Determine $M_n$ for the partially prestressed beam section shown below. Use $f^{\text{'}}{?}^c=5000,$ strand $f_{pu}=270$ksi and $f_{pe}=0\mathrm{.}55f_{pu},$ and $f_{py}=0\mathrm{.}85f_{pu},$ and nonprestressed bars $f_y=60$ksi. The area of prestressing steel is $A_{ps}=0\mathrm{.}918i{n}^2$ from $6-\frac{1}{2}"$ diameter $7-$wire strands, and the area of nonprestressed reinforcement $A_s=1\mathrm{.}2i{n}^2$ from $2$ No$.7$ reinforcing bars. The effective depth of the prestressing steel $d_p$ and mild steel $d_s$ and width $b$ are shown in the figure below. Assume that the prestressing steel is fully bonded. Is the flexural capacity adequate if the factored load moment $M_u=310ft-$kips? $(50)$

$A_{ps}=0\mathrm{.}918i{n}^2,f_{pe}=148\mathrm{.}5$ksi

$d_p=20\mathrm{.}75in{f}_{pu}=270$ksi

$A_s=1\mathrm{.}2i{n}^2,f_{py}=229\mathrm{.}5$ksi

$d_s=21\mathrm{.}5in,f_y=60$ksi

$,f_c^{\text{'}}=5$ksi

$d_t=22in(ACl),$

Strands layout: $2$ strands at $2$ in$,2$ strands at $4$ in$,$ and $2$ strands draped at $4\mathrm{.}375$ in from bottom fiber