Question

The span to overall depth ratio of a simply supported two-way slab with mild steel reinforcement is

• A. \( 40 \)
• B. \( 25 \)
• C. \( 35 \)
• D. \( 20 \)

Hint:

For structural design problems, refer to the relevant code (e.g., IS 456:2000 for India). The span-to-depth ratio varies based on support conditions, slab type (one-way or two-way), and steel grade. For mild steel, use the basic values unless modification factors are specified.

Answer 1

The Correct Option is C

Step 1: Understand the span-to-depth ratio for a two-way slab.
The span-to-overall-depth ratio (\( \text{span}/D \)) for a simply supported two-way slab with mild steel reinforcement is governed by IS 456:2000 (Clause 23.2.1). A two-way slab has a longer-to-shorter span ratio \( \leq 2 \), and the ratio ensures deflection control.
Step 2: Apply the standard from IS 456:2000.
As per IS 456:2000, Table 4, the basic span-to-overall-depth ratio for a simply supported two-way slab with mild steel reinforcement (Fe 250) is: \[ \text{span}/D = 35. \] This value may be modified based on reinforcement percentage or steel stress, but no such details are provided, so the basic value applies.
Step 3: Compare with the options.
The standard value of 35 matches option (3), confirming it as the correct choice for a simply supported two-way slab with mild steel reinforcement.