Reply #25: It's very frustrating to continually

[LARED]

question the NIST reports. Putting aside for the moment that common sense tells you that the load should be evenly distributed between the core columns and the perimeter column based on the design, what evidence is there that the reports are tainted. The NIST is not a political arm of anyone. They have been around for a looooong time.

What I do know for sure is if you look in the image I started this thread with, the core of the structure is extremely large and substantial, with thick steel beams, whereas the outer framework appears flimsy in comparison. Granted, that at one particular point on the structure the outer framework may not be very strong but that the combined total of the perimeter could add up to a very strong weight-bearing entity.

First you need to mentally remove the structures that the cranes sit on, as they do not stay in place. The core is in reality not very large and substantial given the size of the WTC. There are something like 47 column spread out over about 10,000 sqft. You need to know that the outer framework was incredibly strong when taken as a whole. (All four sides) It is designed to take the wind loads of at least 100 hundred miles per hour over the surface of the building. This is a huge load, that makes the gravity load look tiny in comparison.

The point is that I can see how the outside structure could break apart during a collapse, but I don't see how the central core will fall apart so readily. In any case, doesn't the pancake model say that the floors rip away from their supporting trusses, and shouldn't this leave the center more or less intact? Granted if enough floors collapse, this could put enough strain on the core for it to eventually topple over or cave in, but this doesn't seem to be the pattern of collapse that happened-- rather everything apparently went at once (in the south tower).

The core had floors, They were slightly thicker than the open area floors. The floors were constructed in a similar fashion. Concrete over joists. The cores was also badly damaged from the impact and fires. One thing you need to consider is when the floors pancake they remove the lateral support of the core columns. Lateral supports are critical for column to remain stable. Without those the column will buckle quickly. As an intact structure the WTC was very strong. The core was, the perimeter was. Once you start removing supports that stiffen the structure it's all over.