Cast iron columns are unpredictable and fail, on average, in about how many minutes?

The average failure time for cast iron columns in fire conditions is approximately 30 minutes. Cast iron is relatively brittle and, while it has good compressive strength, it does not perform well when subjected to high temperatures. When exposed to fire, cast iron can lose its structural integrity much faster than steel, which can deform under heat but tends to remain stable longer.

The 30-minute timeframe is significant because it highlights the critical aspect of fire response planning and the need for firefighters to be aware of the vulnerabilities of buildings constructed with cast iron elements. This information serves as a guide for risk assessment during firefighting operations, ensuring that personnel can make informed decisions about fire behavior and structural stability in a building that contains cast iron columns. It's vital for keeping firefighters safe and effectively managing fire incidents.