NOTE: See this more recent version of this article.

9 - 1 1 R e s e a r c h

an attempt to uncover the truth about September 11th 2001
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Before the Committee on Science of the U.S. House of Representatives

March 6, 2002 Hearing on

"Learning from 9/11: Understanding the Collapse of the World Trade Center"

It is a great honor for me to testify here today and address specific questions (in blue below) listed in your letter regarding my involvement in the post disaster investigation of the World Trade Center.

What role did you play in the investigating the collapse of the WTC buildings and what do you expect to produce from your effort? How did you arrange NSF funding for your work, and how was that arranged so quickly?

My involvement in the investigation of the collapse of the World Trade Center is to conduct a reconnaissance of the collapsed and damaged WTC buildings and to collect the perishable data. The main objectives of the reconnaissance are to learn as much as possible from the actual collapsed structures and to document the failure modes and performance of the members and connections as well as quality of the construction. The purpose of collecting the perishable data is to collect material samples, photographs, videotapes, drawings and data on design, construction and collapse. Using the information collected and by conducting the necessary analyses and research, we try to establish probable causes of the collapse and most likely scenario for such collapse.

Our project was funded by the Directorate of Engineering of the National Science Foundation as one of the eight Quick Response Research Awards in the aftermath of the WTC collapse. These projects focus on structural engineering (our project at UC-Berkeley), fire engineering, social aspects and response and recovery. More information on these projects can be found at We prepared and submitted our proposal to the National Science Foundation three days after the 9/11 events and it was reviewed and funded by the end of the week. The credit for such a fast preparation, submittal, review and funding of these research projects should be given equally to the staff at the universities involved as well as the Program Directors and staff of the National Science Foundation. The use of "Fastlane" electronic submittal process of the NSF also expedited the process tremendously.

So far, I have made three trips to NYC and spent a total of about 25 days there conducting field investigation and collecting data. Upon arrival to NYC on September 19, and after visiting Ground Zero and paying my respects and prayers to the victims, I started my reconnaissance and collection of the perishable data. I have collected some data on design and construction of the WTC and have met and discussed the case with the structural engineers who have designed the WTC Buildings. Thanks to cooperation of the HSNE recycling plant, I have been able to study the steel from the WTC before recycling. I have identified and saved some components of the structures that appear to have been subjected to intense fire or impact of fast moving objects. Figures 1 through 4 show examples of inspected structures. These critical pieces are saved as perishable data and can be used in future research.

Full-size images of these four photographs are available at:

Figure 1.
Figure 2.
Figure 3.
Figure 4.

Please describe the impediments that you encountered during the investigation of the collapse of the WTC buildings, such as the loss of material from the WTC site and any effects of such impediments on your work.

I wish I had more time to inspect steel structure and save more pieces before the steel was recycled. However, given the fact that other teams such as NIST, SEAONY and FEMA-BPAT have also done inspection and have collected the perishable data, it seems to me that collectively we may have been able to collect sufficient data. The main impediments to my work were and still are:
  1. Not having a copy of the engineering drawings and design and construction documents.
  2. Not having copies of the photographs and videotapes that various agencies might have taken during and immediately after the collapse.

Such data has already been made available to ASCE Building Performance Assessment Team. If those are also available to us, we will be able to proceed further with our research. Figure 5 shows an example of analysis of performance of generic steel high-rise structure subjected to the impact of a 747 jetliner and the ensuing fire. The example demonstrates the power of advanced technology developed in aerospace and mechanical engineering that can be brought to bear on this problem. We plan to use the drawings and the data and the software used in the example to build a computer based realistic model of the World Trade Center towers and analyze their response to simulated impact of the 767 planes that crashed into them on 9/11 and the ensuing fire.

For more on the simulation of a Boeing 747 hitting the WTC, click here.

Should the Federal Emergency Management Agency (FEMA) and/or Congress develop a more comprehensive protocol for how to conduct investigations in response to natural disasters and/or terrorist attacks?

