Knowing the pressure distribution is known, the bending moment and shear force can be calculated, and the thickness of the structural member of the member can be calculated using properties of reinforced concrete.

A strap footing may be used where the distance between the columns is so great that the combined trapezoidal footing becomes quite narrow, with a high bending moment.

In conventional design, the allowable bearing capacity should be taken as the smaller of the following two values: i) the safe bearing capacity based on ultimate capacity, and ii) the allowable bearing pressure on tolerable settlement.

When a footing rests on cohesive soil, the edge stresses may be very large, but the pressure distribution may be considered to be linear.

Both from observations as well as the analytical studies from elasticity, it is known that the pressure distribution beneath footing is not uniform and it depends on the rigidity of footing, the soil type, and the condition of the soil.

When the two columns load are unequal, with the outer column carrying a heavier load, and when there is space limitation beyond the outer column, a trapezoidal footing is provided.

According to Terzaghi, a foundation is shallow if its depth is equal to or less than its width. In the case of deep foundations, the depth is equal to or greater than the width.

The shallow foundations are of the following types: spread footing (or simple footing), strap footing, combined footing, and mat footing or raft footing.

Foundations may be broadly classified under two heads: shallow foundations and deep foundations.

In spread footing, load is transmitted through an isolated column or wall to the subsoil; hence this is most common type of foundation.