The short-term static modulus of elasticity Ec for structural concrete defining the slope of the tangent to the stress-strain diagram may be estimated from (where fck is the characteristic compressive strength of concrete.)
- A2000√fck MPa
- B3000√fck MPa
- C4000√fck MPa
- D5000√fck MPaCorrect
Solution
Concept
Modulus of elasticity (IS 456 cl. 6.2.3.1)
Formula
Ec = 5000 √fck (MPa)
Step-by-step solution
1. IS 456:2000 gives Ec = 5000 √fck N/mm².
Explanation
The short-term static modulus of concrete is estimated as 5000√fck. For M25 it is about 25 000 MPa.
Why the other options are wrong
2000, 3000 and 4000 are not the multipliers in IS 456.
Shortcut
Ec = 5000√fck.
Common mistake
Using 4700√fck (the ACI value).
Correct answer: D) 5000√fck MPa