Difficulty: Easy
Correct Answer: equivalent section
Explanation:
Introduction / Context:
When analyzing composite concrete–steel sections under bending, we often 'transform' the steel into an equivalent area of concrete using the modular ratio m = Es/Ec. This permits the use of simple elastic beam theory on a homogeneous 'equivalent' section, enabling the calculation of neutral axis, stresses, and curvature without explicitly dealing with two materials in parallel.
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Concept / Approach:
By multiplying the steel area by m, we obtain an area that, under the same strain, carries the same force as the original steel. Adding this to the concrete area gives the 'equivalent section' used for elastic analysis. The term 'cracked section' refers to tension-side concrete being ignored after cracking, which is not the same definition as requested here.
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