Consider the footing and loads in Problem, except that the overturning moment now acts at...

Consider the footing and loads in Problem, except that the overturning moment now acts at a 45° angle from the side of the footing (i.e., it acts diagonally across the top of the footing). Determine whether the resultant force acts within the kern. If it does, then compute the bearing pressure at each corner of the footing and show the pressure distribution in a sketch similar to Figure. Determine the size of the equivalent uniformly loaded footing and compute the equivalent bearing pressure.

Problem

A 5 ft square, 2 ft deep spread footing is subjected to a concentric vertical load of 60 k and an overturning moment of 30 ft-k. The overturning moment acts parallel to one of the sides of the footing, and the top of the footing is flush with the ground surface and the groundwater table is at a depth of 20 ft below the ground surface. Determine whether the resultant force acts within the middle third of the footing, compute the minimum and maximum bearing pressures and show the distribution of bearing pressure in a sketch. Determine the size of the equivalent uniformly loaded footing and compute the equivalent bearing pressure.

Figure (a) Pressure distribution beneath spread footing with vertical load that is eccentric in both the B and L directions; and (b) To maintain q ≥ 0 along with the entire base of the footing, the resultant force must be located within this diamond-shaped kern.