Secondly, I think this may be a flaw with the software, but the sudden impact of the top section on the lower section overloads the columns near ground level. I think this is not realistic, but I guess in real life the whole lower section was obscured by dust so it was difficult to see what exactly was going on down there.
Other than the lack of peeling away of exterior columns, this is another feature I noticed that doesn't seem like the actual collapses. In the actual collapse, even as the first exterior columns and dust was reaching the ground, the lobby level still looked intact and did not appear to be coming apart, nor did the exterior columns above the lobby level but below the present region of the downward cascading floors (as the still from 1:14 to 1:21 in the following video of the south tower collapse from Liberty Street shows):
Similarly see the still at 2:19 in the same video for the north tower, where the lower section is still relatively intact as the first debris and dust is reaching the ground
From the eventual WTC debris pile, notable areas of exterior perimeter columns at the lobby level were left standing (for the north and northeast side of the north tower and for the west and southwest side of the south tower). Had the lower exterior columns begun to collapse before the collapse front reached this region, I don't see how significants sections of above ground exterior perimeter columns near the lobby level can remain standing on certain sections of the building. Yet from the eventual WTC debris pile, this was what was seen.
There didn't appear to be any breakup of the exterior columns (other than emission of dust from broken windows) until the region of downward cascading floors had reached the floor height of those exterior columns.
We're any simulations done by NIST of the fires? And in particular, the affect of wind on the fires at 1000ft?
There were extensive simulations down by NIST of the fire spread and the effect of this on the expected temperature of the steel columns and trusses in the region of fire. If I'm remembering right, this was the part of the research that proved that the steel in the region of fire was heated sufficiently enough to soften and buckle, although not melt.
See Section 6.10 (starting on page 121), Section 6.12 (starting on page 131) and Section 6.14.5 (page 146) specifically in the paper for information on the fire simulations carried out.
A summary of the research done for the reports of both the causes of the collapse of the twin towers and WTC 7 was released shortly before the 20th anniversary of 9/11:
I don't think the effect of wind on the fires was examined in detail other than the researchers at NIST saying that the broken windows (from the plane impact and explosion) helped continue to fuel the fires that were burning because oxygen from outside was able to reach the fires that way.
You can clearly see there must have been a reasonably strong North Westerly wind by the smoke pattern. This would have created a furnace type effect and would have caused the fires to be more severe in the South and East sides. In fact I think this is backed up by the images of 1WTC South facade just before collapse which appear deformed, and also by the people who were seeking refuge in the North Western corner which must have been the coolest place.
I think part of the reason the fires were most severe on the south and east sides at the time of collapse of the north tower is because the fires started more on the north face of the building (the area of the floor where the airplane had first made impact and the fuel in the wings had spilled and ignited) and moved over time to the opposite face on the south side of the building.
Similarly, at the time of collapse of the south tower, the flames from the fires were most visible and intense on the east and north faces of the building, even though the airplane and fires had initially started more on the south face of the building where the airplane had first made impact and the fuel in the wings had first spilled and ignited.
It appears that the fires moved over the floor area to the side opposite of the impact hole as the supply of combustible fuel in a particular floor section of the building that was ignited earlier became exhausted. This would have probably happened first for the area of the floor closest to the initial airplane impact.
Breaking complex things down into separate building blocks is a sound, proven teaching technique. I'm aware that it may not suit some members. If other members also show no interest in comprehending the physics which is the foundation of the OP proposed simulation - I won't press the matter further.
I doubt there is much difference in the practical aspects. The big and unresolved issue with physical models or simulations is in the presumption that they will benefit a large number of persons who would not be sufficiently helped by other methods of teaching/learning. The actual mechanism of the initiation stage of Twin Towers collapses cannot be accurately modeled or simulated in detail. So, whether sim or model, it would have to be a simplified demo of the main principle.
BTW you don't need 22,000 objects to comprehend the real event. Sub-set the tower into a handful of sub-systems. maybe a dozen parts in a sub-system to illustrate principles. The reality of 22,000 objects is actually one of the main reasons FEA analysis of the whole system is impractical.
So from what you are saying, even a physical model (such as pasta columns and wooden blocks or wax columns and wooden blocks) still wouldn't capture the intricacies of the collapse of the towers (presumably because of the necessary small scale of those physical models if designed by a layperson without significant financing) and so a more simple computer model with a sub-system of blocks would have to do, since FEA cannot be run on a large number of blocks without very high computing power?
Why is it that the impact of a plane on a building can't be easily simulated in a physics simulation from Besiege (per discussion in https://www.metabunk.org/threads/ho...ngs-penetrate-the-wtc.3326/page-5#post-259628
) but a collapse of a WTC-like building can?