When the independent footings of two columns are connected by a beam, it is called a strap footing.
It is used when the distance between the columns is so great that a combined trapezoidal footing becomes quite narrow, with high bending moments. In this case the column is provided with its independent footings and a beam is used to connect the two footings.
The strap beam doesn’t remain in contact with soil, and thus doesn’t transfer any pressure to the soil. The strap, assumed to be infinitely stiff, serves to transfer the column loads on the soil with equal and uniform soil pressure under both footings.
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