D$3/$P$2.$

A typical cross$-$section of a reinforced concrete

beam is shown in the figure below. Use an effective

depth of $600mm.$

a$)$ Determine the required number of $35M$ rebars

corresponding to the balanced condition.

b$)$ Find the corresponding factored moment

resistance.

Given:

$f_c^{\text{'}}=25$MPa

$f_y=400$MPa

${}_c=0\mathrm{.}65$

${}_s=0\mathrm{.}85$

$E_s=200000$MPa