The Progressive Collapse Challenge You've heard that the Twin Towers pancaked, crushing themselves completely. The experts gave us a fancy-sounding term for this: progressive collapse . If you search with the phrase "progressive collapse" you will find numerous articles, most of them written since 9/11/01 about things like assessing and retrofitting existing structures against progressive collapse. It seems that the only examples of progressive collapse of buildings cited are the Twin Towers and the Murrah Federal Building in OKC. A TV documentary which purported to explain the collapses of the Twin Towers featured a demonstration in which a house-of-cards like structure representing one of the towers was supposed to collapse from the top down. The documentary showed only the beginning of this simulated building collapse, since the producers were apparently unable to achieve progressive total collapse. This begs the question: If this newly discovered mode of structural failure is so dangerous, why is it so difficult to reproduce? THE PROGRESSIVE COLLAPSE CHALLENGE !!



The challenge is in 5 parts, from the easiest to the most difficult.



All five require building a structure that will undergo progressive total collapse -- ie: when disturbed near the top, it will crumble from the top down to the bottom, leaving no part standing. The disturbance can include mechanical force, including projectile impacts, and fires, augmented with hydrocarbon fuels such as kerosine. Explosives and electromagnetic energy beams are not permitted.



Your structure can be made out of anything: straws, toothpicks, cards, dominoes, mud, vegetables, pancakes, etc.



The designers of the Twin Towers were able to meet all 5 challenges using steel and concrete.







CHALLENGE #1:



Build an upright structure that will undergo progressive collapse.



CHALLENGE #2:



Build an upright structure with a square footprint and an aspect ratio of at least 6.5 (6.5 times as high as it is wide) that will undergo progressive collapse.



CHALLENGE #3:



Build a structure as required by CHALLENGE #2 which, in the collapse process, will throw pieces outward in all directions such that at least 80% of the weight of the materials ends up lying outside of the footprint, but their center of mass lies inside the footprint.



CHALLENGE #4:



Build a structure as required by CHALLENGE #2 which is also capable of withstanding a 100 MPH wind without collapsing. The structure has to be closed in the sense that it cannot allow air to pass through it.



CHALLENGE #5:



Build a structure that meets the requirements of both CHALLENGES #3 and #4.



