Question

Assertion (A): The behaviour of an over reinforced beam is more ductile than that of under reinforced beam.
Reason (R): Over-reinforced beam contains more steel and steel is more ductile than concrete.

• A. both A and R are true and R is the correct explanation of A
• B. both A and R are true but R is not a correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is D A is false but R is true

(d)
In under reinforced beam, rate of gain of stress in steel is more than rate of concrete. So steel reaches its maximum permissible value earlier than concrete and fails first hence it is ductile in failure. In case of over- reinforced section stress in concrete reaches its maximum permissible value first so concrete fails first and it is brittle failure since concrete is brittle.