Problem $4$

A concrete beam with a rectangular section that has a width of $b$ and effective depth of $535mm.$ Use a design moment Mu of $200kN-m,f_c^{\text{'}}=40$MPa and $f_y=420$ MPa.

Take $b=250mm,$ Find the required flexural steel reinforcement.

Take steel ratio $=0\mathrm{.}015,$ Find the required beam width $b.$