In the working stress method of R.C.C. design, the modular ratio between steel and concrete used is
- A230/3σcbc
- B230/σcbc
- C280/3σcbcCorrect
- D280/σcbc
Solution
Concept
Modular ratio in WSM
Formula
m = 280 / (3 σcbc)
Step-by-step solution
1. IS 456 Annex B: m = 280 / (3 σcbc), σcbc in N/mm². 2. For M20, σcbc = 7: m = 13.33.
Explanation
The modular ratio is the ratio of the moduli of steel and concrete, adjusted for creep.
Why the other options are wrong
230 is not used in IS 456.
Shortcut
m = 280/3σcbc.
Common mistake
Dropping the 3.
Correct answer: C) 280/3σcbc