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Why Fact-check? Why preserve a visual record?

The Website Written as a Book
Introduction
1: Science and Subjective Viewpoints
2: Toward Accurate Collapse Histories
....2.1: Progressive Floor Collapses in the WTC Towers
....2.2: General Global Characteristics of Collapses
....2.3: Mathematical Basis of ROOSD Propagation
....2.4: WTC1 Accurate Collapse History
....2.5: WTC2 Accurate Collapse History
....2.6: WTC7 Accurate Collapse History
3: WTC Collapse Misrepresentations
....3.1: Purpose of the NIST Reports
....3.2: NIST WTC1 Misrepresentations
....3.3: NIST WTC7 Misrepresentations
....3.4: NIST WTC2 Misrepresentations
....3.5: Reviewing the Purpose of NIST and FEMA Reports
....3.6: Bazant Misrepresentation of Collapse Progressions
....3.7: Block Misrepresentations of Collapse Progressions
....3.8: AE911T Misrepresentations of the Collapses
4: Scientific Institutions Can Be Unaware of Contradiction
5: Reassessing the Question of Demolition
....5.1: The Case of WTC1
....5.2: The Case of WTC2
....5.3: The Case of WTC7
6: WTC Collapse Records Studied as Meme Replication
....6.1: Meme Replication in Technical Literature
....6.2: Meme Replication in Mass Media
....6.3: Meme Replication in Popular Culture
....6.4: John Q Public and the WTC Collapse Records
Conclusions

WTC Twin Towers Collapse Dynamics

Official, Legal Attempts to Explain Collapses

Academic Attempts to Explain Collapses Reviewed

On the Limits of Science and Technology

WTC Video Record

WTC Photographic Record
WTC1 Attack to Collapse
WTC2 Attack to Collapse
WTC 7
.
-----PHOTO RECORD OF FIRE PROGRESSION-----
Fire Progression, WTC1 North Face
Fire Progression, WTC1 South Face
Fire Progression, WTC1 East Face
Fire Progression, WTC1 West Face
Fire Progression, WTC2 North Face
Fire Progression, WTC2 South Face
Fire Progression, WTC2 East Face
Fire Progression, WTC2 West Face
.
----DEBRIS LAYOUT AND CONDITION, BY REGION-----
Debris: WTC1 Around Footprint
Debris: WTC2 Around Footprint
Debris: From WTC1 Westward
Debris: From WTC1 Northward
Debris: From WTC2 Eastward
Debris: From WTC2 Southward
Debris: Plaza Area, Northeast Complex
Debris: Hilton Hotel, Southwest Complex
Debris: General, Unidentified Locations
Damage to Surrounding Buildings
Perimeter Column Photo Record
Perimeter Columns: Types of Damage
Core Box Columns: Types of Damage
Complete Photo Archive
Other Major 9-11 Photo Archives
The 911Dataset Project

WTC Structural Information

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Online Misrepresentations of the WTC Collapses

Forum, Blog Representations of the WTC Collapses

The Book Tested Through Experiments

Miscellaneous Notes, Resources
FAQ for Miscellaneous Notes
History Commons 9/11 Timeline
The 911Dataset Project
Skyscraper Safety Campaign
First and Largest 9/11 Conspiracy Theory
Key Words in Book and Website
Trapped Within a Narrowed False Choice
Vulnerability and Requestioning
On Memes and Memetics
Obedience, Conformity and Mental Structure
Denial, Avoidance (Taboo) and Mental Structure
Taboos Against Reviewing the Collapse Events
Extreme Situations and Mental Structure
Suggestibility, Hypnosis and Mental Structure
Awareness and Behavior
Magical, Religious, Scientific Cause-Effect Relations
The Extreme Limits of Mental Dysfunction
Orwell's "Crimestop", "Doublethink", "Blackwhite"
William James, Max Born: Science as Philosophy
Plato on Self Reflection and Mental Structure
Rewriting History, part 1
Rewriting History, part 2
On Smart Idiots

New Ideas in Education

More WTC Academic Papers

More WTC Academic Papers




American Society of Civil Engineering, Journal of Engineering Mechanics

Over decade of proudly misrepresenting the collapse progression modes of the twin towers.


