The 'minimum reinforcement' in RC beams (IS 456) ensures:
Choose the correct answer
Maximum strength is achieved
Ductile behaviour after cracking — minimum steel carries tensile force from concrete at cracking, preventing brittle sudden failure
No deflection under service loads
Compressive strength governs design
Correct Answer
B. Ductile behaviour after cracking — minimum steel carries tensile force from concrete at cracking, preventing brittle sudden failure
Why is this the answer?
IS 456 Cl. 26.5.1.1: Minimum Ast = 0.85/fy × bw × d (in mm²) where fy in MPa. Purpose: prevent sudden (brittle) fracture if concrete cracks — minimum steel takes over tensile force. If Ast = 0, a cracked beam fails suddenly (no ductility). Minimum ensures: Ast_steel can carry at least the tensile force present in concrete just before cracking (M_cr = 0.7√fck × Z). Avoids over-reinforced sections too (Ast_max = 0.04 bD).
Related RCC MCQs
More solved RCC questions for AE/JE Civil Engineering exams.
- The 'ductility' of RC structures is improved under earthquake loading by:
- For a circular RC water tank with rigid base, the hoop tension is maximum at:
- The 'end block' in a post-tensioned member is specially designed for:
- A 'shear wall' in a multi-storey RC building acts as:
- The 'minimum clear cover' for reinforcement in a RCC beam in severe exposure (IS 456) is:
- The 'torsion' in RC beams is resisted by:
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