For the beam shown below, calculate $a,c,{}_t,$ and $M_n$ by varying the amount of

tension reinforcement and plot a graph of $A_s$ vs $M_n.$ You may create an Excel

spreadsheet to perform the calculation. Given: $f_y=60,000$psi and $f^{\text{'}}c=4,000$psi

Note: Vary $A_s$ from $1\mathrm{.}0i{n}^2$ to $5i{n}^2$ at $0\mathrm{.}5i{n}^2$ increment.