According to ACI$318-02,$ find the value of $$ that should be used in computing the design moment strength $)$ for the beam section shown.

$f_c^{\text{'}}=4$ksi

$f_y=60$ksi

$A_s=5\mathrm{.}08i{n}^2$

$4-$No$.10$ bars $($tension$)$

$$

$0$

$0$

ubrace$(ubrace{)}_{21\mathrm{.}5}$

$12"$