Simplified Footing Design with Interaction Diagrams

Two interaction diagrams for proportioning rigid rectangular or wall footings on soil or rock are presented in this technical note. A new alternative approach to an old problem, based on simplicity and versatility. The content is derived from standard bridge specifications. It covers bearing resistance at the strength limit state of wall foundations on soil and rock, while the loading pattern that has been adopted allows checking against uplift. A unique feature of the proposed design methodology is that the interaction diagrams are derived in a dimensionless form and thus any rectangular shallow foundation on any soil classification can be proportioned with the aid of a single plot.