Originally Posted by moorea34
Or only 3 times? I was fascinated by: quote
Remember that the outer core columns are extremely solid, e.g. no. 501. It is an H-beam with two flanges 17x3.5 inch connected by a 2.2x12.6 inch web. In metric terms the flanges are 430x90 mm and the web is 56x320 mm. Such thick plates, 56 and 90 mm cannot buckle under any circumstance when the compressive stress is only 30% of yield stress, even if the temperature is 500°C.
Urich treat this monster column with length 3.5 m as 'slender' and apply the famous formula to it. But this core corner column, there are four!, is nothing but slender. It will not follow the idealistic formula. It would have been pretty simple to pick out this column from the rubble - 90 mm thick flanges!! - and see how they fractured ... due to bending? How apply an impact load on them? I am pretty certain that these columns were cut using some exotic controlled demolition device.
That the upper part C was destroyed prior to part A is affected is pretty obvious from all videos.
I cannot understand that the liers do not accept that, but try to explain or develop some strange crush down model with gravity. Luckily it is not possible. When two structures of similar types, parts C and A, collide, both are affected and the stronger elements will damage the weaker elements. As these core corner columns are the strongest elements in the structure, they should have remained undamaged!
On the other hand, the structures being destroyed by controlled demolition, these columns are the first to be cut.
PS - your web site is pretty awful!