Problem $4$

The cross$-$section and plan view of a column footing are shown in the figure on the next page. Calculate the increase in vertical stress due to the footing at point $A$ :

a$.$ Using equation $7\mathrm{.}81$

b$.$ Using the Influence Value chart method

c$.$ Using Newmark's chart $($image attached$)$

${}_z=\frac{q_s}{2}[ta{n}^{-1}(\frac{LB}{z{R}_3})+\frac{LBz}{R_3}(\frac{1}{R_1^2}+\frac{1}{R_2^2})]$ Equation $7\mathrm{.}81$