[DoughtyOne]

One of the problems with these buildings are the vents, shafts and conduits that go up a number of floors. In the LA FIB fire the, the flames jumped a number of floors by this method. Luckily the fire became oxygen starved on the upper level and put itself out.

[finnman69]

One of the problems with these buildings are the vents, shafts and conduits that go up a number of floors.

Thats why building codes specify that vertical shafts be fire rated and pipe penetrations, gaps between curtainwalls and slabs, etc. be sealed with fire stopping to prevent flue effects and fire jumping floor to floor.

The WTC's biggest problem was you had an instantaneous acre sized fire on several floors with multiple penetrations into the building, destroying the compatmentation that was designed to halt the spread of a normal fire. You also had aviation kerosene as an accelerant pouring into the building.