The cross$-$section is for a beam that is not exposed to weather nor in contact with the ground. The

overall depth is $600mm,$ width is $250mm,$ steel yield strength of reinforcing steel is $420$MPa,

compressive of concrete is $42$MPa, the beam is reinforced with $2$ layers of tension steel, each layer

consists of $3$ No$.25$ bars. The vertical spacing between the two layers of reinforcing steel is the

minimum permitted by ACI$318$ code. Assume the stirrups are No$.10$ stirrups. Calculate the

flexural design capacity, $\frac{O}{M_n}.$ Support your calculations with fully labeled strain and force

diagrams.

$2$MPa