Moment Capacity According to the AASHTO Method

The ultimate capacity (Mu-prvd) is calculated according to one of the following four cases:

If the neutral axis is within the deck (c<h_t) and the prestressed steel reaches the yielding point (reinforcement index, ri < 0.36 β₁), then LFD Eq. 9-13 is used.
If c > h_t and ri < 0.3β₁, use LFD Eq. 9-14.
If c < h_t and ri > 0.3β₁, use LFD Eq. 9-22.
If c > h_t and ri > 0.3β₁, use LFD Eq. 9-23.

The effects of any partially developed strands are accounted for by linearly reducing the nominal area of the strands at a given section within the development length. (For more information, see Transfer and Development Length) This is shown as the effective area of steel (A*s) on the printout.