$4-39.$ If column $AB$ is made from high strength pre$-$cast

concrete and reinforced with four $20$ mm diameter A$-36$

steel rods, determine the average normal stress developed

in the concrete and in each rod. Set $P=350kN.$

$*4-40.$ If column $AB$ is made from high strength pre$-$cast

concrete and reinforced with four $20$ mm diameter A$-36$

steel rods, determine the maximum allowable floor

loadings P$.$ The allowable normal stress for the high

strength concrete and the steel are $({}_{\text{a}\text{l}\text{l}\text{o}\text{w}}{)}_{\text{c}\text{o}\text{n}}=18$MPa

and $({}_{\text{a}\text{l}\text{l}\text{o}\text{w}}{)}_{st}=170$MPa, respectively.

Probs. $4-39/40$