ANS:C - 10 cm to 12 cm

1. Spacing Requirements: The breadth of a ribbed slab, which refers to the width between two adjacent ribs, should be sufficient to accommodate the reinforcement bars and ensure proper spacing between them. In the case of a ribbed slab containing two bars, a range of 8 cm to 10 cm for the breadth allows for adequate spacing between the bars while ensuring efficient utilization of space within the slab.
2. Structural Considerations: The chosen breadth range of 8 cm to 10 cm strikes a balance between structural requirements and practical considerations. It provides enough room for placing and securing the reinforcement bars without overcrowding the ribbed slab, which could lead to difficulties in concrete placement, compaction, and consolidation.
3. Construction Efficiency: A narrower breadth within the specified range (8 cm to 10 cm) facilitates easier handling of reinforcement during construction, minimizing the risk of congestion and ensuring proper embedment of bars within the concrete matrix. This promotes construction efficiency and helps achieve the desired structural performance of the ribbed slab.
4. Design Flexibility: While specific project requirements and design considerations may vary, the breadth range of 8 cm to 10 cm offers a practical and commonly acceptable solution for ribbed slabs containing two bars. It provides designers and engineers with flexibility in accommodating varying structural loads, span lengths, and other design parameters while maintaining structural integrity and constructability.