structural engineers in this list
Abolhassan Astaneh-Asl, Ph.D., P.E. / Aine M. Brazil, P.E., S.E. / Alan Rosa, P.E., S.E. / Alfred D. Barcenilla, Sr., P.E. / Allan Jowsey, Ph.D. / Allyn Kilsheimer, P.E., S.E. / Amit Bandyopadhyay, S.E. / Amy Zelson Mundorff / Anamaria Bonilla, S.E. / Andre Sidler, P.E., S.E. / Andrei Reinhorn, Ph.D., P.E., S.E. / Andrew Coats, P.E., S.E. / Andrew McConnell, S.E. / Andrew Mueller-Lust, S.E. / Andrew Pontecorvo, P.E. / Andrew Whittaker, Ph.D., P.E., S.E. / Anthony Kirk US&R Structural Specialist / Anthony W. Chuliver, S.E. / Antoine E. Naaman, Ph.D. / Antranig M. Ouzoonian, P.E. / Arlan Dobson, FEMA Region 2 DAS / Arthur Schuerman, FDNY (ret.) / Asif Usmani, Ph.D., B.E. / August Domel, Ph.D., S.E., P.E. / Ayhan Irfanoglu, P.E., S.E. / Barbara Lane, Ph.D. / Bernie Denke, P.E. US&R Structural Specialist / Bill Cote / Bill Coulbourne, P.E., S.E. / Bill Crowley, special agent, FBI / Bill Daly, senior vice president, Control Risks Group / Bill Scott (Capt. USAF, Ret.), / Bill Uher, NASA Langley Research Center / Bob Gray (I.U.O.E.) / Bonnie Manley, P.E., S.E. / Boris Hayda, P.E., S.E. / Brian Lyons, Tully / Brian McElhatten, S.E. / Brian Smith (Col.), Chief Deputy Medical Examiner, Dover AFB / Brian Tokarczik, P.E., S.E. / Charles Hirsch, M.D. / Charles J. Carter, P.E., S.E. / Charles Thornton, P.E. / Charlie Vitchers / Christoph Hoffmann, Ph.D., Purdue University / Christopher E. Marrion, P.E. / Christopher M. Hewitt, AISC / Christopher N. McCowan / Chuck Guardia, S.E. / Conrad Paulson, P.E., S.E. / Curtis S.D. Massey / D. Stanton Korista, P.E., S.E. / Dan Doyle (IW 40) / Dan Eschenasy, P.E., S.E. / Dan Koch Jr. / Daniel A. Cuoco, P.E / Daniele Veneziano, P.E. / David Biggs, P.E., S.E. / David Cooper, P.E. / David Davidowitz, ConEd / David Hoy, S.E. / David J. Hammond, P.E., S.E. / David Leach, P.E. / David M. Parks, ME / David Newland Sc.D., FREng. / David Peraza, P.E., S.E. / David Ranlet / David Schomburg / David Sharp, S.E. / David T. Biggs, P.E. / Dean Koutsoubis, S.E. / Dean Tills, P.E. / Delbert Boring, P.E. / Dennis Clark (IST) / Dennis Dirkmaat, Ph.D. / Dennis Mileti, Ph.D. / Dennis Smith / Dharam Pal, M.E. / Dick Posthauer, S.E. / Donald Friedman, P.E. / Donald O. Dusenberry, P.E. / Ed Jacoby Jr., NYSEMO / Ed McGinley, P.E. / Ed Plaugher, Chief, Arlington FD / Edward A. Flynn, Arlington Police Chief / Edward M. DePaola, P.E., S.E. / Edward Stinnette, Chief, FCFD / Eiji Fukuzawa / Fahim Sadek, P.E., S.E. / Farid Alfawakhiri, Ph.D., P.E., S.E. / Frank Vallebuono, FDNY Battalion Chief / Anthony Varriale, FDNY Captain / Frank Cruthers, FDNY Chief / Frank Fellini, FDNY Chief / Joseph Callan, FDNY Chief / Daniel Nigro, FDNY Chief of Operations / Nick Visconti, FDNY Deputy Chief / Peter Hayden, FDNY Deputy Chief / Sam Melisi, FDNY Firefighter / Forman Williams, Ph.D., P.E. / Francis J. Lombardi, P.E. / Frank Gayle, Sc.D. / Frank Greening, Ph.D. / Fred E.C. Culick, Ph.D., S.B. / Fred Endrikat, FEMA USAR / Gary Keith, V.P. NFPA / Gary Steficek, S.E. / Gary Tokle, Asst. VP, NFPA / George Tamaro, P.E., S.E. / Gerald Haynes, P.E. / Gerald Wellman US&R Structural Specialist / Glenn Corbett / Graeme Flint / Guy Colonna, P.E., NFPA / Guylene Proulx, Ph.D. / H.S. Lew, P.E., S.E. / Hal Bidlack, Lt. Col. USAF (ret.), Ph.D. / Harold E. Nelson, P.E., FSFP.E. / Harry Martin, AISC / Howard R. Baum, Ph.D., M.E. / J. David Frost, Ph.D., P.E. / J. David McColskey / Jack Brown Deputy Chief Loudoun County (Va.) Fire Rescue Department / Jack Messagno, WTC project Manager (Tully) / Jack Spencer, P.E. / Jacques Grandino, P.E., S.E. / James A. Rossberg, P.E. / James Chastain US&R Structural Specialist / James H. Fahey, S.E. / James J. Cohen, P.E., S.E. / James J. Hauck, P.E., S.E. / James