Example $4\mathrm{.}4$

A square foundation $(BB)$ has to be constructed as shown in Figure $4\mathrm{.}10.$ Assume that $=105l\frac{b}{f}{t}^3,{}_{\text{s}\text{a}\text{t}}=118l\frac{b}{f}{t}^3,{}^{\text{'}}=34,D_j=4ft,$ and $D_1=2ft.$ The gross allowable load, $Q_{dll},$ with $FS=3$ is $150,000lb.$ Determine the size of the foundation. Use Eq$.(4\mathrm{.}26).$

Figure $4\mathrm{.}10$ A square foundation

$24$