Charlie Bell wrote: > On 29/06/2006, at 9:18 PM, Gibson Jonathan wrote: >> I do believe the soft-butter theory could have some merit and look >> forward to real studies we can sink teeth into and chew properly. >> As I understand it Underwriters Labs put the original steel, and >> debris samples, under 2,000° for several hours without deformity > > I take it you mean 2000F, around 1100C. You can heat steel to that > temperature, it will not melt or deform. What it does do is become > about half as strong, and will bend, stretch and fail if it's > structural. Not to forget that a lot of the central support had just > had a plane fly into it. > >> I have yet to see a model - or even discussion - on how such metal >> is a renowned heat wick and just how this would have mitigated >> total systemic collapse... unless the argument is that this >> apparently minimal heat was X-ferred down the entire skeleton >> structure... leading to the "Soft Butter" support member lack of >> resistance that allowed the entire building to fall at damn-near >> free-fall speeds - all at once. > > It didn't collapse all at once. It was jackhammered floor by floor. > it only needed the top 1/4 of the building to start collapsing to > crush the rest. > > I'm amazed that this is at all mysterious. > I think what Jonathan is refering to is the idea that "jackhammered floor by floor" is not consistant with "freefall". The floors below, even though they give way should present a bit of resistance that slows the fall. The idea incorporates the fact that the floors below were not weakened by fire, but maintained their integrity until hammered kineticly.
I can't say that I know much about this aspect, but my intuition tells me that the structure below should give more resistance than vacuum or air.<G> OTOH, the shock that is transmitted though the structure by the pounding from above would significantly overpressure the shear strength of the bolts that tied the horizontal structure to the vertical structure. Does anyone know if there was welding performed in addition to bolting? Or would that inhibit the neccessary flexing required of such a tall structure? xponent Spasms Maru rob _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
