femr2 wrote:Splendid. So do you agree that any debris falling/emerging from the footprint above that point is irrelevant, as the actual point of destruction is lower down in the tower ?
I agree that debris emerging from the footprint is irrelevant in that it is not participating with impact and crushing. However, I feel that it is still relevant with regard to mass and energy considerations. Presumably you have already done calculations and concluded that even with the amount of energy being expended pulverizing concrete and other interior materials, there is still enough energy available in the crush front to cause failure of the columns and sustain a downward acceleration of the crush front. I would expect that the accuracy and validity of these calculations would depend (in part) on the accuracy of estimates of the amount of energy expended in crushing concrete and other materials; and observations of the amount of material being expelled from the building would be considered in making these estimates. Also (and correct me if I am wrong on this), I assume that as mass is lost in the upper portion of the building, the load being experienced by the columns in the lower portion of the building is decreasing; thus increasing the margin between the load that they are experiencing and the maximum load allowed by the factor of safety, and thus making buckling due to overload less likely. Which raises another question: how many buckled columns, due to vertical overload conditions and not horizontal impact, were found in the debris? From what levels did these come?
femr2 wrote:As long as there's enough mass acting at that crush front (which we've worked out to bo about 3 storeys worth) then the rest of the mass (many floors worth by the time of that photo) is not necessary and is quite at liberty to fall out wherever it pleases without affecting the crush front propogation. Yes ?
If the mass is "enough", then yes. Does 3 storys worth of mass apply through the entire height of the building, from top to bottom?
SnowCrash wrote:Why would it be necessary to crush the concrete completely while the only thing the crush front needs to do is secure passage down to the next floors?
It wouldn't be necessary; destroying the column structure is all that is needed to bring the building down. Any energy which goes into pulverizing the concrete likely doesn't assist in bringing the building down; and is probably taking energy away from forces which might otherwise be augmenting the destruction of the column structure.
SnowCrash wrote:This forum has loosely converged around ROOSD (Runaway Open Office Space Destruction), but there is no need to swear allegiance to any Articles of Faith or whatever.
I can visualize runaway collapse down through the office space. As far as I can tell from photographs of the residue, the trusses appear to have been stripped away from the columns rather cleanly and easily, suggesting that those particular connections might have been relatively weak. Whatever force was pushing outward on the perimeter columns (air pressure?) would seem to have been much stronger than the inward pull of the trusses, even while the floors were being impacted by the crush front (as hypothesized). Is this a correct interpretation?
SnowCrash wrote:Your question is a rhetorical one, because you also know that no steel-framed high riser in history has ever progressively collapsed in this manner.
Yes and no. I am aware of the history; but I am also thinking in scientific terms. Sometimes it is necessary to conduct experiments before conclusions can legitimately be drawn; and I think this is one of those instances. Reconstructing whatever portion of the buildings is necessary to test the hypotheses would be a valid science experiment, and would probably cost about the same as a routine NASA mission. The rewards to science and engineering by conducting such experiments would be substantial and well worth the cost, IMHO.
I do not know what brought the buildings down. If I were confident that I did know, I probably wouldn't be here. The reason that I am reading and writing in this forum is because I want to work collaboratively with others to try to figure out what happened. Not to push preconceived theories.
SnowCrash wrote:First off, how would you even know what it would look like, given that it had never happened before?
I don't know what it would look like. Show me, with a verifiable example.
SnowCrash wrote:Second, which controlled demolition can you cite which looks like this?
China conducted a demolition which bore some similarities: http://www.rtve.es/alacarta/videos/television/vuelan-edificio-mas-alto/566780/
SnowCrash wrote:That's because explosives used to cut steel supports don't have the energy to 'push' heavy building components outward like this.
If simply cutting the columns was enough to get things going, explosives wouldn't need to have that much "push" force. The pulverization and expulsions could be a secondary effect of the collapse.
SnowCrash wrote:Should you wish to contend this was achieved with nano-thermite, you ought to explain the low gas expansion velocities, and thus low brisance, achieved by nano-thermite in general, and should you wish to further the notion that the whole building was laced with explosives, then you ought be criticizing AE911Truth for positing only a limited explosive-placing theory utilizing the elevator shafts.
I do not know whether or not nanothermite was involved in the destruction. I do not know whether or not explosives were involved in the destruction, and I am not making any such claim. However, I feel that there is sufficient evidence that it warrants investigation; both here and at a legally authoritative level. If there were thermitic materials involved, they might have been used as incendiary cutter charges rather than explosives. We saw from Jon Cole's demonstration, that when properly focused, even simple home-brew thermite can cut through steel. High-tech stuff might go well beyond the capabilities demonstrated by Cole.
SnowCrash wrote:Besides, after dedicating many, many, many man-hours looking at photos of WTC columns after the collapse, I'm still looking for evidence of column cutting or blast damage caused by something other than plane impact or welding with an oxyacetylene torch.
Do you have an explanation handy for what appears to be trails of white smoke coming from the ends of pieces of steel flying through the air?
SnowCrash wrote:I hope I can make you aware of your burden of proof, and how subconscious attempts to shift said burden can cause one to believe there is a case for controlled demolition, while all there is, is a case for widespread erosion of the physics curriculum.
If you observe me making any unsubstantiated claims, point it out. I want accuracy and verifiability as much as you do.