06-08-2013, 05:05 AM
Tony Szamboti Wrote:Now not only does there have to be a dynamic load to start the column yielding, but there has to be enough kinetic energy available to completely collapse the column, because as the column deforms it absorbs energy, and in the case of large steel columns lots of it. The fall of the upper section of the North Tower should not have progressed, because the column energy absorption capacity was significantly greater than the kinetic energy that was available. In other words, there wasn't enough energy available to break through the columns after a one or even two story drop.
Is it possible the inner core/outer frame structure caused a lateral force that was exacerbated by the floor platforms falling into the void caused by this lateral shift and ensuing removal of the floor platform supports that caused an unexpected massive kinetic force that drove the collapse of the inner core therefore defeating the expected resistance models you cite? In other words the resistance wasn't there because the outer frame and inner core both shifted away from the floor supports causing that mass to plunge unobstructed therefore causing the force it would have taken to overcome the column energy absorption you cite? When those inner core columns were compromised by that lateral force they would no longer possess the vertical resistance you cite. This failure would be almost instantaneous and not possess the expected deceleration you cite.
And what about the South Tower?