ASCE library linked here

In one of the best examples of the validity of the thesis of my "book", anyone who wishes can go to the library, run a search for "world trade center" and see not a single correct representation of the collapse progression modes of the twin towers. Not a single contributing author to the journals was able to positively identify anything like what we now know as ROOSD in more than a decade of publications.

As late as 2011 the journals published peer reviewed papers by Dr Grabbe and Dr Bazant, Mr Block himself, that misrepresent the collapse progression modes of the twin towers. A.S Usmani is also included in the journals, whose representation of sagging floors was examined by enik.

Dr Bazant leads the way with 4 papers which misrepresent the collapse progression processes literally in terms of "crush down, then crush up" from 2007 to 2011. Dr Seffen is also included in the journals.



Therefore, a special place in part 2 of the book, WTC collapse misrepresentations, will be made for the ASCE and the Journal of Engineering Mechanics to demonstrate how they repeatedly misrepresented the collapse progression modes. Another section will be made for Steven Jones.

In the follow-up experiments I'll contact the editors of the journal to record their explanation for why they allow these cartoon representations to the collapses into their journals. Actually, I'll visit them in person and make a video of their responses as to how they were unable to identify the ROOSD process in even a single paper in over a decade, while publishing the block representations they did.

Nothing can demonstrate the cluelessness and lack of integration between behavior and awareness among the highly educated wrt to the WTC towers better than ASCE and the NIST.

Over a decade of publications within ASCE serve as a confessional of how little they understood the collapse progression processes of the towers and how poorly they served the public interest during that time. In that time not a single author was able to spot the largest chain of cascading floor collapses in engineering history for what it was.


Note that nobody forced them to insert their feet so deeply into their own mouths. They did so willingly and through the peer review process. Nobody tricked the people reviewing these papers or the people publishing these papers to insert their feet into their mouths so deeply. Nobody tricked the authors to write so poorly.

If such extreme gullibility exists at that level of education and on that scale, isn't it prudent that you, too, approach the subjects of collapse and demolition with more caution and awareness in your own observations? With more awareness of your own vulnerability to false technical claims?

If they can be fooled so easily, you can too.



Ayhan Irfanoglu1 and Christoph M. Hoffmann2

1Assistant Professor of Civil Engineering, School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907. E-mail: ayhan@purdue.edu

2Professor of Computer Science and Director of Rosen Center for Advanced Computing, Dept. of Computer Science, Purdue University, West Lafayette, IN 47907. E-mail: cmh@cs.purdue.edu

The writers report on a simulation study of the performance of the North Tower (WTC-I) of the World Trade Center complex during the impact of American Airlines Flight 11 on September 11, 2001. We discuss impact damage that the structural core might have sustained and its possible behavior under structural and thermal loading. Our simulations indicate that the worst damage to the core structure was in stories 95 through 97 of the tower. We estimate that a core collapse mechanism could be initiated if the tower core column temperatures were elevated to about 700°C .


Paper written in 2008. More accurate mappings of early movement do indicate that WTC1 was a core-led failure. No indications of 700C temperatures in the core. These contradictions were most probably overlooked because the NIST misrepresented the early movement in 2005 as a tilt of 8 degrees to the south and the mechanism as perimeter led.


......................


Ming Wang1; Peter Chang2; James Quintiere3; and Andre Marshall4

1Graduate Research Assistant, Dept. of Civil Engineering, Univ. of Maryland, College Park, MD 20742. E-mail: wming@umd.edu

2Associate Professor, Dept. of Civil Engineering, Univ. of Maryland, College Park, MD 20742. E-mail: pchang@umd.com

3Professor, Dept. of Fire Protection Engineering, Univ. of Maryland, College Park, MD 20742. E-mail: jimq@eng.umd.edu

4Assistant Professor, Dept. of Fire Protection Engineering, Univ. of Maryland, College Park, MD 20742. E-mail: awmarsh@umd.edu

