Problem $3$ A $25-$ft long simply supported rectangular reinforced concrete beam is to be designed to

carry its self$-$weight, super$-$imposed $($additional$)$ unfactored dead load of $500l\frac{b}{f}t,$ and unfactored live

load of $1150l\frac{b}{f}t.$ The beam depth must meet ACI minimum thickness for bypassing deflection

calculations. The beam width should be approximately one$-$half of the depth but not less than $12in.$ The

designer has decided to use No$.8$ longitudinal bars and No$.4$ stirrups to avoid having too many bar sizes

for the project. Moreover, the designer has selected A$615$ Gr$.60$ reinforcement and $6,500$ psi concrete.

Design an efficient beam such that $\frac{M_n}{M_u}$ does not exceed $1\mathrm{.}15.$ Show the cross section of your design;

the sketch must show the member width, depth, number and size of bars, and stirrup size with the clear

cover you used in your design.