$(8$ pts$)$ When a concrete slab is subjected to a dual tire loading in the interior as shown

$($center loading$)$ in Figure $4,$ determine the maximum stress $({}_i)$ given the following

conditions:

Figure $4.$ Planview of concrete slab under a set of dual tires

a$.$ The $10,000lb$ load is applied on a set of dual tires.

b$.$ Tires are spaced at $14$ inch on centers.

c$.$ Slab thickness is $10-$inch.

d$.$ Subgrade modulus $($k$)$ is $100$ pci.

e$.$ Tire pressure assumed $=88\mathrm{.}42$

f$.$other conditions can be assumed