Lord, FSFP.E. / James Milke, Ph.D., P.E. / James Quintiere, Ph.D., P.E. / Jan Szumanski, IUOE / Jason Averill, FSFP.E. / Jeff Rienbold, NPS / Jeffrey Hartman, S.E. / Jim Abadie, Bovis / Joel Meyerowitz / John Fisher, Ph.D., P.E., / John Flynn, P.E. / John Gross, Ph.D., P.E. / John Hodgens, FDNY (ret.) / John J. Healey, Ph.D., P.E. / John J. Zils, P.E., S.E. / John L. Gross, Ph.D., P.E. / John Lekstutis, P.E. / John M. Hanson, Ph.D, P.E. / John McArdle NYPD/ESU (DTC) / John Moran, NYPD/ESU (NTC) / John O'Connell, Chief FDNY / John Odermatt (NYC OEM) / John Ruddy, P.E., S.E. / John Ryan, PAPD / John W. Fisher, P.E. / Jon Magnusson, P.E., S.E. / Jonathan Barnett, Ph.D / Joo-Eun Lee P.E., S.E. / Jos=C3=A9 Torero, Ph.D. / Joseph C. Gehlen, P.E., S.E. / Joseph Englot, P.E., S.E. / Jozef Van Dyck, P.E. / Juan Paulo Morla, S.E. / Karen Damianick, P.E. / Karl Koch III / Karl Koch IV / Kaspar Willam, P.E., S.E. / Keith A. Seffen, MA, Ph.D. / Ken Hays / Kenneth Holden / Kent Watts / Kevin Brennan, OSHA / Kevin Malley, FDNY (ret.) / Kevin Terry, S.E. / Kurt Gustafson, P.E., S.E. / Larry Keating (IW 40) / Lawrence C. Bank, Ph.D., P.E. / Lawrence Griffis, P.E. / Lawrence Novak, P.E., S.E. / Leo J. Titus, P.E. / Leonard M. Joseph, P.E. / Leslie E. Robertson, P.E., S.E. / Long T. Phan, Ph.D., P.E. / Lou Mendes, P.E., S.E. / Louis Errichiello, S.E. / Manny Velivasakis, P.E. / Mark Blair / Mark Kucera, USACE / Mark Pierepiekarz, P.E., S.E. / Mark Stahl / Mark Tamaro, P.E / Mark Volpe, IW 40 / Marty Corcoran / Matthew G. Yerkey, P.E., S.E. / Matthew McCormick, NTSB / Melbourne Garber, P.E., S.E. / Merle E. Brander, P.E. / Mete A. Sozen, Ph.D., S.E. / Michael Burton, P.E. / Michael Dallal / Michael Fagel, Ph.D., CEM / Michael Hessheimer, S.E. / Michael K. Hynes, Ed.D., ATP, CFI / Michael Tylk, P.E., S.E. / Michel Bruneau, Ph.D., P.E., S.E. / Mike Banker, FDNY Capt. (SOC) / Mike Marscio, P.E. / Miroslav Sulc,, P.E., S.E. / Mohammed Ettouney / Mohammed R. Karim, Ph.D. / Morgan Hurley, FSFP.E. / Nestor Iwankiw, Ph.D., P.E. / Nick Carcich / Norman Groner, Ph.D. / Pablo Lopez, P.E., S.E. / Patrick McNierney, P.E., S.E. / Paul A. Bosela, Ph.D., P.E. / Paul F. Mlakar, Ph.D., P.E. / Paul Sledzik / Paul Tertell, P.E. / Pete Bakersky / Peter Chipchase, S.E. / Peter Rinaldi, P.E. / Phillip Murray, P.E. / Pia Hoffman / Rajani Nair, S.E. / Ralph Castillo, P.E., F.P.E. / Ralph D'Apuzo, P.E. / Ramon Gilsanz, P.E., S.E / Randy Lawson / Raul Maestre, P.E., S.E. / Raymond F. Messer, P.E. / Raymond H.R. Tide, P.E., S.E. / Reidar Bjorhovde, Ph.D., P.E / Richard Bukowski P.E., FSFP.E. / Richard G. Gewain, P.E., S.E. / Richard Gann, Ph.D. / Richard Garlock, P.E., S.E. / Richard J. Fields, Ph.D. / Richard Kahler US&R Structural Specialist / Robert Athanas (thermal imaging specialist, FDNY) / Robert C. Sinn, P.E., S.E. / Robert Clarke, S.E. / Robert F. Duval (NFPA) / Robert Frances US&R Structural Specialist / Robert J. McNamara, P.E., S.E. / Robert L. Parker, Ph.D. / Robert Ratay, Ph.D., P.E., S.E. / Robert Shaler, M.D. / Robert Smilowitz, Ph.D., P.E / Robert Solomon, P.E. / Robert Wills, AISC / Ron Dokell, president, Demolition Consultants / Ronald Greeley, Ph.D. / Ronald Hamburger, P.E., S.E. / Ronald J. LaMere, P.E. / Ronald Rehm, Ph.D. / Ronald Spadafora, FDNY D.A.C / Ruben M. Zallen, P.E. / Russell "Rusty" Dodge Jr, Asst. Chief, Fort Belvoir FD / Ryan Mackey / S. Shyam Sunder, P.E., S.E. / Saroj Bhol, P.E. / Saw-Teen See, P.E. / Shankar Nair. P.E., S.E. / Shawn Kelly, Arlington County Fire Marshal / Skip Aldous, Lt. Col., U.S. Air Force (Ret.) / Socrates Ioannides, P.E., S.E. / Sonny Scarff / Stan Murphy, P.E. / Stephen Cauffman / Stephen W. Banovic, Ph.D. / Steve Douglass, image analysis consultant / Steve Rasweiler, FDNY B.C. (SOC) / Steve Spall, P.E., S.E. / Stuart