# For a slab spanning in two directions, the ratio of span to the depth of slab should not exceed

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For a slab spanning in two directions, the ratio of span to the depth of slab should not exceed

1. 10
2. 20
3. 35
4. 50

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Correct Answer - Option 3 : 35

Concept:

Control of deflection:

The vertical deflection limit may generally be satisfied if

(a) Basic span to effective depth ratio for span up to m is

Types of Beams: $\frac{{{\rm{span}}}}{{{\rm{effective\;depth}}}}$

For cantilever → 7

For simply supported → 20

For continuous → 26

(b) For span > 10 m effective depth $= \frac{{{{\left( {{\rm{span}}} \right)}^2}}}{{10 \times {\rm{A}}}}$

Where ‘A’ is span to effective depth ratio for span up to 10 m.

(c) Deflection check for two way slab:

 Support Condition Span/overall depth Mild steel Fe415/Fe500 Simply supported 35 28 Continuous 40 32

So, From the above table It is clear that Span/depth ratio for two way slab should not be greater than 40. But From the given options, 35 is the closest one.