An interior column for a manufacturing building will be supported on the site’s natural clay soil, at a shallow depth below the concrete floor slab. The column imposes a loading of 475 kips and will...

An interior column for a manufacturing building will be supported on the site’s natural clay soil, at a shallow depth below the concrete floor slab. The column imposes a loading of 475 kips and will be supported on a square spread footing foundation. The clay soil properties are 117 pcf unit weight and 2,200 psf cohesion value, c (undrained shear strength). The soil rigidity index is 38. The groundwater table is very deep. What size footing should be provided, as determined by the extended bearing capacity equation, using a factor of safety of 3?