Wednesday, March 13, 2013


Tuesday, February 24, 2009

WTC Computer Modeling

Interesting site here that purports to use basic physics to analyze what happened to the WTC-- their model supports demolition:

Tuesday, December 30, 2008

Thursday, November 13, 2008

Interesting Computer Model

Website here.

Physical models are preferable, though!

Sunday, October 19, 2008


Wooden sticks as columns and beams, tape for fastening, and stiff paper for floors. Not shown-- I tried taping steel bolts to the columns to give them more weight to drive a collapse, but the structure fell over before I could finish attaching the extra weight. I removed the bolts before taking the picture.

There is a real problem making a structure that could completely possibly collapse under its own weight, and making a stable structure. I have been trying to make flimsy structures that might collapse, but they won't stay upright long enough to test their collapse response. This thing fell over before I was even done building it.

1) it is impossible to make a stable structure that can crush it's own structure,
2) there is some aspect of scaling down that makes it impossible to make a small stable structure that can crush it's own structure, and that a much larger structure CAN in fact crush it's own structure.

One other potential issue is the difficulty of getting the structural members aligned perfectly with crude fasteners such as tape. If I were able to align the tower more perfectly, it might be more stable-- though I doubt this would overcome the basic problem I described.

Tuesday, July 03, 2007

Latest Attempt (July 2007)

Made a very weak tower model out of paper, with similar design to the WTC towers, with ceramic weights on each floor.

Lower floors had more plies of paper than upper floors.

The tower was unstable and tipped over as one side of the base gave way. The upper part of the tower remained basically intact after falling.

Conclusion-- lower floors have to be VERY strong and stable to support the upper weight of the tower.

Tuesday, January 23, 2007

Someone Else's Attempt at Modeling

Described here.

This part is cool-- he loads it with charcoal and burns his tower.

Here he uses a blowtorch on it

The Progressive Top Down 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, Building 7, and the Murrah Federal Building in Oklahoma City.

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 raises the question: If this newly discovered mode of structural failure is so likely to happen, why is it so difficult to reproduce?


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

All five require building a structure that will undergo top-down progressive total collapse -- i.e.: when disturbed near the top, it will collapse from the top down to the bottom, leaving no part standing. The disturbance can include mechanical force, such as projectile impacts, and fires, augmented with hydrocarbon fuels. 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.


Build a structure with a vertical aspect ratio of at least 2 (twice as tall as it is wide) and induce it to undergo top-down total progressive collapse.


Build a structure with a square footprint and a vertical aspect ratio of at least 6.5 (6.5 times as high as it is wide), and induce it to undergo top-down total progressive collapse.


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


Build a structure as required by CHALLENGE #2 which is capable of remaining intact in 100 MPH cross wind.


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

There IS no precedent for what happened on 9/11 to the twin towers.

So why are so many people here so god-danged bent on declaring it a pure structural-failure "collapse"?