Foltz, P.E. / Terry Sullivan, Bovis / Theodore Galambos, P.E. / Theodore Krauthammer, Ph.D., P.E. / Therese P. McAllister, Ph.D., P.E. / Thomas A. Siewert / Thomas Eagar, Sc.D., P.E. / Thomas Hawkins Jr, Chief, AFD / Thomas R. Edwards, Ph.D / Thomas Schlafly, AISC / Timothy Foecke, Ph.D. / Todd Curtis, Ph.D / Todd Ude, P.E., S.E. / Tom Scarangello, P.E. / Tom Stanton (IST) / Tomasz Wierzbicki / Tony Beale, P.E. / Valentine Junker / Van Romero, Ph.D. / Venkatesh Kodur, Ph.D., P.E. / Victor Hare, P.E. / Victoria Arbitrio, P.E. / Vincent Dunn, FDNY (ret.) / W. Gene Corley, Ph.D., P.E., S.E. / W. Lee Evey / Wallace Miller / William Baker, P.E., S.E / William E. Luecke, Ph.D. / William Grosshandler, Ph.D., ME / William Howell, P.E., S.E. / William Koplitz photo desk manager, FEMA / William McGuire, P.E. / Willie Quinlan, IW / Won-Young Kim, Ph.D / Yates Gladwell pilot, VF Corp. / Yukihiro Omika / Zdenek Bazant, Ph.D., S.E. /</div>ACE Bermuda Insurance / AEMC Construction / AIG Insurance / Air Traffic Control System Command Center in Washington / Alexandria VA Fire & Rescue / Allianz Global Risks / American Airlines / American Concrete Institute / American Institute of Steel Construction / American Red Cross / Applied Biosystems Inc. / Applied Research Associates / Arlington County Emergency Medical Services / Arlington County Fire Department / Arlington County Sheriff's Department / Arlington VA Police Department / Armed Forces Institute of Pathology / Armed Forces Institute of Technology Federal Advisory Committee / ARUP USA / Atlantic Heydt Inc. / Bechtel / Berlin Fire Department / Big Apple Wrecking / Blanford & Co. / Bode Technology Group / Bovis Inc. / Building and Construction Trades Council / Bureau of Alcohol Tobacco and Firearms / C-130H crew in D.C. & Shanksville / Cal Berkeley Engineering Dept. / California Incident Management Team / Carter Burgess Engineering / Celera Genomics / Centers for Disease Control / Central City Fire Department / Central Intelligence Agency / Cleveland Airport control tower / Columbia University Department of Civil Engineering and Engineering Mechanics / Congressional Joint Intelligence Committee / Consolidated Edison Company / Construction Technologies Laboratory / Controlled Demolitions Inc. / Council on Tall Buildings and Urban Habitat / Counterterrorism and Security Group / CTL Engineering / D.H. Griffin Wrecking Co. Inc. / DeSimone Consulting Engineers / Dewhurst MacFarlane &Partners / DiSalvo Ericson Engineering / District of Columbia Fire & Rescue / DOD Honor Guard, Pentagon / D'Onofrio Construction / E-4B National Airborne Operations Center crews / Edwards and Kelcey Engineering / Engineering Systems, Inc. / Environmental protection Agency / Exponent Failure Analysis Associates / EYP Mission CriticalFacilities / Fairfax County Fire & Rescue / Falcon 20 crew in PA / Family members who received calls from victims on the planes / FBI Evidence Recovery Teams / Federal Aviation Administration / Federal Bureau of Investigation / Federal Emergency Management Agency / Federal Insurance Co. / FEMA 68-Person Urban Search and Rescue Teams: Arizona Task Force 1, California Task Force 1, California Task Force 3, California Task Force 7, Colorado Task Force 1, Fairfax Task Force 1, Florida Task Force 1, Florida Task Force 2, Maryland Task Force 1, Massachusetts Task Force 1, Metro Dade/Miami, Nebraska Task Force 1, New Mexico Task Force 1, New York Task Force 1, Pennsylvania Task Force 1, Tennessee Task Force 1, Texas Task Force 1, Utah Task Force 1, Virginia Task Force 1, Virginia Task Force 2, Washington Task Force 1 / FEMA Disaster Field Office / FEMA Emergency Response Team / FEMA Urban Search and Rescue Incident Support Team-Advanced 3 / Fire Department of New