Problem $2$

Find $M_n$ of the sections shown below for the given two different material properties $($total four $M_n$ calculations$).$

a$)$ use $f_c^{\text{'}}=3000$ psi and $f_y=60,000$

b$)$ use $f_c^{\text{'}}=5500$ psi and $f_y=60,000$ psi