The cross$-$section shown below is used for a pedestrian bridge on campus. Each stem of the beam cross section is reinforced with $4-$No$.8$ bars as indicated in the figure. The bridge will have to support a pedestrian load $($live$-$load$)$ of $90l\frac{b}{f}{t}^2$ over the bridge top surface. In addition to self$-$weight, the bridge will have to support $40l\frac{b}{f}{t}^2$ of superimposed dead load. What is the maximum simply supported span for which the beam section can be used to comply with ACI $318-19$ provisions? $(30$ pts$)[$Hint: convert the surface loads given in $l\frac{b}{f}{t}^2$ to line loads in kip$/$ft to be able to solve the problem$]$

Note: the beam span is perpendicular to the page.

$f^{\text{'}}=4,000$

$f_y=60,000$