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Most of the load supported by the failed columns is believed to have transferred to adjacent perimeter columns through Vierendeel behavior of the exterior wall frame. Preliminary structural analyses of similar damage to WTC 2 suggests that axial load demands on columns immediately adjacent to the destroyed columns may have increased by as much as a factor of 6 relative to the load state prior to aircraft impact. However, these exterior columns appear to have had substantial overstrength for gravity loads.
The analysis indicates that most of the loads initially carried by the damaged exterior columns were transferred by Vierendeel truss action to the remaining exterior columns immediately adjacent to the impact area. If the floors at this level are assumed to remain intact and capable of providing lateral support to the columns, this raised the utilization ratio for the most heavily loaded column immediately adjacent to the damage area to approximately a value of 1.0. At a value of 1.0, columns would lose stiffness and shift load to adjacent columns. Based on this analysis, it appears that the structure had significant remaining margin against collapse. However, this analysis does not consider damage to the building core, which was likely significant. Columns located further from the damage area are less severely impacted, and columns located only 20 feet away from the damaged area experience almost no increase in demand at all.
Originally posted by CaptainObvious
Keith Seffen has written a paper for all you math geeks and engineering nerds to read. Please let me know what 90% of those calcualtions mean!!
Griff, Val... I am sure you two will be all over this one!
Originally posted by PepeLapew
I'll tell you what:
Go build a tower in your living room. You can make it out of pizza boxes, LEGO blocks or anything else you want to ..... hell, you can even build it out of a pile of pancakes if you want.......
Then set fire to the top about where the planes would have hit, you can use gasoline or jet fuel for this if you want. You can also throw a rock at it to simulate a plane crash. And watch it.
What you will find is that the progressive collapse or the pancake collapse are both completely impossible to reproduce. Only on that day did 3 buildings fall to the ground straight down onto themselves at the speed of free fall with molten steel found in the basements.
No other time in history has this ever happened, but if it happened 3 times on that day, you surely will be able to reproduce this "progressive collapse" once again?
And BTW, your paper, does it say anything about the existence of the molten steel found in the basements of all 3 buildings?
I bet like every other oh-fishy-all story, the guy pretends that no such steel ever existed.
Dr Seffen has general interests in reconfigurable structures, as described in his research page; other pages can be reached from the navigator list on the left - clicking on "home" restores this page. Please feel free to contact him by 'phone or E-mail or in person.
Dr Seffen is a University Lecturer in Engineering, specialising in Structures, at Cambridge University Engineering Department (CUED). He is a member of the Civil, Structural and Environmental Engineering Division (Division D). He is an Official Fellow of Corpus Christi College, where he has been a Director of Studies, Tutor and Deputy Senior Tutor. Previously, he was a Lecturer in Smart Structures and Materials in the Department of Mechanical Engineering at UMIST (1999-2001, now part of the University of Manchester) and a Research Associate in the Engineering Design Centre at CUED (1997-1999). His PhD (1993-1997) was performed under the supervision of Prof. Pellegrino in the Deployable Structures Group. Keith Seffen read the Engineering Tripos at Cambridge University (1990-1993) and gained a first class degree. He was born, bred and educated in Northern Ireland.
Laboratory for Reconfigurable
Research activities are generally concerned with reconfiguring structural or material form, for synthesising unique, unusual but expeditious properties, to enable, for example, morphing capabilities, large-displacement continuous actuation, ultra-low densities. Click on each of the pictures above for more detail or visit the publications page for specific papers. Dr Seffen is a Chartered Mathematician (CMath), a member of the Institute of Maths and its Applications (IMA) and a member of the American Institute of Aeronautics and Astronautics (AIAA).
Dr Seffen lectures the fourth year modules, Structural Steelwork and Plates and Shells: Theory and Computation. He is also a demonstrator on the Structural Design Course, as well as an examiner throughout the Tripos. Since October 2003, he has been the Director of Studies in Part IA Engineering at Corpus Christi College and he supervises undergraduates in Part IA and IB Structural Mechanics and Mechanics.
F Xu, T J Lu & K A Seffen, "Effect of Thermal Damage on the Compressive Behaviour of Skin Tissue", (2008) Journal of Mechanics in Medicine and Biology, in press
F Xu, T Wen, T J Lu & K A Seffen, "Skin Biothermomechanics Under Medical Treatments", (2008) Journal of the Mechanical Behaviour of Biomedical Materials, in press
F Xu, T J Lu & K A Seffen, "Characterization of Temperature-Dependent Mechanical Behaviour of Skin tissue", (2008) Engineering Letters, in press
F Xu, T Wen, K A Seffen & T J Lu, "Modelling of Skin Thermal Pain - a Preliminary Study", (2008) Applied Mathematics and Computation, in press
K A Seffen,"Progressive Collapse of the World Trade Centre: a Simple Analysis", (2007) ASCE Journal of Engineering Mechanics, in press
F Xu, T Wen, K A Seffen & T J Lu, "Characterization of Thermomechanical Behaviour of Skin Tissue II. Viscoelastic Behaviour", (2007) IAENG (WCE) International Conference of Systems Biology and Bioengineering (ICSBB'07), 2-4 July 2007, London , UK
F Xu, T Wen, K A Seffen & T J Lu, "Characterization of Thermomechanical Behaviour of Skin Tissue I. Tensile and Compressive Behaviours", (2007) IAENG (WCE) International Conference of Systems Biology and Bioengineering (ICSBB'07), 2-4 July 2007, London , UK
A D Norman, S D Guest & K A Seffen, "Novel Multistable Corrugated Structures", (2007) 48th AIAA/ASME/ASCE/AHS/ ASC Structures, Structural Dynamics and Materials Conference, 23-26 April, Hawaii
K A Seffen, "Performance of a Coiled Coil Piezoelectric Bimorph", (2007) Sensors and Actuators A: Physical, 133(2), pp.486-492, DOI: 10.1016/j.sna.2006.04.016
K A Seffen, "Hierarchical Multi-stable Shapes in Mechanical Memory Metal", (2007) Scripta Materilia, 56(5), pp.417-420