A foundation base is required to support a 500 mm square column subjected to a vertical load only, for which the values are 4000 kN (services) and 6000 kN (ultimate). The allowable ground bearing value is 250 kN/m². Determine the suitable size of the base and design for flexure if the characteristics strength of concrete (fcu) = 35 MPa and characteristics strength of steel (fy) = 450 MPa, and cover to reinforcement (c) = 50 mm. Check for punching shear and provide a neat diagram to illustrate your design.