Question

In limit state design method, the limiting values of the depth of neutral axis for Fe 415 steel is given by which of the following equations?

1. 0.53 d
2. 0.48 d
3. 0.46 d
4. 0.36 d

Answer 1

Correct Answer - Option 2 : 0.48 d

Explanation

Concept:

The ratio of limiting depth of neutral axis to the effective depth of the beam is given by

\(\frac{{{x_u}}}{d} = \frac{{{\rm{Max\;strain\;concrete}}}}{{\frac{{{\rm{Grade\;of\;steel}}}}{{{\rm{Modulus\;of\;Elasticity\;of\;steel}} × {\rm{F}}.{\rm{O}}.{\rm{S}}}} + 0.002 + {\rm{Max\;strain\;concrete}}}}\)

Note:

We know the standard values of the ratio of limiting depth of neutral axis to the effective depth (k) of the beam for different steel sections as following:

 x_u = k × d

Grade of Steel	Fe 500	Fe 415	Fe 250
‘k’ value	0.46	0.48	0.53

 

∴ For Fe415 grade limiting value of depth of neutral axis is 0.48×d