Do you think it is at all possible that significant amounts were in the perimeter columns? I think we would have seen the extremely bright light if burning thermite had made it out of the perimeter columns.
I think we established that RJ Lee thinks most of the cooked-off lead was in the computers.
How could thermite inside the columns have cooked of lead in the open offices? You hopefully are aware that thermite, while able to reach extreme temperatures locally for a very short time, contains surprisingly little heat (energy) and could therefore not project that temperature over serious distances or for long enough time to melt columns AND vaporize computers?