This paper presents an experimental investigation of the World Trade Center Tower 1 (WTC1) collapse using a 1∕20 -scale model. The WTC1 fire on the 96th floor is reconstructed on a small scale, and structural members including the floor trusses and the exterior wall subsystem are built and tested under scaled fire load. Scaling rules are used to determine the values of the insulating material on the structural systems. This experimental study demonstrates the use of scaled models to investigate a real-world fire disaster. Results from the experimental investigation are compared to analytical results and visual evidence compiled in the National Institute of Standards and Technology report on the investigation of the collapse of WTC towers. This study helps engineers and researchers better understand the fire behavior and the associated structural response in WTC1, and a more solidly grounded collapse hypothesis can therefore pursued.


The biggest mistake is to rely on the NIST interpretation of the visual evidence. Best to reconstruct collapse initiation mode from the visual evidence directly. Evidence for core-led failure. No evidence of perimeter led failure. Big difference.



..............................


Graeme Flint1; Asif Usmani2; Susan Lamont3; Barbara Lane4; and Jose Torero5

1Fire Engineer, Arup Fire, 13 Fitzroy St., London, W1T 4BQ, U.K.

2Professor, School of Engineering and Electronics, Univ. of Edinburgh, Alexander Graham Bell Building, The Kind’s Buildings, Edinburgh, Scotland, EH9 3JL, U.K. (corresponding author). E-mail: asif.usmani@ed.ac.uk

3Senior Fire Engineer, Arup Fire, 901 Market St., San Francisco, CA 94103.

4Associate Director, Fire Engineer, Arup Fire, 13 Fitzroy St., London, W1T 4BQ, U.K.

5Professor, School of Engineering and Electronics, Univ. of Edinburgh, Alexander Graham Bell Building, The Kind’s Buildings, Edinburgh, Scotland, EH9 3JL, U.K.

This paper reports on an investigation of the effects of fire on long span truss floor systems in a tall building environment. The effects of fire spread over multiple floors of a building are the focus of this research, especially where this may lead to progressive collapse. The results from an investigation of a two-dimensional model of a multistory office building analysis are presented. The model is representative of the type of construction used in the World Trade Center Towers 1 and 2. The local and global response of the model is described over the course of a concurrent fire on three floors reaching a peak compartment temperature of 800°C . The results of the analysis show that large displacements may occur in long span structural floor systems without failure, however, the interaction of the highly deflected floors with the exterior or perimeter columns can lead to structural collapse. Additional structural members, such as hat trusses, that allow redistribution of loads away from the exterior columns to the core columns have a significant beneficial impact on the robustness of the structure.


Correct mapping of early movement are very useful before modeling a perimeter led collapse, Dr Usmani.





Osama A. Mohamed, P.E., M.ASCE1

1Assistant Professor, Dept. of Civil, Environmental, and Biomedical Engineering, Univ. of Hartford, West Hartford, CT 06117. E-mail: mohamed@hartford.edu

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. The current design standards and building codes provide limited prescriptive or performance-based guidance on analysis or design to guard against progressive collapse. The collapse of the World Trade Center on September 11, 2001, led to demands by the public to amend current building codes and provide protection against collapse caused by extreme events. Following September 11, the literature on progressive collapse mitigation has expanded significantly. Important issues examined by investigators include events leading to progressive collapse, assessment of loads, analysis methods, and design philosophy. This paper seeks to explore aspects of the current state of knowledge on progressive collapse in the technical literature. The paper also discusses loads, structural analysis requirements, and design approaches in United States standards and guides as well as selected international building codes and standards.


The current state of knowledge, especially of the WTC, is *bleep*ty. I would love to hear what you think about a ROOSD model with all the accompanying visual evidence.

No e-mail address. His name is Osama. I'll have to google him.


.........................................


