Minimum steel in RCC slabs — as a percentage of gross cross-sectional area, the minimum tensile reinforcement in slabs shall be:

Introduction / Context:
Minimum reinforcement limits in slabs prevent sudden cracking due to shrinkage, temperature, and early-age effects and ensure a minimum ductility/reserve capacity. IS 456 specifies different minima for bar types; many MCQs test the commonly adopted value for deformed bars used in modern practice.

Given Data / Assumptions:

• Reinforcement is high strength deformed (HYSD) bars (typical current practice).
• Percentage is with respect to the gross concrete area of the slab section.
• Single layer distribution in each direction, as per slab detailing norms.

Concept / Approach:

IS 456 prescribes not less than 0.12% for deformed bars (and 0.15% for mild steel). This limit controls crack widths and provides a base level of ductility under service actions. Therefore, the minimum tensile steel in slabs (for HYSD) is 0.12% of the gross area.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Cross-check with code tables or design handbooks summarizing IS 456 limits for slabs.

Why Other Options Are Wrong:

0.10% is below code minima; 0.15% corresponds to mild steel bars, not HYSD; higher options exceed the minimum and are not the standard requirement.

Common Pitfalls (misconceptions, mistakes):

Using beam minimums for slabs; ignoring the bar type distinction in the code.

Final Answer:

0.12%