Abstract: "Soil Improvements Specifications for Building Foundations" recommends formulas for the soilcolumn area replacement ratio, but these formulas are only valid for columns with triangular, square, or rectangular distributions. When the column distribution does belong one of the above distributions, the area replacement ratio cannot be calculated from the code recommended formulas. It is understood that the replacement ratio is ratio of cross section of the column and the area of the tributary. The area replacement ratio can be obtained from the graphical solutions.

Key words: Composite ground, Soil-column area replacement ratio, Equivalent diameter