I have even heard the argumet:
If you think DYNAMIC loads are not important take the challenge of even a 10kg weight dropped from 12ft (WTC story height)and try and catch it. WE WILL SEND THE FLOWERS.
I say: How about dropping 10kg weight 12ft and having 70 people stacked vertically (like the 70 floors of undamaged building were) try to catch that weight?
I'm pretty confident that the weight would be caught way above the ground.
The argument as stated is that if you drop something from a height of 12 feet, it will be moving at about 19 miles per hour by the time it reaches the ground. It doesn't matter whether it is a single brick or a 30 story building. After falling 12 feet it will be moving at about 19 mph.
So if the lower 79 floors are strong enough to support a stationary 31 story building, do you think they will be strong enough to support a 31 story building falling at 19 mph?
That's what I'm looking into. I honestly believe there are factors that the naysayers are not considering.
(1) The 'pancake theory' is ridiculous. The WTC did not pancake. They were completely pulverized into an indiscriminate pile of smoldering rubble.
(2) The structural make up of the towers is seen is completely inconsequential to it's collapse. This approach is wrong for two major reasons:
(a) The floors 31 floors falling onto the remaining 79 floors are likewise constructed, and use the same materials. To say they were able to completely smash threw the reaming building unimpeded is crazy.
(b) The lower 79 floors are made out of stronger, thicker, heavier, and more closely spaced beams. Simply put. more mass is always in the lower 2/3rds of a building to keep it stable, and give it the strength to hold the load of the higher floors.
(3) The WTC was not 'conventionally' built like below.
The WTC flooring was a very heavy duty set of cross braced Vierendeel trusses.
The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns. The perimeter structure containing 59 columns per side was constructed with extensive use of prefabricated modular pieces each consisting of three columns, three stories tall, connected by spandrel plates.[31] The spandrel plates were welded to the columns to create the modular pieces off-site at the fabrication shop.[32] Adjacent modules were bolted together with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, transmitting shear stress between columns, allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically so the column splices between adjacent modules were not at the same floor.
One of the reasons It is important to point this out is that the collum, perimiter wall, and the floor trussing was made to work in concert in carrying the entier load, and stresses of the building. In a starnderd building the colum and outer skin would carry th weight of the flooring, but in the WTC the flooring was part of the structures rigidity, and had it's part in sharing laterail, horizotial, and twisting loads. Meaing this, the flooring was not just suspended weight. It was part of the load bearing structer. Energy that affected any one point of the building would be absourbed by all thre systems at the same time.
(4) No consideration is given to how much energy (force) is dissapated in the destruction of an object. I have heard staments that oveR 4.1 billion joules OR 3,319,073,609 pound-force/foot² = 23,049,122 psi of energy would have built up from the falling structer before it hit the building underneith it. That means it would only take an affected are of 434.89 Sq inches in the 53,000 psi rated center colum to absorb that impact.
