You know we are talking about comparing models with models. If you are not willing to constructively engage the issue, why not find something better to do with your time?
Personally I can't see the point in comparing models and models to be quite honest because all of the models are idealized and don't actually portray what really happened.
This isn't entirely aimed at Gregory, but his post was a useful jumping off point. Throughout the thread I have seen certain models used, but further then people, and in particular the OP (out of ignorance or malaice I won't speculate,) try and apply these models directly to the WTC collapse. Trying to apply a "crush down/chrush up" effect to the WTC won't work because that was an idealised simplification turned into a model, not what actually happened. Going on about whether the columns below or above gave out first during the collapse is pointless,
because the coloumns didn't land on each other. Much of the model vs model "discussions" to me are like two people arguring about whether or not a dropped bowling ball should have gone through the glass top of a coffee table all based on if the legs should have collapsed if the ball had been dropped directly onto one of them.
In the WTC collapses (i.e. once the collapse started) the parts that took the vertical collapse loads were the
floors not the columns. It was the connection points to the columns that determined if the collapse would progress of not, not the column strength. There simply is no way to have trasferred the vertical loading on the floors from the materials falling onto them onto the columns, so the trusses failed at the pin and seated eands, stripping them like you strip a twig of its leaves. The outer shell then had nothing holding it in place and pushed out by the falling debris it peeled outwards breaking into its parts as the stresses of that lean overwhelmed the joins. The floors carried on stright downwards ending up a compacted pile of concrete and steel in and above the basement areas, while parts of the core, after giving way to the pounding of the hat truss for a time, managed to remain standing for a short time after the hat truss gave way resulting in the remaining debries faslling down around the core columns.
This is what we see in the video and pictures of the events, and no it is not as easy to model, but it is what happened, and regardless of the what model you use, it needs to reflect that reality if you are going to attempt toapply it directly to what happened. What models like B&Z and even GU's do is simply show that in the ideal case the towers would have likely fallen, so in the non-ideal case (which we had) there was no way they could possible survive.
