Problem $2$

For the given singly reinforced rectangular section shown in Figure $2$ with $f_c^{\text{'}}=30$MPa,$f_y=400$MPa, calculate the moment resistance $).$

Problem $3$

a$)$ For the given doubly reinforced rectangular section shown in Figure $3$ with $f_c^{\text{'}}=30$MPa,$f_y=400MP,$ calculate the moment resistance $(M{r}_r)$; b$)$ how much extra $M_r\%$ is gained compared to problem $2.$