Question

For a simply supported beam of span 12 m, the basic value of span to effective depth ratio is

1. 20
2. 26
3. 65/3
4. 50/3

Answer 1

Correct Answer - Option 4 : 50/3

Concept:

As per IS 456 Cl 23.2.1, deflection can be limited, by controlling the span to effective depth ratio as given in the following table.

Type of Beam	Span to effective depth ratio (basic) for span < 10m	If span > 10
Cantilever	7	These values should be multiplied by 10/span
Simply supported	20
Continuous	26

Calculation:

Given, Span = 12 m (> 10 m)

So, Span to effective depth ratio for a simply supported beam

\(\rm \dfrac{Span}{Effective \ depth}\) = 20 × \(\rm \dfrac{10}{span}\) = \(\dfrac{20\ \times\ 10}{12}\) = \(\dfrac{50}{3}\).

Hence, Span to effective depth ratio for a simply supported beam will be 50/3.