Have a look at an actual explosive being fitted to a column in...

Have a look at an actual explosive being fitted to a column in the pic below. Look at the 45 degree angle. That's why that column pic I posted above is so suspect. Level of molten metal on both sides is unusual as I mentioned earlier, that is not the norm.

Also if you wanted to segment a column wouldn't you just use an excavator to push it from one side with cables under tension directing its fall thereafter. I mean the rivets/bolts would snap right. I am no construction expert, someone else may know better. I don't think you would go to the trouble of oxy/arc cutting to segment the column? That seems pretty dangerous to me? I wouldn't feel that comfortable doing the cutting knowing tonnes are about to fall down around me. I would be interested to hear from a construction expert.