BUILDER'S ENGINEER

If the independent footings of two columns are connected by a beam, it is called a strap footing. A strap footing may be used where the distance between the columns is so great that a combined trapezoidal footing becomes quite narrow, with high bending moments. In that case, each column is provided with its independent footings and a beam is used to connect the two footings. The strap beam does not remain in contact with soil, and thus does not transfer

any pressure to the soil. The strap, assumed to be infinitely stiff, serves to transfer the column loads on to the soil with equal and uniform soil pressure under both footings.

Fig. 2.7 shows the strap footing for two columns A and B. Column A is so near to an existing wall that the footing of the wall does not permit the independent footing of column A lo spread out towards the wall, though it has freedom in other directions.