Effect of prestress in an reinforced cantilever beam

The effect of prestress in an ordinary reinforced cantilever beam and a prestressed concrete (PSC) beam. When no load is present on both the beams, the top surface of the PSC beam is having a curvature towards the top due to the prestressing force. In this stage of no-load, the performance of an RC beam is equally good. But as loads come on both the beams, the originally flat top surface of the RC beam shall be put to a downward curvature and the top surface of it may be liable to cracking. The PSC beam behaves well even in the loaded condition as the top section is still not subjected to a large amount of tensile stresses (as the compressive prestresses neutralize some or most or all the tensile stresses produced due to external loads, applied later on).