Uploaded September 2019 | Updated September 2026, 15 hours ago
Now that Dr Leroy Hulsey from the University of Alaska Fairbanks has released his simulation work from the past four years and people are flooding my comment sections sharing it, I have decided to make a short video showing why it is inferior to the NIST simulations.
By visualizing the dynamic motion of the structure from the color change of the pixels it is possible to see even very small (subpixel) deformations. You'll notice that the building in the UAF simulations is not moving at all even when the "penthouse" is crashing down. No motion means that there is no dynamic response (no propagation) of the initial impulse observable within the structure. This would be highly unlikely in reality but confirms the observation that parts of the structure are allowed to intersect each other without collisions. It can be concluded that resistance is completely ignored within the UAF simulations, which makes them questionable and inferior to the NIST simulations.
But how does it work? In reality and in FEA simulations forces will lead to displacements. Pixel colors allow to detect even very small displacements because of aliasing. This doesn't mean that this visual data is comparable to FEA data, it's obviously not, but it's more than enough to detect if there is any displacement. The point of this video is not to derive accurate data from pixels but to detect if there is any data at all. Zero pixel changes mean zero forces, or basically an invalid simulation.
Mick West made a longer video dissecting the sims in more detail: youtube.com/watch?v=7OClixCTdDw
Original UAF videos: http://ine.uaf.edu/wtc7
Now that Dr Leroy Hulsey from the University of Alaska Fairbanks has released his simulation work from the past four years and people are flooding my comment sections sharing it, I have decided to make a short video showing why it is inferior to the NIST simulations.
By visualizing the dynamic motion of the structure from the color change of the pixels it is possible to see even very small (subpixel) deformations. You'll notice that the building in the UAF simulations is not moving at all even when the "penthouse" is crashing down. No motion means that there is no dynamic response (no propagation) of the initial impulse observable within the structure. This would be highly unlikely in reality but confirms the observation that parts of the structure are allowed to intersect each other without collisions. It can be concluded that resistance is completely ignored within the UAF simulations, which makes them questionable and inferior to the NIST simulations.
But how does it work? In reality and in FEA simulations forces will lead to displacements. Pixel colors allow to detect even very small displacements because of aliasing. This doesn't mean that this visual data is comparable to FEA data, it's obviously not, but it's more than enough to detect if there is any displacement. The point of this video is not to derive accurate data from pixels but to detect if there is any data at all. Zero pixel changes mean zero forces, or basically an invalid simulation.
Mick West made a longer video dissecting the sims in more detail: youtube.com/watch?v=7OClixCTdDw
Original UAF videos: http://ine.uaf.edu/wtc7
