A rectangular reinforced concrete beam is to be designed to withstand a moment, $M_u=450ft.-k,$ the maximum moment on a simple span beam. This moment includes the self$-$weight of the beam. Architectural restraints entail that the beam width, b$,$ is $15$ in $.$ and the total height, $h,$ is $24$ in $.$ Assume $d=20in.$ and $d^{\text{'}}=2\mathrm{.}5in.,$ if necessary. Design the flexural reinforcement, using #$8$ bars for bottom $($tension$)$ reinforcement and #$8$ bars for top $($compression$)$ reinforcement, if necessary. Regardless of whether the beam is a doubly reinforced beam or not, assume the tensile reinforcement is placed in two equal rows of #$8$ bars $($i$.$e$.,$ an equal amount of reinforcement in each row$)$ spaced with a $1\mathrm{.}0-in.$ clear distance between rows. Assume $f_c^{\text{'}}=4,000$ psi and $f_y=60,000$ psi. Start by verifying whether the section can be designed as a singly reinforced section. $(40$ pts$.)$