NO! "they don't base" this FFA on anything but the OBSERVATIONS. The simulations are not explanations of WHY the frame / building did what it did... but supposedly the sequence of the "behavior" of the frame....with no explanation given explaining the movements.I agree this is somewhat veering off-topic, but I don't want to not reply to something I find interesting to talk about just because it's technically off-topic. And it is still related... The thread is about NIST claiming that buckling explains why the roofline of the building appeared to be in free fall acceleration for about 2.25 seconds. They base this on their simulations, stating:
My question was, how do we know the simulations to be accurate? As with anything, trust should be proportional to transparency. And my trust that NIST got it right would be greatly increased if all their simulation files were publicly released. Because they're not, we depend on their say-so.
It's basic engineering or physics that something such as a facade of a building falls DOWN because it loses axial support.
The NIST simulation seems incorrect... but it does show total destruction. NIST showed a total collapse... something that people thought could not happen. We know it collapsed because we saw it. NO ONE NEED a simulation.
What would be more useful would be a series of force diagrams showing the forces in the frame in small increments of time from static to collapsing.