Example $3\mathrm{.}8$ Two Rows of Bars

Determine the design moment strength of a rectangular concrete section reinforced with six no$.9$

bars in two rows $($Fig$.3\mathrm{.}22).$

Given: $b=12in.,d=23\mathrm{.}5in.,h=27in.,d_t=24\mathrm{.}5in.,f_c^{\text{'}}=4$ksi, and $f_y=60$ksi.

Figure $3\mathrm{.}22$ Example $3\mathrm{.}8.$