The coefficient of linear thermal expansion of steel is around 1/100,000 per °C.
This means that at a temperature of 420°C, a 5m steel beam will:
1. Attain 800MPa elastic stress under restrained expansion
2. Expand 2cm under unrestrained expansion.
The Twin Towers beams were made of steel with a yield stress of 248MPa or 345MPa. This means that in case of #1, the beams would have buckled. This buckling could lead to beam collapse. What effect would that have?
1. It could pull in the exterior walls
2. It could cause core column buckling
The core columns in the impact zones were mainly 36cm and 30cm wide flange sections of 248 or 290MPa ... Read even more
