Question

As per IS 456 : 2000, Limit state of collapse – flexure, the maximum strain in reinforcing bars under tension at failure shall not be less than ……… , where \( f_y \) is the characteristic strength of steel and \( E_s \) is the Modulus of elasticity of steel.

• A. \( \frac{f_y}{E_s} \)
• B. \( 0.002 + \frac{f_y}{E_s} \)
• C. \( \frac{f_y}{1.15 E_s} \)
• D. \( 0.002 + \frac{f_y}{1.15 E_s} \)

Hint:

- Ensuring adequate tensile strain in reinforcing steel improves ductility and prevents brittle failure in flexural members.

Answer 1

The Correct Option is B

Step 1: Understanding maximum strain in reinforcing steel. - As per IS 456:2000, the maximum tensile strain at failure for reinforcing steel should be at least \( 0.002 + \frac{f_y}{E_s} \). - This formula accounts for the elastic strain (\( \frac{f_y}{E_s} \)) and an additional plastic strain (0.002), ensuring ductile failure. Step 2: Importance in design. - This strain ensures sufficient rotation capacity of the section before failure. - It prevents brittle failure, allowing warning signs before collapse. Thus, the correct answer is (B) \( 0.002 + \frac{f_y}{E_s} \).