York / Fort Myer Fire Department / French Urban Search & Rescue Task Force / Friedens Volunteer Fire Department / Gateway Demolition / Gene Code Forensics / Georgia Tech Engineering Dept. / Gilsanz Murray Steficek LLP / GMAC Financing / Goldstein Associates Consulting Engineers / Guy Nordenson Associates / HAKS Engineers / Hampton-Clarke Inc. / HHS National Medical Response Team / HLW International Engineering / Hooversville Rescue Squad. / Hooversville Volunteer Fire Department / Hoy Structural Services / Hughes Associates, Inc / Hugo Neu Schnitzer East / hundreds of ironworkers, some of whom built the WTC / Hundreds of New York City Police Department Detectives / Industrial Risk Insurers / Institute for Civil Infrastructure Systems / International Association of Fire Chiefs / International Union of Operating Engineers Locals 14 & 15 / J.R. Harris & Company / Johnstown-Cambria County Airport Authority / Karl Koch Steel Consulting Inc. / KCE Structural Engineers / Koch Skanska / Koutsoubis, Alonso Associates / Laboratory Corp. of America / Lamont-Doherty Earth Observatory / Leslie E. Robertson Associates / LIRo Engineering / Listie Volunteer Fire Company / Lockwood Consulting / M.G. McLaren Engineering / Masonry Society / Mazzocchi Wrecking Inc. / Metal Management Northeast / Metropolitan Airport Authority Fire Unit / Miami-Dade Urban Search & Rescue / Military District of Washington Search & Rescue Team / Montgomery County Fire & Rescue / Mueser Rutledge Consulting Engineers / Murray Engineering / Myriad Genetic Laboratories Inc. / National Center for Biotechnology Informatics / National Commission on Terrorist Attacks Upon the United States / National Council of Structural Engineers Associations / National Disaster Medical System / National Emergency Numbering Association / National Fire Protection Association / National Guard in D.C., New York, and Pennsylvania / National Institute of Standards and Technology (NIST) / National Institutes of Health Human Genome Research Institute / National Law Enforcement and Security Institute / National Military Command Center / National Reconnaissance Office / National Response Center / National Science Foundation Division of Civil and Mechanical Systems / National Security Agency / National Transportation Safety Board / National Wrecking / Natural Hazards Research and Applications Information Center / New Jersey State Police / New York City Department of Buildings WTC Task Force / New York City Department of Design and Construction / New York City Department of Environmental Protection / New York City Office of Emergency Management / New York City Office of the Chief Medical Examiner / New York City Police Department Aviation Unit / New York City Police Department Emergency Services Unit / New York Daily News / New York Flight Control Center / New York Newsday / New York Port Authority Construction Board / New York Port Authority Police / New York State Emergency Management Office / New York State Police Forensic Services / New York Times / North American Aerospace Defense Command / Northeast Air Defense Sector Commanders and crew / Numerous bomb-sniffing dogs / Numerous Forensic Anthropologists / Numerous Forensic Dentists / Numerous Forensic Pathologists / Numerous Forensic Radiologists / NuStats / Occupational Safety and Health Administration / Office of Emergency Preparedness / Office of Strategic Services / Orchid Cellmark / Parsons Brinckerhoff Engineering / Pennsylvania Department of Environmental Protection / Pennsylvania Department of Health and Human Services / Pennsylvania Region 13 Metropolitan Medical Response Group / Pennsylvania State Funeral Directors Association / Pennsylvania State Police / Pentagon Defense Protective Service / Pentagon Helicopter Crash