The 'modular ratio' m used in working stress method (WSM) for RCC is defined as:
Choose the correct answer
m = fck / fy (concrete to steel grade ratio)
m = Es/Ec = 280/(3σcbc) — converts steel area to equivalent concrete; used in IS 3370 WSM for liquid-retaining structures
m = 1.5 for all concrete grades
m = fy / fck
Correct Answer
B. m = Es/Ec = 280/(3σcbc) — converts steel area to equivalent concrete; used in IS 3370 WSM for liquid-retaining structures
Why is this the answer?
Modular ratio m = Es / Ec = 280 / (3σcbc) per IS 456 (older WSM). σcbc = permissible compressive stress in concrete bending (MPa). Typical: M20 concrete: σcbc = 7 MPa → m = 280/21 ≈ 13.3. Used in: transformed section (steel area converted to equivalent concrete = m × Ast). WSM replaced by LSM in IS 456:2000, but WSM retained for water-retaining structures (IS 3370 Part 2). Transformed NA: bx²/2 = m × Ast × (d−x).
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