Colin Gurley, P.Eng.1

1Teacher in Civil Engineering, TAFENSW, Sydney Institute of Technology, Ultimo 2007, Australia. E-mail: colin.gurley@bigpond.com; colin.gurley@tafensw.edu.au

This paper follows a companion paper “Progressive Collapse and Earthquake Resistance” (Gurley 2008) dealing with structural design against progressive collapse caused by accidental explosion, terrorist attack, or earthquake. The present paper focuses on those findings/recommendations/implications of the NIST 2005 Final Report on the Collapse of the World Trade Center Towers that relate particularly to proposed changes in structural design practice for fire in tall buildings such as: (1) A new role for, perhaps, a new breed of “fire engineer” as members of building project design teams alongside the established disciplines: architects/structural engineers/HVAC engineers/hydraulic engineers/electrical engineers; (2) a wider role for structural engineers working with fire engineers to carry out structural analysis including fire as a load condition so as to ensure burnout without progressive collapse even if a column is lost and sprinklers fail; (3) more research on sprayed fire resistant materials and better quality control during and after construction “over the life of the building”; and (4) the merits of nonstructural gypsum core walls as opposed to load-bearing concrete cores.


I'd suggest avoiding OOS structures which have led to the largest cascading sets of floor collapses in engineering history. Of course you would not know that unless the collapse progression modes were correctly identified.

I'd also suggest recognizing that sagging floor trusses as an explanation is not supported by the visual evidence. Use correct mappings of early movement or you will be wasting your time.

I look forward to a conversation on the subject.


........................................


Konstantinos Miamis1; Ayhan Irfanoglu2; and Mete A. Sozen3

1School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907. E-mail: kmiamis@purdue.edu

2Assistant Professor of Civil Engineering, School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907 (corresponding author). E-mail: ayhan@purdue.edu

3Kettelhut Distinguished Professor of Structural Engineering, School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907. E-mail: sozen@purdue.edu

The behavior of the World Trade Center Tower 1 on September 11, 2001 is studied in light of experimental data on the effect of elevated temperature on mechanical properties of structural steel. It is concluded that the damage inflicted by aircraft impact on the insulation of the core framing was the dominant factor in the collapse of the structure.


Interesting. They contradict the NIST. Accurate mappings of early movement are vital to determine if you have a point. Do you have accurate records of early movement? I'll send you some.



.....................................


S. M. Marjanishvili, P.E., M.ASCE1

1Hinman Consulting Engineers, Inc., One Bush St., Suite 510, San Francisco, CA 94104.

Following the 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 is high.


Knowledge of ROOSD seems pretty important to what you are doing. Avoid the OOS structures. Of course, you or building owners wouldn't know that since the NIST didn't think it was worth mentioning in their report of how and why the towers collapsed.









Stefan Szyniszewski, Ph.D11Affiliation is not available

Progressive collapse is an increasing concern in the structural engineering community, especially after the collapse of the World Trade Centre Towers. While numerous papers have been published on the subject, the effects of random imperfections on failure paths have not yet been studied. The presented simulation study investigated the effects of random geometric imperfections on the formation of alternative paths after the removal of the first story column(s). Eccentricities and curvatures were introduced as independent random variables for each structural element. Gaussian distributions with means and standard deviations selected on the basis of a handbook of construction tolerances were applied to represent the real life imperfections. The selected, representative seismic building was repeatedly simulated under the same column(s) removal scenario with different imperfections randomly introduced in each simulation. The presented design exhibited competing failure modes. The dominant failure mode was observed in 80% of the simulations, while the secondary failure mode manifested itself in the remaining 20% of the simulations (the same column(s) removal scenario). The presented probabilistic study revealed that real-life imperfections may result in the alternate failure paths. Monte Carlo simulations shall be employed to detect such secondary load redistribution paths and/or collapse modes.


The actual collapse modes of the towers have not been studied. Or rather, they have but only by independent researchers.






More articles



Effect of fire on composite long span truss floor systems[/B], 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
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



Scale modeling of the 96th floor of world trade center tower 1. Wang, M; Chang, P; Quintiere, J, et al. Journal of Performance of Constructed Facilities.


A suggested cause of the fire-induced collapse of the World Trade Towers. Quintiere, JG; di Marzo, M; Becker, R. Fire Safety Journal.


