Now, I have assumed a slab depth, a reversed parabolic profile, and calculated the prestressing force required to balance the dead load.

I obtain the number of tendons in each span, ASSUMING A 20% LOSS OF PRESTRESS AT SERVICE.This is followed by computing the stresses at service,computing mild steel (if tensile stresses exceed permisable limits), computing ultimate moment capacities,comparing factored and ultimate moment capacities,provision of mild steel if required for ultimate state,checking for shear and COMPUTATION OF PRESTRESS LOSSES.

Now, my question is if prestress losses exceed 20% say 30% at service, then all calculations have to be repeated , right?In the second cycle now, we again calculate the losses and compare if they are within 30%, right?

So we continue this process until we get reasonable convergence between losses calculated and the losses intially taken,right?

Is this the procedure followed in the commercial software too?

What should be a reasonable convergence?(i.e. the difference between losses compted and losses used in calculations??)