Stephen A. Lawrence wrote:
On a smaller scale than skyscrapers, where one finds both wood frame and steel frame buildings of roughly similar size and shape, in a good hot fire, and all else being equal, a wood-frame building will typically stand _longer_ than a steel-frame building before collapsing.
This was discovered in the 1960s and 70s at the National Bureau of Standards. They sent experts to look at burned warehouses and other buildings, and they constructed a huge laboratory to burn houses and other structures indoors at their Gaithersburg, MD campus. My father worked there at the time and I went out to see it.
Based on this research, construction standards were revised and steel is now enclosed in concrete. However, I believe that even now some wooden structures have survived fire better than steel does.
When the twin towers were struck by airplanes, leading experts knew right away they would soon collapse the way they did -- straight down. One of these experts try to contact officials in New York to warn them to evacuate the building, but he could not get through. He said the only surprise was that the buildings held up as long as they did.
- Jed
