What they were trying to do was create a computer model that replicated as closely as possible what one saw the builing doing; that is, collapsing so rapidly into it's own footprint at times at freefall speed as if the steel columns supporting the structure suddenly weren't there anymore and had been removed somehow.
This raises an awful lot of questions; awkward ones, like what about all the other buildings, thousands of them all over the world that are built the same way, are they all as fragile and vulnerable to demolishion by fire as WC7?
Years ago I met, socially, a very prominent archetect and structural engineer indeed and he told me in no uncertain terms that the 'conspiracies theories' about 9/11 were all nonsense and it simply wasn't true that it was a unique occurance. There were other cases of steel-frame, high-rise buildings collapsing due to office fires.
I asked him, politely, if he could tell me where this had happened and in which coutries as I'd like to see them to 'settle my mind.' He looked somewhat surprised that I'd even bothered to ask him about this, as 'everybody knows this in the profession.' 'I can't tell you off the top of my head, but give me your e-mail and I'll send you the data, tomorrow.'
Nothing came the next day, or a week later. So I gave him a nudge and he said he'd been very busy on some mega-project in Saudi Arabia. I never heard from him again, and, as far as I know there are no other examples of a similar steel-frame building collapsing, totally demolishing, after a fire anywhere in the world.