The earthquake engineering community has conducted post disaster investigations very successfully and systematically within the Earthquake Engineering Research Institute and funded by NSF and FEMA for several decades. As a result of such post-disaster investigations, the lessons learned and the continued research and technology developments, great advances have been made in mitigating earthquake hazard. The approach taken in earthquake engineering can equally be applied to investigation of damage due to terrorist attacks as well as to minimizing consequences of such attacks. Due to the criminal nature of terrorist attacks and the higher priority placed on criminal investigation, over engineering investigation, it appears that there is a need for a protocol to govern the availability of information and access to the site as well as interaction of the crime investigators and researchers investigating the scientific and engineering aspects of the terrorist attacks.

What areas of research into the WTC collapse still need to be addressed, and what is the most appropriate way to handle these needs?

There are short term and long-term research needs into the WTC collapse. In the short term, there is a need for a comprehensive, in-depth and research-oriented study of the WTC buildings, from the time of plane impact, through the ensuing fire and the final collapse. Such studies should not only focus on structural, and fire, engineering aspects, but also on the social and human aspects of the tragedy as well. A broad based team of researchers and engineers from academia, government agencies and the private sector, with expertise in various aspects of the problem, need to be assembled to conduct such studies. In my opinion, such studies need to be directed by federal entities such as the National Science Foundation (NSF) and/or the National Institute of Standards and Technology (NIST) that are involved in directing and conducting scientific and engineering research. In December, the National Science Foundation sponsored a workshop organized by the Institute for Civil Infrastructure Systems of New York University, to identify research needs for future research related to WTC. A list of workshop recommendations can be found at I participated in the workshop and feel that funding research in those areas will result in learning many valuable lessons from this tragedy and will result in significant improvements in the structural design, construction, fire protection, evacuation, fire fighting, rescue and recovery efforts, debris removal and many other aspects of the protection of buildings and occupants against terrorist attacks.

In the long term, there is a need for major and sustained funding to conduct basic and applied research on various aspects of terrorist attacks. Such research activities can result in development of scientific methods and technologies to assure life safety, prevent catastrophic collapses and massive loss of life and minimize the impact of such attacks on the national economy and security. Last month, NIST held a workshop to identify research needs related to evaluation of performance and protection of buildings during intense fires. I also participated in this workshop and feel that the research areas identified at the workshop are very important in providing engineers and architects with the technologies to protect tall buildings, their occupants and firefighters and rescuers against catastrophic fires and resulting collapse.

In the aftermath of 9/11 tragedy and the hazard posed by terrorist attacks to public safety and the economical well being of the U.S. is not much different than the hazard posed by other "extreme events" such as the major earthquakes three or four decades ago. In the case of seismic hazard mitigation, Congress, by providing sufficient funding to the National Science Foundation and other agencies involved, has enabled research and engineering community to develop efficient and economical technologies to mitigate seismic hazard and to prevent catastrophic loss of lives. To prevent catastrophic consequences of terrorist attacks, we need to develop and fund a long-term plan of research, perhaps modeled after seismic research programs developed and supported over the years by NSF and FEMA, and in the field of protection of the building environment against terrorist attacks.

Has the confidential nature of the FEMA's Building Performance Assessment Team investigation made it more difficult to gain access to materials that might be useful, such as private videotapes?

I have not been provided with the information made available to the FEMA Building Performance Assessment Team. This includes, videotapes and photographs taken on 9/11and the following days and copies of the engineering drawings. At this time, having the videotapes, photographs and copies of the drawings not only is useful, but also is essential in enabling us to conduct any analysis of the collapse and to formulate conclusions from our effort.

