They are easy to use but often unrealistic because they never cool down. :
The "long story" of fire design for steel structures within the Eurocode framework is a journey from simple, "one-size-fits-all" fire tests to sophisticated engineering that mimics real-world physics.
: Using Computer Fluid Dynamics (CFD) to "see" exactly how smoke and heat move.
: How the loads (furniture, people, snow) change when the building is burning.
Historically, fire design was —you just had to survive a standard furnace test (the ISO 834 curve) for 30, 60, or 90 minutes. Eurocode 1 revolutionized this by offering two paths: Nominal Fires (The Old Way) :