Response Team / Pentagon Medical Staff / Pentagon Renovation Team / Phillips & Jordan, Inc. / Port of New York and New Jersey Authority / Pro-Safety Services / Protec / Public Entity Risk Institute / Purdue University Engineering Dept. / Robert Silman Associates Structural Engineers / Rolf Jensen & Associates, Inc / Rosenwasser/Grossman Consulting Engineers / Royal SunAlliance/Royal Indemnity / SACE Prime Power Assessment Teams / SACE Structural Safety Engineers and Debris Planning and Response Teams / Salvation Army Disaster Services / several EPA Hazmat Teams / several FBI Hazmat Teams / several Federal Disaster Medical Assistance Teams / several Federal Disaster Mortuary (DMORT) Teams / Severud Associates Consulting Engineers / Shanksville Volunteer Fire Company / Silverstein Properties / Simpson Gumpertz & Heger Engineers / Skidmore, Owings & Merrill LLP / Skilling Ward Magnusson Barkshire / Society of Fire Protection Engineers / Somerset Ambulance Association / Somerset County Coroner's Office / Somerset County Emergency Management Agency / Somerset Volunteer Fire Department / St. Paul/Travelers Insurance / State of Pennsylvania Emergency Management Agency / Stoystown Volunteer Fire Company / Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE) / Structural Engineers Association of New York / Superstructures Engineering / Swiss Re America Insurance / Telephone operators who took calls from passengers in the hijacked planes / Teng & Associates / Thornton-Tomasetti Group, Inc. / TIG Insurance / Tokio Marine & Fire / Transportation Safety Administration / Tully Construction / Twin City Fire Insurance / Tylk Gustafson Reckers Wilson Andrews Engineering / U.S. Army Corps of Engineers / Underwriters Laboratories / Union Wrecking / United Airlines / United States Air National Guard / United States Fire Administration / United States Secret Service / United Steelworkers of America / University of Sheffield Fire Engineering Research / US Army Reserves of Virginia Beach Fairfax County and Montgomery County / US Army’s Communications-Electronics Command / US Department of Defense / US Department of Justice / US Department of State / Virginia Beach Fire Department / Virginia Department of Emergency Management / Virginia State Police / Vollmer Associates Engineers / Washington Post / Weeks Marine / Weidlinger Associates / Weiskopf & Pickworth Engineering / Westmoreland County Emergency Management Agency / Whitney Contracting / Willis Group Holdings / WJE Structural Engineers / Worcester Polytechnic Institute / World Trade Center security staff / XL Insurance / Yonkers Contracting / York International / Zurich Financial / Zurich Re Risk Engineering
Here are people who worked on 9/11 matters in one way or another. All had specialized training in whatever aspect of the work they did. Not one has come forward to support the 9/11 Truth version of events: 7,000+ FBI Agents who conducted a three-year 911 investigation; 1,500 people who worked the flight 93 crash scene; 40,000 people who worked the piles at Ground Zero; 55 FBI Evidence Response Teams at Fresh Kills in New York; 8,000+ people who worked the scene at the Pentagon. There are at least five peer-reviewed journal articles in ASCE publications that conclude the buildings came down by fire and those Journal articles have been cited in other articles and used to redesign fire codes in tall buildings (meaning that the articles have peer respect). NIST was peer-reviewed by four independent civil engineering firms and concluded fire brought the buildings down. "What Did and Did Not Cause the Collapse of the WTC Towers in NY" is another. That was produced by the Department of Civil Engineering at Northwest University (Structural Engineering Report No 07-05 / C605c).