I'd suggest <1s as, if you recall, the NIST values suffered from their misinterpretation of early motion around the highlighted pixel...The roof line descended for about 1.7 seconds previous to near freefall.
...amongst other technical problems with their tracing process, discussed in detail elsewhere.
The columns ? What columns ? All columns ?This would be the first stage during the time where the columns buckled.
ftfyHowever. we know from thecollapsedescent of the East penthouse about 7 seconds before thebuildingvisible North and West building facades reached near freefallcollapseacceleration that a section of the core had failed and removed the lateral restraint for some of the exterior columns.
Isn't it about time you stopped ignoring everything you've learned that contradicts (or improves upon) your bible ?