Engineering perspective of the collapse of WTC-I. Irfanoglu, A; Hoffmann, CM. Journal of Performance of Constructed Facilities.


The role of metallurgy in the NIST investigation of the world trade center towers collapse. Banovic, SW; Foecke, T; Luecke, WE, et al. Journal of Mechanics.


Failure of welded floor truss connections from the exterior wall during collapse of the World Trade Center towers. Banovic, S.W; Siewert, T.A. Welding Journal.


Mechanics of the WTC collapse. Cherepanov, G.P. International Journal of Fracture.


Progressive collapse of towers: The resistance effect. Cherepanov, G.P; Esparragoza, I.E International Journal of Fracture.


Impact of the Boeing 767 aircraft into the World Trade Center. Karim, M.R; Fatt, MSH. Journal of Engineering Mechanics.


Structural responses of world trade center under aircraft attacks. Omika, Y; Fukuzawa, E; Koshika, N, et al. Journal of Structural Engineering.


The structural steel of the World Trade Center towers. Gayle, FW; Banovic, SW; Foecke, T, et al. Advanced Materials and Processes.


How did the WTC towers collapse: a new theory. Usmani, AS; Chung, YC; Torero, JL. Fire Safety Journal.


Progressive collapse of the World Trade Center: Simple analysis. Seffen, K. A. Journal of Engineering Mechanics.


Why did the World Trade Center collapse? - Simple analysis. Bazant, ZP; Zhou, Y. Journal of Engineering Mechanics.


How the airplane wing cut through the exterior columns of the World Trade Center. Wierzbicki, T; Teng, X. International Journal of Impact Engineering.


Could the world trade center have been modified to prevent its collapse?; Newland, D. E.; Cebon, D. Journal of Engineering Mechanics.


Why Did the World Trade Center Collapse? Science, Engineering, and Speculation. Eagar, T.W., & Musso, C., Journal of Mechanics.


Dissecting the Collapses. Civil Engineering ASCE.


Elaboration on Aspects of the Postulated Collapse of the World Trade Centre Twin Towers. Clifton, Charles G., HERA: Innovation in Metals.


Stability of the World Trade Center Twin Towers Structural Frame in Multiple Floor Fires. By: Usmani, A. S. Journal of Engineering Mechanics.


The Structural Steel of the World Trade Center Towers. Gayle, Frank W.; Banovic, Stephen W.; Foecke, Tim. Advanced Materials & Processes.


WTC Findings Uphold Structural Design. Post, Nadine M. Engineering News Record.


World Trade Center Collapse-Civil Engineering Considerations. Monahan, B., Practice Periodical on Structural Design and Construction.


Collapse of the World Trade Center Towers: What caused it and what didn't. Bazant, ZP; Benson, D; Greening, F; Le, J.


Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions. Bazant, ZP; Verdure, M.


"TMS Hot Topic Symposium Examines WTC Collapse and Building Engineering" Marechaux, T.G. JOM, v. 54, no. 4, (2002): 13-17.


Abboud, N., M. Levy, D. Tennant, J. Mould, H. Levine, S. King, C. Ekwueme, A. Jain, G. Hart. (2003) Anatomy of a Disaster: A Structural Investigation of the World Trade Center Collapses. In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 360-370


Beyler, C., D. White, M. Peatross, J. Trellis, S. Li, A. Luers, D. Hopkins. (2003) Analysis of the Thermal Exposure in the Impact Areas of the World Trade Center Terrorist Attacks. In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 371-382


Thater, G. G.; Panariello, G. F.; Cuoco, D. A. (2003) World Trade Center Disaster: Damage/Debris Assessment In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 383-392




Another list:


Eagar, T.W., & Musso, C. Why Did the World Trade Center Collapse ? Science, Engineering, and Speculation JOM v. 53 N°12 2001
Clifton, Charles G., Elaboration on Aspects of the Postulated Collapse of the World Trade Centre Twin Towers, Innovation in Metals 2001

