Structure Magazine, a well respected magazine for structural engineers, has come out with a probable collapse hypothesis. "Single Point of Failure: How the Loss of One Column May Have Led to the Collapse of WTC 7" points out that the failure of column 79 in the lower levels will create the very effect we see in videos.
http://www.structuremag.org/Archives/2007-11/SF-WTC7-Gilsanz-Nov07.pdf Yet another peer reviewed paper from a respected Journal finds the towers were doomed to collapse.
9/11 demolition theory challenged
An analysis of the World Trade Center collapse has challenged a conspiracy theory surrounding the 9/11 attacks.
The study by a Cambridge University, UK, engineer demonstrates that once the collapse of the twin towers began, it was destined to be rapid and total.
One of many conspiracy theories proposes that the buildings came down in a manner consistent with a "controlled demolition".
The new data shows this is not needed to explain the way the towers fell.
Resistance to collapse
Dr Keith Seffen set out to test mathematically whether this chain reaction really could explain what happened in Lower Manhattan six years ago. The findings are published in the Journal of Engineering Mechanics.
Previous studies have tended to focus on the initial stages of collapse, showing that there was an initial, localized failure around the aircraft impact zones, and that this probably led to the progressive collapse of both structures.
In other words, the damaged parts of the tower were bound to fall down, but it was not clear why the undamaged building should have offered little resistance to these falling parts.
"The initiation part has been quantified by many people; but no one had put numbers on the progressive collapse," Dr Seffen told the BBC News website.
Dr Seffen was able to calculate the "residual capacity" of the undamaged building: that is, simply speaking, the ability of the undamaged structure to resist or comply with collapse.
His calculations suggest the residual capacity of the north and south towers was limited, and that once the collapse was set in motion, it would take only nine seconds for the building to go down.
This is just a little longer than a free-falling coin, dropped from the top of either tower, would take to reach the ground.
He added that his calculations showed this was a "very ordinary thing to happen" and that no other intervention, such as explosive charges laid inside the building, was needed to explain the behavior of the buildings.
The controlled detonation idea, espoused on several internet websites, asserts that the manner of collapse is consistent with synchronized rows of explosives going off inside the World Trade Center.
This would have generated a demolition wave that explained the speed, uniformity and similarity between the collapses of both towers.
Conspiracy theorists assert that these explosive "squibs" can actually be seen going off in photos and video footage of the collapse. These appear as ejections of gas and debris from the sides of the building, well below the descending rubble.
Other observers say this could be explained by debris falling down lift shafts and impacting on lower floors during the collapse.
http://news.bbc.co.uk/2/hi/science/nature/6987965.stm Dr. Keith A. Seffen
http://www.eng.cam.ac.uk/~kas14/ Below is the list of people who have staked their reputations on the only paper which passed the scrutiny of peer review regarding the WTC tragedy...
For those who may think that no one has written a peer reviewed paper on the collapse of the towers here it is...
"Walter P. Murphy Professor of
Civil Engineering and Materials Science
Northwestern University
The towers of the World Trade Center were designed to withstand as a whole the horizontal impact of a large commercial aircraft. So why did a total collapse occur? The reason is the dynamic consequence of the prolonged heating of the steel columns to very high temperature. The heating caused creep buckling of the columns of the framed tube along the perimeter of the structure, which transmits the vertical load to the ground. The likely scenario of failure may be explained as follows...
http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf The version linked above, to appear in the Journal of Engineering Mechanics (ASCE), was revised and extended (with Yong Zhou on September 22 and additional appendices on September 28) since the original text of September 13, which was immediately posted at various civil engineering web sites, e.g. University of Illinios. It also has been or soon will be published in a number of other journals, including Archives of Applied Mechanics, Studi i Ricerche, and SIAM News:
Z. P. Bazant and Y. Zhou, "Why Did the World Trade Center Collapse?", Society for Industrial and Applied Mathematics News, vol. 34, No. 8 (October, 2001).
That means it's not just a document, book, web site or calculation on a forum. It's had to pass critical review by other engineering Professors.
I know there are CT sites which attack this paper but not one person has yet to disprove its hypothesis professionally. There are still people attacking the theory of evolution. Anyone can attack, not many can produce a paper to back it up. Just as there is no "theory of intelligent design" except on Christian web sites, there are no alternatives to this paper other than in CT sites and books."
http://www-math.mit.edu/~bazant/WTC/ The paper...
