There are 3 types of RCC beam section
- Over Reinforced Section
- Under Reinforced Section
- Balanced Section
If the Section has more steel than required it will lead to brittle failure(concrete will fail first) of section that is the case of over reinforced section and it is not recommended in design of beams.
If the section has less steel (not less than minimum requirement) than required it will be more desirable as there will be ductile failure (steel will fail first) of section and warning time is there before failure.
Therefore balanced and Under Reinforced section are desirable for the safety of section instead of over reinforced section.
More percentage of steel used more will be Moment of resistance. Refer IS 456 (2000)