Pinsker, Lisa, M. Applying Geology at the World Trade Center Site Geotimes v. 46, no. 11 2001
Zdenek P. Bazant, Yong Zhou Why Did the World Trade Center Collapse ? - Simple Analysis Journal of Engineering Mechanics v. 128 N°1 2002

Anne Powell Dissecting the Collapses Civil Engineering ASCE v. 72 N°5 2002
Quintiere, J.G.; di Marzo, M.; Becker, R. A suggested cause of the fire-induced collapse of the World Trade Towers, Fire Safety Journal v. 37 Issue 7 2002

Newland, D. E.; Cebon, D. Could the world trade center have been modified to prevent its collapse ? Journal of Engineering Mechanics v. 128 Issue 7 2002

Monahan, B. World Trade Center Collapse-Civil Engineering Considerations Practice Periodical on Structural Design and Construction v. 7, no. 3 2002

Brannigan, F.L. WTC: Lightweight Steel and High-Rise Buildings Fire Engineering v.155 no. 4 2002

Fema Construction and Collapse Factors Fire Engineering v.155 no. 10 2002

Corbett, G.P. Learning and Applying the Lessons of the WTC Disaster Fire Engineering v.155 no. 10 2002

Norman J. Glover Collapse Lessons Fire Engineering v. 155 no. 10 2002

Burgess, I.W. Fire Resistance of Framed Buildings Physics Education v. 37 (5) 2002

Marechaux, T.G. TMS Hot Topic Symposium Examines WTC Collapse and Building Engineering JOM v. 54, no. 4 2002

Wierzbicki, T.; Teng, X How the airplane wing cut through the exterior columns of the World Trade Center Journal of Impact Engineering v. 28 2003

Usmani, A. S.; Chung, Y. C.; Torero, J. L How did the WTC towers collapse ? A new theory Fire Safety Journal v. 38 2003

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

Biederman, R.R., Sullivan, E.M., Sisson Jr., R.D., Vander Voort, Microstructural analysis of the steels from Buildings 7, & 1 or 2 from the World Trade Center Microscopy and Microanalysis v. 9 2003

Gayle, Frank W.; Banovic, Stephen W. Tim. Foecke The Structural Steel of the World Trade Center Towers Advanced Materials & Processes v. 162 no10 2004

Nadine M. WTC Findings Uphold Structural Design ENR v. 253 no17 2004

Marjanishvili, S.M. Progressive analysis procedure for progressive collapse Journal of Performance of Constructed Facilities v. 18 (2) 2004

Corley, W.G. Lessons learned on improving resistance of buildings to terrorist attacks Journal of Performance of Constructed Facilities v. 18 (2) 2004

Zhou, Q., Yu, T.X. Use of high-efficiency energy absorbing device to arrest progressive collapse of tall building Journal of Engineering Mechanics v. 130 (10) 2004

Karim, Mohammed R.; Fatt, Michelle S. Hoo Impact of the Boeing 767 Aircraft into the World Trade Center. Journal of Engineering Mechanics v. 131 Issue 10 2005

Usmani, A. S Stability of the World Trade Center Twin Towers Structural Frame in Multiple Floor Fires Journal of Engineering Mechanics v. 131 Issue 6 2005

Omika, Yukihiro.; Fukuzawa, Eiji. Koshika, Norihide Structural Responses of World Trade Center under Aircraft Attacks Journal of Structural Engineering v. 131 no1 2005

Chang, Jeremy; Buchanan, Andrew H.; Moss, Peter J Effect of insulation on the fire behaviour of steel floor trusses Fire and Materials v.29 : 4 2005

Abolhassan, Genady P. Cherepanov September 11 And Fracture Mechanics, a Retrospective International Journal of Fracture v. 132 No. 2 2005

Baum, H.R., Rehm, R.G., Quintiere, J.G. A simple model of the World Trade Center fireball dynamics Proceedings of the Combustion Institute 2005

G. Flint, A.S. Usmani, S. Lamont, J. Torero and B. Lane, Effect of fire on composite long span truss floor systems Journal of Constructional Steel Research v. 62 (4) 2006

