$8\mathrm{.}3.$ Using the expressions suggested in Section $8\mathrm{.}4\mathrm{.}2,$ determine the design moments for a three$-$span beam that is continuous over four supports. $($The ends are integral with the column supports.$)$ Determine the critical design positive and negative moments for each span. Assume that the structure carries a uniformly distributed load of $300l\frac{b}{f}t$ and that each span is $30ft.$