Concrete can be easily fractured by a small amount of properly placed high explosives and it will fall freely.
What do you see? All concrete.
Never on 9-11 do you see steel core columns in the core area. Those using official information without question have no explanation for anything.
The entire structure was made of concrete and steel. So to take a picture like that and try to make any claim regarding core steel or the lack of it is futile.
Also I believe you are working under some assumptions made a few of the more zealous groups out there. Groups who have no greater idea in mind than to sell their theory on it.
1. The "cores" are spoken of as large steel beams. The fact is, the actual core beams were made up of several connected beams, then filled and wrapped in concrete. As seen in this picture from the construction...
Carefully looking at the center, you can see it is solid and not hollow. That is because, as they built a certain number of floors up, they would then pour the concrete up to that point. This was the process, and and at the time a pretty radical departure from the classic skyscraper construction. Remember the twin towers were a new concept and not all of its constructions methods would become the modern standard or even be used beyond the towers.
You can plainly see in the picture that the "giant" steel cores, are in reality a lattice work of steel girders and supports thatched together to form a caged chamber that was then filled with concrete.
The problems with some of the theories out there are the way they are scrapped together from bits of knowledge from all over. They take of a fact and then they make assumptions to fill in the blanks. Then they may make sweeping statements or claims based on that patchy knowledge.
They ask "where are the giant steel core?". When in reality there weren't "giant steel cores" but rather a lattice work of steel supports filled with concrete. And thats why you don't see giant steel beams so many feet across or high at ground zero. The actual steel was big, but it wasn't an unheard of size for the time and type of structure. The cores they helped form however, were another matter. But those being a lattice work they came apart at their seams just like anything else would in such situation.
And then you have your extreme cases who take those errors already discussed and try to add to it, or make their theory unique and stand out. They will ask questions about the same already assumed steel cores and then add things like claims of concrete construction instead steel. They are technically right, but then so are the giant steel core theorists as well. The real truth is something in the middle, but the either way there is no giant steel core and the cores were not actually concrete either.
Then we have the real problem... People who for some reason have to take the embellishments and logical fallacies of the first two we mentioned, and add extreme conjecture to it all. Like claims the concrete cores were packed with explosives during construction, or the concrete itself was not really concrete but some kind of explosive material. Or the fantastical one about thermite added to the joints and support connections during construction.... This kind of thing helps no one and does an immeasurable amount of harm to everyone. I wish these people would stop and realize their ill-conceived and fantastical theories and flights of science -fiction casts an air of doubt on all who wish to understand this better. And keeps support at bay from many who may have otherwise been shown the real problems.