http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf http://www.pubs.asce.org/journals/edem.html Editor:
Ross B. Corotis, Ph.D., P.E., S.E., NAE, University of Colorado, Boulder
corotis@colorado.edu
http://ceae.colorado.edu/new/faculty/people/people.cgi?corotis Editorial Board:
Younane Abousleiman, Ph.D., University of Oklahoma
http://mpge.ou.edu/faculty_staff/faculty.htmlChing S. Chang, Ph.D., P.E., University of Massachusetts
http://www.ecs.umass.edu/cee/faculty/chang.htmlJoel P. Conte, Ph.D., P.E., University of California, San Diego
http://kudu.ucsd.edu/Henri Gavin, Duke University
http://www.cee.duke.edu/faculty/gavin/index.phpBojan B. Guzina, University of Minnesota
http://www.ce.umn.edu/people/faculty/guzina/Christian Hellmich, Dr.Tech., Vienna University of Technology
http://whitepages.tuwien.ac.at/oid/998877.htmlLambros Katafygiotis, Ph.D., Hong Kong University of Science and Technology
http://lambros.ce.ust.hk/Nik Katopodes, Ph.D., University of Michigan
http://www.engin.umich.edu/dept/cee/prospective/Nicos Makris, University of Patras
http://www.civil.upatras.gr/Melidep_gr/depi_en.asp?profid=5Robert J. Martinuzzi, P.E., University of Calgary
http://www.ucalgary.ca/pubs/calendar/2005/who/stafflists/academicAlpha.htmArif Masud, Ph.D., University of Illinois, Chicago
http://www.uic.edu/depts/bioe/faculty/core_faculty_list.htmArvid Naess, Ph.D., Norwegian University of Science and Technology
http://www.bygg.ntnu.no/~arvidn/front.htmKhaled W. Shahwan, Daimler Chrysler Corporation
http://www.pubs.asce.org/WWWdisplay.cgi?9800592George Voyiadjis, Ph.D., EIT, Louisiana State University
http://www.cee.lsu.edu/facultyStaff/Voyiadjis_George/Voyiadjis_Gbio.htmYunping Xi, Ph.D., University of Colorado
http://ceae.colorado.edu/new/faculty/people/people.cgi?xi Engineering Mechanics Division Executive Committee
Alexander D. Cheng, Ph.D., M.ASCE, Chair
http://home.olemiss.edu/~acheng/James L. Beck, Ph.D., M.ASCE
http://www.its.caltech.edu/~jimbeck/Roger G. Ghanem, Ph.D., M.ASCE
http://ame-www.usc.edu/personnel/ghanem/index.shtmlWilfred D. Iwan, M.ASCE
http://www.eas.caltech.edu/fac_i-m.html#iChiang C. Mei, M.ASCE
http://cee.mit.edu/index.pl?id=2354&isa=Category&op=showVerna L. Jameson, ASCE Staff Contact
Journal of Engineering Mechanics
More links to civil engineering papers and other information concerning the WTC collapse...
Bazant, Z.P., & Zhou, Y.
"Addendum to 'Why Did the World Trade Center Collapse? - Simple Analysis" (pdf)
Journal of Engineering Mechanics v. 128, no. 3, (2002): 369-370.
Brannigan, F.L.
"WTC: Lightweight Steel and High-Rise Buildings"
Fire Engineering v.155, no. 4, (2002): 145-150.
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.
"Construction and Collapse Factors"
Fire Engineering v.155, no. 10, (2002): 106-108.
Corbett, G.P.
"Learning and Applying the Lessons of the WTC Disaster"
Fire Engineering v.155, no. 10, (2002.): 133-135.
"Dissecting the Collapses"
Civil Engineering ASCE v. 72, no. 5, (2002): 36-46.
Eagar, T.W., & Musso, C.
"Why Did the World Trade Center Collapse? Science, Engineering, and Speculation"
JOM v. 53, no. 12, (2001): 8-12.
Federal Emergency Management Agency, Therese McAllister, report editor.
World Trade Center Building Performance Study: Data Collection, Preliminary Observations, and Recommendations
(also available on-line)
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.
"Collapse Lessons"
Fire Engineering v. 155, no. 10, (2002): 97-103
Marechaux, T.G.
"TMS Hot Topic Symposium Examines WTC Collapse and Building Engineering"
JOM, v. 54, no. 4, (2002): 13-17.
Monahan, B.
"World Trade Center Collapse-Civil Engineering Considerations"
Practice Periodical on Structural Design and Construction v. 7, no. 3, (2002): 134-135.
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.
National Instititue of Stamdards and Technology: Congressional and Legislative Affairs
“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.
Pinsker, Lisa, M.
"Applying Geology at the World Trade Center Site"
Geotimes v. 46, no. 11, (2001).
The print copy has 3-D images.
Public Broadcasting Station (PBS)
Why the Towers Fell: A Companion Website to the Television Documentary.
NOVA (Science Programming On Air and Online)
Post, N.M.
"No Code Changes Recommended in World Trade Center Report"
ENR v. 248, no. 14, (2002): 14.
Post, N.M.
"Study Absolves Twin Tower Trusses, Fireproofing"
ENR v. 249, no. 19, (2002): 12-14.
The University of Sydney, Department of Civil Engineering
World Trade Center - Some Engineering Aspects
A resource site.
"WTC Engineers Credit Design in Saving Thousands of Lives"
ENR v. 247, no. 16, (2001): 12.
