4.8 A concrete slab, 40 ft long, 11 ft wide, and 9 in. thick, is placed on a subgrade having a modu- lus of subgrade reaction of 200 pci. A 9000-lb single-wheel load is applied on the edge of the slab over a circular area with a contact pressure of 100 psi, as shown in Figure P4.8. Compute (a) the curling stress at the edge during the night when the temperature differential is 1.5F per inch of slab, (b) the loading stress due to the 9000-lb wheel load, and (c) the combined stress at the edge beneath the load due to (a) and (b). [Answer: 140.4, 290.3, 149.9 psi] 40 ft h = 9 in. k = 200 pci At = +13.5F %3D 11 ft 100 psi 9000 lb due to combined curling and loading ? FIGURE P4.8