The doubly reinforced section is normally required under the following circumstances:

1. Sectional dimensions are restricted due to requirements of head room, appearance etc. and the strength of given singly reinforced section is inadequate.
2. The beam which acts as a flanged beam at midspan becomes a rectangular beam at supports of a continuous beam. At support tension occurs on top making the flange ineffective, and therefore, the section becomes inadequate to resist large peak value of support moment.
3. Basement with lower plinth level and combined with ventilator compels one to design a doubly reinforced plinth beams.
4. Compression steel is provided sometimes to reduce the deflection i.e. to increase the stiffness and also to increase the rotation capacity.