Which of the following statements is /are true?
1
Doubly reinforced beams are recommended when depth of beam is not restricted.
2
Doubly reinforced beams are recommended when breadth and depth of beam is restricted
3
The maximum strain in concrete at the level of compression reinforcement is 0.0035× (1 - d'/xm), Where d' is centre of compression reinforcement and xm is depth of neutral axis.
4
The maximum strain in concrete at the level of compression reinforcement is 0.0035× (1 - d'/d), Where d' is centre of compression reinforcement and d is effective depth of beam..