A combined footing is subjected to an exterior 16 in. x 16 in. column abutting the property line carrying a total service load Pw = 300,000 lb and an interior column 20 in. x 20 in. carrying a total factored load Pw = 400,000 lb. The live load is 30% of the total load. The center-line distance between the two columns is 22'-0". Design the appropriate reinforced concrete footing on a soil weighing 135 pcf. The bearing capacity of the soil at the level of the footing base is 6000 lb/ft2. The frost line is assumed to be at 3'-6" below grade. Assume a surcharge of 125 psf at grade level. Given:
footing f'c = 3500 psi
column f'c = 5500 psi
fy = 60,000 psi