Gayle, F.W., Banovic, S.W., Foecke, T., Fields, R.J., Luecke, W.E., McColskey, J.D., McCown, C., Siewert, T.A. The structural steel of the World Trade Center towers Journal of Failure Analysis and Prevention v. 6 (5) 2006

Mohamed, O.A. Progressive collapse of structures: Annotated bibliography and comparison of codes and standards Journal of Performance of Constructed Facilities v. 20 (4) 2006


Zdenek P. Bazant, Mathieu Verdure Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions Journal of Engineering Mechanics v. 133 No. 3 2007

Banovic, S.W., Siewert, T.A. Failure of welded floor truss connections from the exterior wall during collapse of the world trade center towers Welding Journal v. 86 (9) 2007

Gayle, F.W. The collapse of the world trade center towers: A metallurgist's view MRS Bulletin v. 32 (9) 2007

Hansen, B. Building code changes reflect world trade center investigation Civil Engineering v. 77 (9) 2007

Graeme Flint, Asif Usmani, Susan Lamont, Barbara Lane, and Jose Torero Structural Response of Tall Buildings to Multiple Floor Fires Journal of Structural Engineering v. 133 Issue 12 2007

Ayhan Irfanoglu, Christoph M. Hoffmann An Engineering Perspective of the Collapse of WTC-1, Journal of Performance of Constructed Facilities v. 22 No. 1 2008

Keith A. Seffen Progressive Collapse of the World Trade Centre: a Simple Analysis Journal of Engineering Mechanics v. 134 No. 2 2008

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 v. 134 2008

Cherepanov, G.P. Collapse of towers as applied to September 11 events Materials Science v. 44 2008
Kuligowski, E.D., Mileti, D.S. Modeling pre-evacuation delay by occupants in World Trade Center Towers 1 and 2 on September 11 Fire Safety Journal 2008

Kodur, V.K.R. World Trade Center building disaster: Stimulus for innovations Indian Concrete Journal v. 82 2008

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 v. 21 Issue 6

Genady P. Cherepanov Mechanics of the WTC collapse International Journal of Fracture v. 141 No. 1-2

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 v. 30, Issue 5 2008

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 v. 30, Issue 5 2008

Jeom Kee Paik, Bong Ju Kim Progressive collapse analysis of thin-walled box columns Thin-Walled Structures v. 46, Issue 5 2008

Cheol-Ho Lee, Seonwoong Kim, Kyu-Hong Han, Kyungkoo Lee Simplified nonlinear progressive collapse analysis of welded steel moment frames Journal of Constructional Steel Research v. 65 Issue 5 2009

Feng Fu, Progressive collapse analysis of high-rise building with 3-D finite element modeling method Journal of Constructional Steel Research in press 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 2009

Santiago Pujol, J. Paul Smith-Pardo A new perspective on the effects of abrupt column removal Engineering Structures, v. 31, Issue 4 2009

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 v.40, Issue 1 2009

Jinkoo Kim, Taewan Kim, Assessment of progressive collapse-resisting capacity of steel moment frames Journal of Constructional Steel Research v.65, Issue 1 2009






And some conferences:


Lu Xinzheng, Jiang Jianjing Simulation for the Collapse of WTC after Aeroplane Impact International Conference on Protection of Structures 2002

Dr. Arden L. Bement, Jr. “Learning from 9/11: Understanding the Collapse of the World Trade Center” Committee of Science House of Representatives 2002

Abboud, N., M. Levy, D. Tennant, J. Mould, H. Levine, S. King, C. Ekwueme, A. Jain, G. Hart. Anatomy of a Disaster: A Structural Investigation of the World Trade Center Collapses Third Congress on Forensic Engineering 2003

Beyler, C., D. White, M. Peatross, J. Trellis, S. Li, A. Luers, D. Hopkin Analysis of the Thermal Exposure in the Impact Areas of the World Trade Center Terrorist Attacks Third Congress on Forensic Engineering 2003

Thater, G. G.; Panariello, G. F.; Cuoco, D. A. World Trade Center Disaster: Damage/Debris Assessment Third Congress on Forensic Engineering 2003

