Design of spread foundations for transmission structures subject to overturning forces

This paper discusses some of the available methods used for determining the design parameters for spread footing foundations. The discussions are restricted to individual footing foundations. Both concentrically loaded and eccentrically loaded footings are considered. Methods for determining the ultimate bearing capacity and settlement of footings are included as preliminaries for determining the safe allowable pressure to use in design. The theory of subgrade reaction applied to both rigid and flexible foundations is introduced to serve as a motivation for developing the assumptions used on the design of practical footing foundations. The general principles of proportioning and designing footing foundations are illustrated using the ACI 318-71 Building Code as a guideline.