For Problems $8\mathrm{.}11$ to $8\mathrm{.}19,$ for the beams and loads given, select stirrup spacings if fc$=4000$ psi normal$-$weight concrete and f $=60,000$ psi. The dead loads shown include beam weights. Do not consider movement of live loads unless specifically requested. Assume #$3$ stirrups unless given otherwise.

$8\mathrm{.}15$