I have been the Principal Investigator in conducting research on damage and collapse of several major buildings and bridges in the aftermath of earthquakes. I understand and respect the concerns of owners, designers, builders and those who are responsible for safe operation of these structures for possible legal ramifications of findings of our research investigations. However, the main objective of our research is to understand how the WTC buildings failed and learn lessons that can be used to prevent such collapses in the future. Never before have my research results been used in any legal proceedings. However, to allay any concerns that any findings of our research project might increase the liabilities of the City, Port Authority or Silverstein, the data on these structures could be provided to the Principal Investigator (myself) on a propriety basis. The Principal Investigator would keep the data and provide the other members of the research team with the information on a need-to-know basis. I have followed similar procedures to the satisfaction of parties involved in conducting research on major buildings and bridges subjected to earthquakes and blasts due to terrorist attacks. I would like to take this opportunity and thank Chairman Boehlert and members of the Committee on Science for inviting me to testify. I would like now to welcome any questions that you may have.

Abolhassan Astaneh-Asl, Ph.D., P.E.

Department of Civil and Environmental Engineering
781 Davis Hall, University of California, Berkeley, CA 94720-1710
e-mail:, Phone: 510/642-4528

EDUCATION: M.S.E. (1979) and Ph.D. (1982) from the University of Michigan, Ann Arbor

CURRENT POSITION: Professor, University of California at Berkeley.

PROFESSIONAL MEMBERSHIP: American Society of Civil Engineers (ASCE), Council on Tall Buildings and Urban Habitat (CTBUH), Earthquake Engineering Research Institute (EERI), Structural Stability Research Council (SSRC), Research Council on Structural Connections (RCSC), Consortium of Universities for Research in Earthquake Engineering (CUREE), Advisory Committee AC4 and Technical Committee TC8 of Eurocode Europe, Structural Engineers Association of Northern California, (SEAONC), Structural Steel Educational Council, (SSEC), Committee on Design of Blast-Resistant Steel Structures (AISC)

PROFESSIONAL REGISTRATION: Registered Professional Engineer, P.E. (California)

MAJOR AWARD: Winner of 1998 ,T.R. Higgins Award, American Institute of Steel Construction

TEACHING: Has taught courses since 1982 on Engineering Mechanics, Static, Design of Steel Structures, Advanced Steel Design, Design of Steel and Composite Structures, Inelastic Behavior and Plastic Design of Steel Structures, Comprehensive Design of Structures. He has also taught a number of short courses to professionals on design of structures and earthquake engineering particularly on bridges to Caltrans engineers and others.

  1. "Tests of Critical members of the Golden Gate Bridge", (Funded by Golden gate Bridge), 95-96
  2. "Shake-table Tests of Computers with and without Support Restrainers", 96-97.
  3. "Cyclic Behavior and Seismic Design of Steel Piles", (Funded by Caltrans), 96-98.
  4. "Nonlinear Analyses of the Suspension Spans of the Bay Bridge", (Funded by LLNL & UCB, 95-98.
  5. "Seismic Behavior and Design of Shear Connections", (Funded by FEMA/SAC), 97-98.
  6. "Cyclic Tests and Seismic Design Provisions for Steel Shear Walls", (Funded by GSA),99-01.
  7. "Cyclic Tests of Traditional and Innovative Composite Shear Walls", (Funded by NSF) 98-present.
  8. "Testing and Studying Blast-Resistant Structures", (Funded by GSA and AISC) 97-present.
  9. "Studies of Collapse of the World Trade Center", (Funded by NSF) ,01-present

Has published more than 150 papers, reports and other publications on the behavior and design of steel structures subjected to seismic, gravity and blast loads.

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This above link has only displayed its images once in the times I have visited it. I was certainly pleasantly surprised to be able to see (and copy) the images. However, on the next visit the images were missing yet again. It seems someone "accidently" breaks the links, someone fixes them, someone breaks them again,....

This article was once was available as a pdf-document at Files/Astaneh-Testimony Congress-March 6 Final.pdf, but the conspirators have been hard at work (as usual) and the link is now broken (as, in fact, is Professor Astaneh-Asl's entire UC Berkeley web-page).

Home Page (an assortment of articles on September 11 and Palestine).

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