Q1: The following two statements are made with reference to a simply supported under-reinforced RCC beam :

1. Failure takes place by crushing of concrete before the steel has yieled.
2. The neutral axis moves up as the load is increased.

With reference to the above statements, which of the following applies ?

ANS:C - Both the statements are true.

@Sumit Dhyani.

you are partly correct but the answer is still D because;

"Failure takes place by crushing of concrete before the steel has yielded" Although the first part of statement 1 is correct but 2nd part isn't because steel has already yielded far before the ultimate failure due to crushing of concrete.

Regarding Statement 2 it's correct because when steel yields, the bottom part of the beam starts cracking and that area becomes negligible, hence N/A keeps shifting upwards as the cracks propagate higher and higher.

Thus option D is correct.