State the effect of the induction of  the pre-stresses

The net effect of the induction of  the pre-stresses shall be to decrease the tensile stresses (produced due to the external loads on the beam element) at the bottom side of beam and to increase the compressive stresses (produced due to the external loads on the beam element) at the top side of  the beam. Though these pre-stresses shall have a positive effect in the form of
decrease of  tensile stresses (against which  the concrete is weak) at the bottom side, these may  lead to increase of compressive stresses to an extent that the concrete may, instead, fail in compression at the top side of beam.