Problems

$5\mathrm{.}11$ Two $4$ "wide by $12-$feet$-$high brick walls of a garage support a roof slab $20$ feet wide. The roof weighs $100psf$ and carries a snow load of $30psf.$ Check the compressive stress at the base of the wall assuming brick $($for this problem$)$ has a capacity of $125$ psi. Brick weighs $120$ #$/$ ft$.{?}^3$

Hint: Analyze a typical one foot strip of wall.