The Art of Reading Buildings Practice Test

In a fire, steel loses strength as temperature rises, becoming softer and more deformable. When exposed to high heat, its yield and ultimate strengths drop and its stiffness decreases, so a member under load can bend, sag, or elongate before it fails. That makes the tendency to soften and elongate when heated the key weakness from a fire service perspective. It doesn’t harden with heat, and it doesn’t resist deformation at high temperatures; in fact, it expands and deforms more readily under fire conditions.