Choi, S.K., Burgess, I.W. and Plank, R.J. The Behaviour of Lightweight Composite Floor Trusses in Fire Designing Structures for Fire 2003

Venkatash K. R. Kodur Role of fire resistance issues in the collapse of the Twin Towers International Conference on Tall Buildings 2003

Abolhassan Astaneh-Asl World Trade Center Collapse, Field Investigation and Analysis the Ninth Arab Structural Engineering Conference 2003

Mendonça, D., Lee II, E.E., Wallace, W.A. Impact of the 2001 World Trade Center attack on critical interdependent infrastructures IEEE International Conference on Systems 2004

Kuldeep Prasad and Howard R. Baum Coupled fire dynamics and thermal response of complex building structures Proceedings of the Combustion Institute 2005

Jowsey et all Determination of Fire Induced Collapse Mechanisms in Steel Framed Structures 4th European Conference on Steel and Composite Structures 2005

Usmani et all Collapse scenarios of WTC 1 & 2 with extension to generic tall buildings Congress on Fire Safety in Tall Buildings 2006

Marshall, A., Quintiere, J. A collective undergraduate class project reconstructing the September 11, 2001 world trade center fire ASEE Annual Conference and Exposition 2007

Pfatteicher, S.K.A "A new era": The limits of engineering expertise in a post-9/11 world International Symposium on Technology and Society 2007

Razdolsky, L. Fire load in a steel building design 4th International Structural Engineering and Construction Conference 2008

Rini, D., Lamont, S. Performance based structural fire engineering for modern building design Structures Congress 2008




Another list compiled by poster Oystein from this link:


A Bibliography Of Scientific Literature On The World Trade Center Collapse


Studies And Investigations

2002/05 - Federal Emergency Management Agency (FEMA) and the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE) - World Trade Center Building Performance Study - link 1, link 2
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 Architectural Damage; 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 Tower; 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.
2005/09 - National Institute of Standards and Technology (NIST) - Federal Building and Fire Safety Investigation of the World Trade Center Disaster - link
2006/09, 2007/04 - Purdue University, Computer Graphics and Visualization Lab - High-Fidelity Visualization of Large-Scale Simulations - link 1, link 2


Journal Articles

2001
2001/12 - Thomas W. Eagar, Christopher Musso - Why Did the World Trade Center Collapse? Science, Engineering, and Speculation - JOM (Vol. 53, No. 12) - full article

2002
2002/01 - Zdenek P. Bazant, Yong Zhou - Why Did the World Trade Center Collapse? - Simple Analysis - Journal of Engineering Mechanics (Vol. 128, No. 1) - full article
2002/03 - Zdenek P. Bazant, Yong Zhou - Addendum to "Why Did the World Trade Center Collapse? - Simple Analysis"- Journal of Engineering Mechanics (Vol. 128, No. 3) - full article
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
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
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
2006/09 - Genady P. Cherepanov - Mechanics of the WTC collapse - International Journal of Fracture (Vol. 141, No. 1-2)

2007
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
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)
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


Letters

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)


Conference Papers

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


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





Pentagon
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






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









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)




NIST's Investigation of the Sept. 11 World Trade Center Disaster: FAQ (2002: Goals & Methods)





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://forums.randi.org/showthread.php?p=3161860#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
[b]December, 2007[/b]: JOM: The Role of Metallurgy in the NIST Investigation of the Twin Tower Collapses





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 [i]Plumbing Engineer[/i], 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) 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)



Gregory Urich: Detailed Estimate of Mass and Potential Energy of World Trade Center Tower (pdf)






Some Progressive Collapse Studies & Recommendations


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


Some Engineering & physics fundamentals & calculation aids


Shear Force And Bending diagrams 1
Ductile fracture and fragmentation in the reconstruction of the World Trade Center Attack (Wierzbicki)
Elastic Bending Theory




The following individuals and groups participated in the 911 investigations, cleanup and research.
  • 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. /
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

Created on 02/18/2009 07:36 PM by admin
Updated on 02/14/2013 11:35 PM by admin
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