Design a square spread footing for the following conditions: service dead load = 350 kips, service live load = 275 kips. soil density = 130 pcf (including the weight of the floor slab). allowable soil pressure = 4500 psf at 5 ft below the basement floor. assume an 18 in. by 18 in. interior column (f’c = 5000 psi). footing f’c = 3000 psi and fy = 60 ksi. place bottom of footing at 5ft below floor level. estimate floor thickness as 6 in. (hint: estimate thickness of 36 in.)