For Problems $8\mathrm{.}11$ to $8\mathrm{.}19,$ for the beams and loads given, select stimup spacings if f$\_($c$)^(\text{'})=4000$ psi normal$-$weight concrete and

f$\_($y$)=60,000$ psi. The dead loads shown include beam weights. Do not consider movement of live loads unless specifically requested.

Assume $3$U stirrups unless given otherwise.

Problem $8\mathrm{.}15($One ans. $1$ @ $6$ in$.,8$ @ $12$ in$.)$