'Fire protection' for structural steel (IS 800 Cl. 16) is needed because:
Choose the correct answer
Steel corrodes rapidly in fire
Steel strength drops to 60% at 500°C — fire protection maintains structural integrity until evacuation; required FRR by IS 800 Cl. 16
Steel expands too much without protection
Fire protection only improves aesthetics
Correct Answer
B. Steel strength drops to 60% at 500°C — fire protection maintains structural integrity until evacuation; required FRR by IS 800 Cl. 16
Why is this the answer?
Steel at elevated temperatures: yield strength fy drops to 60% at 500°C and 23% at 700°C (IS 800 Table 21). Structural failure when steel temperature reaches critical temperature (typically 550°C for members at design load ratio). Protection methods: (1) Intumescent coating (expands and chars at heat → insulating layer); (2) Board/spray fire protection (gypsum boards, vermiculite spray); (3) Concrete encasement; (4) Water-filling hollow sections. Fire resistance rating (FRR) depends on protection thickness and material.
Related Steel Structures MCQs
More solved Steel Structures questions for AE/JE Civil Engineering exams.
- The 'residual stresses' in hot-rolled steel sections arise from:
- The 'effective slenderness ratio' for a single angle compression member (IS 800)...
- 'Fatigue failure' in steel structures occurs under:
- The 'tension field action' in a plate girder web after buckling means:
- Bolts in 'slip-critical' (HSFG) connections resist load by:
- The 'portal frame analysis' approximation for multi-storey frames under horizontal load...
Practice more Civil Engineering questions
This MCQ belongs to JE Level Premium Test Series. Full tests include timed attempts, rank comparison and subject-wise analysis.