engineering recuitment BHEL Engineer Trainee Mock Test 2025 Reinforced Concrete Structures Beams and Slabs
In a doubly reinforced rectangular beam, bending stress induced in compression (i.e. concrete) and tension (i.e. steel) are σch and σst, respectively. The depth of neutral axis is kd (where d is effective depth) from top compression face and modular ratio is m. Which one of the following represents correct combination in under reinforced beam?
1
\(\frac{{{{\rm{\sigma }}_{{\rm{cb}}}}}}{{{{\rm{\sigma }}_{{\rm{st}}}}}} = \frac{{{\rm{mk}}}}{{1 - {\rm{k}}}}\)
2
\(\frac{{{{\rm{\sigma }}_{{\rm{cb}}}}}}{{{{\rm{\sigma }}_{{\rm{st}}}}}} = \frac{{\rm{k}}}{{{\rm{m}}\left( {1 - {\rm{k}}} \right)}}\)
3
\(\frac{{{{\rm{\sigma }}_{{\rm{cb}}}}}}{{{{\rm{\sigma }}_{{\rm{st}}}}}} = \frac{{{\rm{mk}}}}{{1 + {\rm{k}}}}\)
4
\(\frac{{{{\rm{\sigma }}_{{\rm{cb}}}}}}{{{{\rm{\sigma }}_{{\rm{st}}}}}} = \frac{{\rm{k}}}{{{\rm{m}}\left( {1 + {\rm{k}}} \right)}}\)