In an R.C.C. beam (25 cm width, 70 cm effective depth), concrete and steel stresses are 62.5 kg/cm2 and 250 kg/cm2 respectively. With m = 15, calculate the neutral axis depth_______________?
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Answer: C. 30 cm
Explanation
Elastic theory formulas incorporating a modular ratio of 15 yield a neutral axis depth of 30 cm. Equating the moment of the compression area to the tension area determines the exact neutral axis location. Given stress values for concrete and steel establish the triangular stress distribution across the beam section. The neutral axis is the imaginary line within a beam where bending stresses are equal to zero. Working stress design assumes that materials remain elastic under normal service load conditions. Effective depth measures the distance from the extreme compression fiber to the centroid of tensile steel.
Engineers calculate neutral axis depths to determine the resisting moment capacity of reinforced concrete beams. Accurate stress analysis prevents overstressing of concrete compression zones in structural members. Standard rectangular beam formulas are fundamental tools taught in structural engineering academic courses. Option A suggests 20 cm, which underestimates the neutral axis depth for the given stress parameters. Option B proposes 25 cm, resulting from an incorrect ratio of concrete and steel stress values. Option D specifies 35 cm, which overestimates the neutral axis position within the 70 cm effective depth.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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